Light control film and method of making same

Abstract

A light control film has a structured first major surface including structures separated by one or more grooves and having side surfaces. Each groove has one or more landings joining adjacent structures. Each of the side surfaces makes an angle of greater than about 60 degrees with an adjacent landing. At least 80% of the side surfaces and the landings are coated with a first light transmissive layer including inorganic particles at a volume loading of greater than about 5%. At least 70% of the first light transmissive layer on each of the side surfaces and at most 30% of the first light transmissive layer on the landings is coated with a cover layer. The first light transmissive layer coated on the side surfaces has an average surface roughness Ra2, and the first light transmissive layer coated on the landings has an average surface roughness Ra1, where Ra1 > Ra2.

Description

[0001]LIGHT CONTROL FILM AND METHOD OF MAKING SAME Summary In some aspects of the present description, a light control film is provided, the light control film having a structured first major surface opposite a second major surface. The structured first major surface includes a plurality of structures extending in a thickness direction of the light control film separated by one or more grooves. Each structure includes one or more side surfaces. Each groove has one or more substantially planar landings joining the corresponding structures. Each of the one or more side surfaces makes an angle of greater than about 60 degrees with an adjacent landing of the one or more landings. At least 80% of the one or more side surfaces and the one or more landings are coated with a first light transmissive layer having a first average thickness of greater than about 0.005 microns and including a plurality of first inorganic particles at a volume loading of greater than about 5%. At least 70% of the first light transmissive layer on each of the one or more side surfaces and at most 30% of the first light transmissive layer on the one or more landings is coated with a cover layer. The first light transmissive layer coated on the one or more side surfaces has an arithmetic average surface roughness Ra2. The first light transmissive layer coated on the one or more landings has an arithmetic average surface roughness Ra1, such that Ra1 > Ra2. In some aspects of the present description, a method of making a light control film is provided, the method including providing a substantially light transmissive film having a structured first major surface and an opposing second major surface, the structured first major surface having a plurality of structures separated by one or more grooves extending in a thickness direction of the light control film, each structure having one or more side surfaces, each groove having one or more substantially planar landings joining the corresponding structures, each of the one or more side surfaces making an angle with an adjacent landing of the one or more landings of greater than about 60 degrees; coating the structured first major surface with a light transmissive layer, the light transmissive layer covering at least 80% of each of the plurality of structures and the one or more grooves and including a plurality of first inorganic particles at a volume loading of greater than about 5%; coating the light transmissive layer with a cover layer so that at least 80% of the light transmissive layer is covered by the cover layer; and etching the cover layer using a directional first etching process to remove more than about 80% of the cover layer from the one or more landings but less than about 40% of the cover layer from each of the one or more side surfaces, resulting in the light transmissive layer coated on the one or more landings and the one or more side surfaces having respective arithmetic average surface roughnesses Ra1 and Ra2, wherein Ra1 > Ra2. In some aspects of the present description, a light control film is provided, the light control film including a light transmissive body having a plurality of structures extending in a thickness direction of the light control film separated by one or more grooves, each structure having one or more side surfaces, each groove having one or more substantially planar landings joining the corresponding structures; a first light transmissive layer having a first average thickness of greater than about 0.005 microns and coated on at least 80% of the plurality of structures and the one or more landings, the light transmissive layer including a plurality of first inorganic particles comprising a first inorganic material; a light absorbing layer having an average thickness of greater than about 0.05 microns and coated on at least 70% of the light transmissive layer on the one or more side surfaces and on at most 30% of the light transmissive layer on each of the one or more landings; and a planarizing overcoat covering the light absorbing layer and substantially planarizing the structured first major surface. For each of at least some of one or more side surfaces and the one or more landings, a second light transmissive layer is disposed between the planarizing overcoat and the light absorbing layer, the second light transmissive layer including the first inorganic material and having a second average thickness that is less than about 20 nm. Brief Description of the Drawings FIGS.1A-1C provide side, cross-sectional views of a light control film, in accordance with an embodiment of the present description; FIGS.2A-2B provide additional details for a light control film, in accordance with an embodiment of the present description; FIGS.3A-3B present contrasting top and side profile views of a light control film, respectively, in accordance with an embodiment of the present description; FIG.4 provide details on the structure of a light control film, including angles and widths of various features, in accordance with an embodiment of the present description; FIGS.5A-5B show embodiments of light transmissive and cover layers of a light control film, in accordance with an embodiment of the present description; FIGS.6A-6D illustrate display systems including a light control film, in accordance with an embodiment of the present description; FIG.7 illustrates a method of making a light control film, in accordance with an embodiment of the present description; FIG.8 includes a microscope image of a light control film, in accordance with an embodiment of the present description; FIGS.9A-9D illustrate various versions of a light control film, in accordance with alternate embodiments of the present description; and FIGS.10-15 are provided as illustrations for the Examples section of this specification, and are referenced and described within the Examples section. Detailed Description In the following description, reference is made to the accompanying drawings that form a part hereof and in which various embodiments are shown by way of illustration. The drawings are not necessarily to scale. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present description. The following detailed description, therefore, is not to be taken in a limiting sense. Etch stops (also known as etch masks or hard masks) are ubiquitous in microelectronics manufacturing where they allow for termination of an etching process to a controlled depth. Etch stops can function in wet and / or dry etching processes. The etch stops for dry etching (e.g., reactive ion etching, or RIE) are typically inorganic coatings (e.g., oxides or nitrides or metals) and would typically comprise a continuous inorganic layer, as opposed to a layer of discrete inorganic nanoparticles. According to some aspects of the present description, the layer-by-layer (LbL) coating method (a liquid phase coating method) is used to deposit dry etch stops comprising inorganic oxide particles and oppositely charged polymers, or two oppositely charged inorganic oxide particles. LbL deposition involves the sequential assembly of at least two different materials with binding groups, which are complementary to each other (e.g., oppositely charged functional groups or H-bond donor and acceptors groups, etc.). This coating method can provide very high loadings of inorganic particles (of various shapes and sizes), for example loadings of greater than or equal to 25 wt%, greater than or equal to 50 wt%, greater than or equal to 75 wt%, greater than or equal to 90 wt%, or greater than or equal to 99 wt%, as can be measured by thermogravimetric analysis (TGA), for example. Likewise, very high-volume loadings of inorganic particles can be achieved, for example loadings of greater than or equal to 10 vol%, greater than or equal to 25 vol%, greater than or equal to 50 vol%, greater than or equal to 75 vol%, as can be measured by scanning electron microscopy (SEM) and / or transmission electron microscopy (TEM), for example. The coatings may also be porous, especially when spherical nanoparticles are used. It is unexpected that a porous and / or organic-containing composite coating could function as an effective dry etch stop. Relevant inorganic materials for the etch stops of the present description may include metal oxide nanoparticles such as silicon dioxide (silica), aluminum oxide (alumina), zirconium oxide (zirconia), titanium dioxide (titania), and the like. Other relevant metal oxides include clay platelets, such as aluminosilicates (e.g., montmorillonite, vermiculite, and the like) or lithium magnesium silicates (e.g., LAPONITE®). Still more relevant inorganic materials include MXenes, as well as sulfide or nitride particles. Metal nanoparticles and platelets are also in scope. Some inorganic materials possess binding groups (e.g., charged functional groups) on their unmodified surfaces, while others may require surface modification. Relevant organic binder materials for the etch stops of this invention include charged polymers (i.e., polyelectrolytes). These polymers can be water soluble or can be water insoluble, but stable in water as emulsions, dispersions, or suspensions. The polymers must possess binding groups (e.g., charged functional groups), either as part of the polymer backbone or side chains, or through surface modification by a charged surfactant. Typical negatively charged groups may include, for example, carboxylate, sulfonate, phosphate, or phosphonate groups, while typical positively charged groups may include, for example, primary, secondary, or tertiary amines, and quaternary ammonium groups, or phosphonium or sulfonium groups, for example. Compared to classic dry etch stops deposited via vacuum deposition, LbL-deposited etch stops have the benefit of not requiring a vacuum chamber. Vacuum chambers require time for pump down and also can complicate web handling. In addition, it has been shown that LbL-deposited etch stops such as those described herein can surprisingly provide superior adhesion to certain polymer resins compared to standard etch stops (e.g., those deposited by plasma-enhanced chemical vapor deposition, or PE-CVD). According to some aspects of the present description, a light control film includes a structured first major surface opposite a second major surface. In some embodiments, the structured first major surface may include a plurality of structures extending in a thickness direction (e.g., a z-direction) of the light control film separated by one or more grooves (e.g., channels or valleys extending between adjacent structures). In some embodiments, each structure of the plurality of structures may include one or more side surfaces. In some embodiments, each groove may have one or more substantially planar landings (i.e., planar surfaces extending between) joining the corresponding structures. In some embodiments, each of the one or more side surfaces may make an angle of greater than about 60 degrees, or greater than 65 degrees, or greater than 70 degrees, or greater than about 75 degrees, or greater than about 80 degrees, or greater than about 85 degrees, with an adjacent landing of the one or more landings. It should be noted that reference to degrees here refer to the magnitude of the angle, no matter the relative direction of the angle relative to the substantially planar landing. That is, as an example, an angle of 85 degrees would be considered equivalent to an angle of -85 degrees if only magnitude is considered. For example, one side surface may be at an angle of 85 degrees to the landing and leaning to the right, which an adjacent side surface may be at an angle of 85 degrees but leaning to the left. In some embodiments, at least 80%, or at least 85%, or at least 90%, or at least 95% of the one or more side surfaces and the one or more landings may be coated with a first light transmissive layer having a first average thickness of greater than about 0.005 microns. In some embodiments, the first light transmissive layer may include a plurality of first inorganic particles at a volume loading of greater than about 5%. In some embodiments, the volume loading of the first inorganic particles may be at a volume loading of from about 5% to about 95%, or from about 5% to about 80%, or from about 5% to about 70%, or from about 7% to about 70%, or from about 10% to about 70%. In some embodiments, the inorganic particles in the light transmissive layer may be spherical, aspherical, oblong, or platelets, or any other appropriate shape. In some embodiments, the particles may be non-aggregated, individual particles, loose aggregates of individual particles, or permanent aggregates of primary particles. In some embodiments, the particles may be amorphous, crystalline, or semi-crystalline. In some embodiments, the first inorganic particles may be sputtered particles which enter a vapor phase as atoms or small atom clusters which may then be redeposited as an integral material layer. In the case of spherical inorganic particles, typical primary / individual particle diameters may range from about 1 nm to about 190 nm, or from about 1 nm to about 75 nm, or from about 1 nm to about 50 nm. In the case of non-spherical particles, the longest dimension would typically range from about 4 nm to about 3000 nm, or from about 4 nm to about 1000 nm, or from about 4 nm to about 500 nm, or from about 4 nm to about 250 nm, or from about 4 nm to about 75 nm. In the case of platelets, they may be fully or partially exfoliated with aspect ratios less than about 3000:1, or less than about 1000:1, or less than about 500:1, or less than about 250:1, or less than about 50:1. In some embodiments, platelets may have an aspect ratio greater than about 5:1. The particle size (e.g., diameter or longest dimension) of the inorganic particles in the light transmissive layer can be measured by scanning electron microscopy (SEM) or transmission electron microscopy (TEM), for example. In some embodiments, the particle size distribution of the inorganic particles in the light transmissive layer may be, for example, monodisperse, polydisperse, multimodal (e.g., bimodal, or trimodal). Various embodiments may include mixtures of the different types of particles described above. In some embodiments, the light transmissive layer may have an average thickness in a range of between about 0.005 microns and about 0.500 microns, or between about 0.01 microns and about 0.400 microns, or between about 0.03 microns and about 0.300 microns. In some embodiments, at least 70%, or at least about 75%, or at least about 80%, or at least about 85%, or at least about 90%, or at least about 95% of the first light transmissive layer on each of the one or more side surfaces, and at most 30%, or at most about 25%, or at most about 20%, or at most about 15%, or at most about 10%, or at most about 5% of the first light transmissive layer on the one or more landings, may be coated with a cover layer. In some such embodiments, the cover layer may have an average thickness of greater than about 0.05 microns. In some embodiments, the light absorbing cover layer may have an average thickness of greater than about 0.05 microns, or greater than about 0.1 microns, or greater than about 0.15 microns, or greater than about 0.2 microns, or greater than about 0.25 microns, or greater than about 0.3 microns, or greater than about 0.35 microns, or greater than about 0.4 microns, or greater than about 0.45 microns, or greater than about 0.5 microns, or greater than about 0.55 microns, or greater than about 0.6 microns, or greater than about 0.65 microns, or greater than about 0.7 microns, or greater than about 0.75 microns, or greater than about 1.0 microns, or greater than about 1.25 microns, or greater than about 1.5 microns, or greater than about 2 microns, or greater than about 2.5 microns, or greater than about 3 microns. In some embodiments, the cover layer may have an average thickness of less than about 2000 nm, or less than about 1500 nm, or less than about 1000 nm, or less than about 500 nm, or less than about 400 nm, or less than about 300 nm, or less than about 200 nm, or less than about 100 nm, or less than about 50 nm. In some embodiments, the cover layer may be a multilayer coating with core clad structure (i.e., may include a core layer disposed between a first cladding layer and a second cladding layer, as described in US Patent No.11,550,183, which is hereby included by reference). In some embodiments, the first light transmissive layer may be coated on the one or more side surfaces and may have an arithmetic average surface roughness Ra2. In some embodiments, the first light transmissive layer coated on the one or more landings may have an arithmetic average surface roughness Ra1. In some embodiments, Ra1 may be greater than Ra2 (i.e., the surface of the first light transmissive layer coated on the one or more landings may be rougher than the surface of the first light transmissive layer coated on the one or more side surfaces). For example, the surface roughness of the light transmissive layer on the landings may be affected more readily by a directional etching process than the surface roughness of the light transmissive layer on the side surfaces (e.g., the “direction” of the directional etching process may be more orthogonal to the landings than to the side surfaces). In some embodiments, Ra2 may be greater than zero. In some embodiments, the one or more side surfaces (i.e., the side surfaces themselves, not the light transmissive layer on top of them) may have an arithmetic surface roughness within about 10%, or within about 5%, or within about 1% of Ra2. In some embodiments, the one or more landings may have an arithmetic surface roughness less than about Ra1 / 10, or less than about Ra1 / 25, or less than about Ra1 / 50. Stated another way, the light transmissive layer on top of the landings may have a roughness Ra1, while the landings themselves are smoother (e.g., about Ra1 / 10 or less). In some embodiments, the one or more side surfaces may include a first side surface and a second side surface connected by a substantially planar top surface that is substantially parallel to the one or more landings. In some such embodiments, at most 30% of the first light transmissive layer on the planar top surface may also be coated with a cover layer, and the planar top surface may have an arithmetic average surface roughness substantially the same as the first light transmissive layer coated on the one or more landings. In some embodiments, the one or more side surfaces may include a first side surface and a second side surface meeting at a peak (e.g., a triangular prism). In some embodiments, the plurality of structures may include linear structures extending substantially across a width direction of the light control film (e.g., an y-direction) and arranged along an orthogonal length direction (e.g., a x-direction) of the light control film. In some such embodiments, each linear structure may be separated from each adjacent linear structure by a groove. In some embodiments, the plurality of structures comprises a plurality of posts arranged along a width direction and an orthogonal length direction of the light control film. In some embodiments, at least a portion of the posts in the plurality of posts may be substantially surrounded by the one or more landings. In some such embodiments, the one or more side surfaces may include a single side surface (e.g., a continuous, external side surface of a cylindrical post) or may include multiple side surfaces (e.g., such as the sides of a triangular pyramid post or a rectangular prism post). In some embodiments, the light control film may further include a second light transmissive layer disposed on at least a portion of the cover layer. The second light transmissive layer may include the first inorganic material. In some embodiments, the source of this second light transmissive layer may be redeposition during a selective etch step composed of nonvolatile etch byproducts from the first light transmissive layer. In some embodiments, the second light transmissive layer may have a second average thickness less than the first average thickness of the first light transmissive layer. In some embodiments, the second average thickness may be less than about 20 nm, or less than about 10 nm, or less than about 5 nm. In some such embodiments, the second light transmissive layer may be discontinuous. In some embodiments, at least one of the first light transmissive layer and the cover layer may be porous (e.g., having a plurality of pores). In some such embodiments, a volume fraction of the pores is greater than 0.2, or greater than 0.3, or greater than 0.4, or greater than 0.5, or greater than 0.6, or greater than 0.7. In some embodiments, at least one of the light transmissive and cover layers may be physically discontinuous including a plurality of spaced apart islands. In some embodiments, the cover layer may be light absorbing. The cover layer may absorb light at one more wavelengths in the ultraviolet light range (i.e., 100-400 nm) and / or the visible light range (i.e., 400-700 nm) and / or the infrared light range (i.e., 700 nm – 1 mm). In some such embodiments, the light absorbing cover layer may include a plurality of light absorbing particles. In some such embodiments, the light absorbing particles may include one or more of a dye, a pigment, and a carbon black. In some embodiments, the light absorbing cover layer may have an optical density, at one or more wavelengths from 100 nm to 1 mm of greater than about 0.1, or greater than about 0.2, or greater than about 0.4, or greater than about 0.6, or greater than about 0.8, or greater than about 1, or greater than about 1.1, or greater than about 1.2, or greater than about 1.3, or greater than about 1.4, or greater than about 1.5, or greater than about 2, or greater than about 2.5, or greater than about 3, or greater than about 3.5, or greater than about 4, or greater than about 4.5, or greater than about 5, or greater than about 5.5, or greater than about 6. In some embodiments, the optical density is less than about 3.0, or less than about 2.5, or less than about 2.0. In some embodiments the optical density is between 0.5 and 2.5, or between 1.0 and 2.0 or between 1.2 and 1.8. As used herein, optical density shall be defined as -log10(T), where T is the optical transmission of the film, and T is defined as It / Io, where Iois the intensity of incident light and Itis the intensity of the transmitted light (light passing through the medium). For example, if transmission, T, is 1%, the optical density is calculated as -log10(0.01) which is equal to an optical density of 2.0. In some embodiments, a layer-by-layer (LbL) coating method, the same method that can be used to deposit the etch stop, is used to deposit the cover layer. In this case, the cover layer would comprise at least one material with a first binding group and a second material with a second binding group, the first binding group and second binding group having complementary interactions. Typically, the first material is a polymer binder (e.g., a polyelectrolyte). The polymer binder may be the same polymer binder present in the etch stop or may be a different polymer. In the case when the cover layer is light-absorbing, the second material would typically be a light-absorbing pigment, dye, or a carbon black comprising binding groups complementary to those in the first material. Suitable pigments include, for example, ionically-modified pigment nanoparticles commercially available as inkjet pigment colorants under the trade designation CAB-O-JET from Cabot Corporation (Boston, MA) such as black, cyan, magenta, and / or yellow pigments, or inkjet pigments from the BONJET Black Series from Orient Corporation of America (Cranford, NJ). In general, pigments or other wavelength-selective light absorbing particles may be functionalized either by being covalently surface modified or non-covalently surface modified, for example, with an ionic surfactant. Some of major classes of dyes / pigments include phthalocyanines, cyanine, transition metal dithioline, squarylium, croconium, quinones, anthraquinones, iminium, pyrylium, thiapyrylium, azulenium, azo, perylene and indoanilines. Many of these dyes and pigments can exhibit visible and / or infrared light absorption as well. Further, many different types of visible dyes and colorants may be used such as acid dyes, azoic coloring matters, coupling components, diazo components. Basic dyes include developers, direct dyes, disperse dyes, fluorescent brighteners, food dyes, ingrain dyes, leather dyes, mordant dyes, natural dyes and pigments, oxidation bases, pigments, reactive dyes, reducing agents, solvent dyes, sulfur dyes, condense sulfur dyes, vat dyes. Some of the organic pigments may belong to one or more of monoazo, azo condensation, insoluble metal salts of acid dyes and disazo, naphthols, arylides, diarylides, pyrazolone, acetoarylides, naphthanilides, phthalocyanines, anthraquinone, perylene, flavanthrone, triphendioxazine, metal complexes, quinacridone, polypyrrole etc. Suitable dyes for the cover layer could include, for example, acid dyes or basic dyes; some specific examples include, without limitation, Acid Orange 12, Acid Blue 25, Eriochrome Black T, Lissamine Green B, Acid Fuchsin, Alizarin Blue Black B, Acid Blue 80, Acid Blue 9, Brilliant Blue G, Water Soluble Nigrosin, Methylene Blue, Crystal Violet, Safranin, Basic Fuchsin, and combinations thereof. Note that dyes with just one or a few charged functional groups, for example, may not be suitable as a material for layer-by-layer deposition directly; however, such dyes can be ion exchanged into layer-by-layer coatings as disclosed in WO2023 / 047204 (Schmidt et al.). The light absorbing material in the light-absorbing cover layer may comprise individual dye molecules, aggregates of dye molecules, and / or pigment particles, for example. The pigment or carbon black particles in the light-absorbing cover layer may be spherical, aspherical, oblong, or platelets, for example. The particles may be non-aggregated, individual particles, or they may be loose aggregates of individual particles, or they may be permanent aggregates of primary particles. The particles may be amorphous, crystalline, or semi-crystalline. In the case of spherical particles, typical primary / individual particle diameters range from 1 nm to 190 nm, more preferably from 5 nm to 100 nm. In the case of non-spherical particles, the longest dimension would typically range from 4 nm to 3000 nm, or from 4 nm to 1000 nm, or from 4 nm to 500 nm, or from 4 nm to 250 nm, or from 4 nm to 75 nm. In the case of platelets, they may be fully or partially exfoliated with aspect ratios less than 3000:1, less than 1000:1, less than 500:1, less than 250:1, or less than 50:1. Platelets would typically have an aspect ratio greater than 5:1. The particle size (e.g., diameter or longest dimension) of the particles in the cover layer can be measured by scanning electron microscopy (SEM) or transmission electron microscopy (TEM), for example. The particle size distribution of the particles in the cover layer may be, for example, monodisperse, polydisperse, bimodal, or multimodal (e.g., bimodal or trimodal). Various embodiments may include mixtures of the different types of particles described above. In some embodiments, the light control film may further include a planarizing overcoat covering, and substantially planarizing, the structured first major surface. In some embodiments, a refractive index of the planarizing overcoat may be substantially the same as a refractive index of the plurality of structures. In some embodiments, the refractive index of the planarizing overcoat may be different from the refractive index of the plurality of structures by a value of less than 0.05, or less than 0.04, or less than 0.03. In some such embodiments, a refractive index of the planarizing overcoat may be different from a refractive index of the plurality of structures by greater than about 0.07, or greater than about 0.09, or greater than about 0.1, or greater than about 0.13, or greater than about 0.15, or greater than about 0.2, or greater than about 0.25. In some embodiments, the first inorganic particles of the first light transmissive layer may include one or more of silicon dioxide, titanium dioxide, zirconium dioxide, aluminum oxide, and clay platelets. In embodiments where the first organic particles are clay platelets, the clay platelets may include silicates. In some such embodiments, the silicates may include one or more of aluminum silicates and magnesium silicates. In some embodiments, the first inorganic particles of the first light transmissive layer may be dispersed in a polymeric binder at the weight loading of greater than about 15%. In some such embodiments, one of the polymeric binder and the plurality of first inorganic particles may include a plurality of positively charged ionic groups (i.e., ionic, or ionizable group), and the other one of the polymeric binder and the plurality of first inorganic particles may include a plurality of negatively charged ionic groups. In some such embodiments, the polymeric binder may include one or more of poly(ethylenimine) (PEI), poly(allylamine hydrochloride), polyvinylamine, chitosan, polyaniline, polyamidoamine, poly(vinylbenzyltrimethylamine), polydiallyldimethylammonium chloride (PDAC), poly(dimethylaminoethyl methacrylate), poly(methacryloylamino)propyl-trimethylammonium chloride, poly(vinyl sulfate), poly(vinyl sulfonate), poly(acrylic acid) (PAA), poly(methacrylic acid), poly(styrene sulfonate), dextran sulfate, heparin, hyaluronic acid, carrageenan, carboxymethylcellulose, alginate, sulfonated tetrafluoroethylene based fluoropolymers, poly(vinylphosphoric acid), poly(vinylphosphonic acid), polyurethane, and acrylic. In some embodiments of the light control film, any binder in the first light transmission layer may be at a weight loading of not greater than about 20%, or not greater than about 15%, or not greater than about 10%, or not greater than about 5%, or not greater than about 4%, or not greater than about 3%, or not greater than about 2%, or not greater than about 1%. In some embodiments, the first light transmission layer does not include any binder. In some embodiments, the first light transmissive layer may further include a plurality of second inorganic particles. In some such embodiments, the second inorganic particles may include one or more of silicon dioxide, titanium dioxide, zirconium dioxide, aluminum oxide, and clay platelets. In some such embodiments, the clay platelets may include silicates. In some such embodiments, the silicates may include one or more of aluminum silicates and magnesium silicates. In some such embodiments, one of the plurality of first inorganic particles and the plurality of second inorganic particles may include a plurality of positively charged ionic groups, and the other one of the plurality of first inorganic particles and the plurality of second inorganic particles may include a plurality of negatively charged ionic groups. In some embodiments, a display system may include any of the light control films described herein, or similar embodiments, and a display configured to form an image to a viewer. In some such embodiments, the light control film may be disposed between the viewer and the display. In some such embodiments, the display may include an LCD or OLED display. In some embodiments, a display system may include any of the light control films described herein, or similar embodiments, an LCD display panel configured to form an image to a viewer, and a backlight. In some embodiments, the light control film may be disposed between the light LCD display panel and the backlight. In some such embodiments, the display system may further include a multilayer optical film which is optically coupled to the light control film. In some embodiments, the multilayer optical film may be disposed between the light control film and the backlight. In some embodiments, a display system may include any of the light control films described herein, or similar embodiments and an OLED display configured to display an image to a viewer. In some embodiments, the OLED display may include a circular polarizer. In some embodiments, the light control film may be disposed between the OLED display and the viewer. In some such embodiments, the display system may further include a plurality of optically functional layers optically coupled to each other. In some such embodiments, substantially no airgap exists between any adjacent optically functional layers. According to some aspects of the present description, a method of making a light control film includes providing a substantially light transmissive film having a structured first major surface and an opposing second major surface, the structured first major surface including a plurality of structures separated by one or more grooves extending in a thickness direction of the light control film, each structure including one or more side surfaces, and each groove having one or more substantially planar landings joining the corresponding structures, each of the one or more side surfaces making an angle with an adjacent landing of the one or more landings of greater than about 60 degrees, or greater than about 65 degrees, or greater than about 70 degrees, or greater than about 75 degrees, or greater than about 80 degrees, or greater than about 85 degrees; coating the structured first major surface with a light transmissive layer, the light transmissive layer covering at least 80%, or at least 85% or at least 90%, or at least 95% of each of the plurality of structures and the one or more grooves and including a plurality of first inorganic particles at a volume loading of greater than about 5%; coating the light transmissive layer with a cover layer so that at least 80% of the light transmissive layer is covered by the cover layer; and etching the cover layer using a directional first etching process (e.g., reactive ion etching) to remove more than about 80%, or more than about 85%, or more than about 90%, or more than about 95%, or more than about 99% of the cover layer from the one or more landings but less than about 40%, or less than about 30%, or less than about 25%, or less than about 20%, or less than about 15%, or less than about 10%, or less than about 5% of the cover layer from each of the one or more side surfaces. In some embodiments, the method of making a light control film may result in the light transmissive layer coated on the one or more landings and the one or more side surfaces having respective arithmetic average surface roughnesses Ra1 and Ra2, such that Ra1 > Ra2. In some embodiments, Ra2 may be greater than zero. In some embodiments, the method of making a light control film may further include covering and substantially planarizing the structured first major surface with a planarizing overcoat. According to some aspects of the present description, a light control film includes a light transmissive body having a plurality of structures extending in a thickness direction (e.g., a z- direction) of the light control film separated by one or more grooves, a first light transmissive layer, a light absorbing layer, and a planarizing overcoat. In some embodiments, each structure may have one or more side surfaces. In some embodiments, each groove may have one or more substantially planar landings joining the corresponding structures. In some embodiments, the first light transmissive layer may have a first average thickness of greater than about 0.005 microns and may be coated on at least 80% of the plurality of structures and the one or more landings. In some embodiments, the light transmissive layer may include a plurality of first inorganic particles including a first inorganic material. In some embodiments, the light absorbing layer may have an average thickness of greater than about 0.05 microns and may be coated on at least 70%, or at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95% of the light transmissive layer on the one or more side surfaces and on at most 30%, or at most 25%, or at most 20%, or at most 15%, or at most 10%, or at most 5% of the light transmissive layer on each of the one or more landings. In some embodiments, the planarizing overcoat may cover the light absorbing layer and may substantially planarize the structured first major surface. In some embodiments, for each of at least some of one or more side surfaces and the one or more landings, a second light transmissive layer is disposed between the planarizing overcoat and the light absorbing layer. In some such embodiments, the second light transmissive layer may include the first inorganic material and may have a second average thickness that is less than about 20 nm, or less than about 10 nm, or less than about 5 nm.. In some embodiments, the second light transmissive layer may be discontinuous. In some embodiments, a refractive index of the planarizing overcoat may be substantially the same as the plurality of structures. In some embodiments, the refractive index of the planarizing overcoat may be different from the refractive index of the plurality of structures by a value of less than 0.05, or less than 0.04, or less than 0.03. In some embodiments, a refractive index of the planarizing overcoat may be different from a refractive index of a material of the first major surface by greater than about 0.07. In some embodiments, the light control film may be bonded to an adhesive. In some such embodiments, the adhesive may be a pressure sensitive adhesive. In some such embodiments, the adhesive may be at least one of an acrylic adhesive, a synthetic rubber adhesive, a natural rubber adhesive, and a silicone adhesive. In some such embodiments, the adhesive may have a haze value of at least 10%. In other embodiments, the adhesive may be an optically clear adhesive (OCA) with less than 5% haze. Turning now to the figures, FIGS.1A-1C provide side, cross-sectional views of an embodiment of a light control film, according to the present description. Looking first at FIG.1A, but with FIGS.1B and 1C in mind, in some embodiments, light control film 300 may include a light transmissive body 10 having a structured first major surface 11 opposite a second major surface 12. In some embodiments, the structured first major surface 11 may include a plurality of structures 10a extending in a thickness direction of the light control film (e.g., the z-direction of FIG.1A) separated by one or more grooves 28. In some embodiments, each structure 10a may include one or more side surfaces 30a, 30b (collectively side surfaces 30). In some embodiments, each groove 28 may have one or more substantially planar landings 25 joining the corresponding adjacent structures 10a. In some embodiments, each of the one or more side surfaces 30a, 30b may make an angle θ1, θ2 with an adjacent landing 25 or with the second major surface 12. In some embodiments, the angle θ1, θ2 may be greater than about 60 degrees, or greater than about 65 degrees, or greater than about 70 degrees, or greater than about 75 degrees, or greater than about 80 degrees, or greater than about 85 degrees. In some embodiments, embodiments angles θ1 and θ2 may be substantially identical in magnitude but may be opposing in sign (i.e., each angle may be inclined toward the other angle, as shown in FIG. 1A). In some embodiments, angles θ1 and θ2 may be about 90 degrees (i.e., substantially orthogonal to landing 25 or to second major surface 12). In some embodiments, at least 80% of the one or more side surfaces 30a, 30b and the one or more landings 25 may be coated with a first light transmissive layer 40 having a first average thickness, h, of greater than about 0.005 microns. In some embodiments, first light transmissive layer 40 may have an average thickness in a range of between 0.005 microns and 0.500 microns, or from 0.01 microns to 0.400 microns, or from about 0.03 microns to about 0.300 microns. In some embodiments, at least 70% of first light transmissive layer 40 on each of the one or more side surfaces 30a, 30b and at most 30% of the first light transmissive layer 40 on the one or more landings 25 may be coated with a cover layer 50. Stated another way, cover layer 50 may cover more of side surfaces 30a, 30b than it covers the one or more landings 25. In some embodiments, the first light transmissive layer 40 coated on the one or more side surfaces 30a, 30b may have an arithmetic average surface roughness Ra2, and the first light transmissive layer 40 coated on the one or more landings 25 may have an arithmetic average surface roughness Ra1. In some embodiments, Ra1 may be greater than Ra2. Stated another way, the average surface roughness Ra2 of side surfaces 30 (e.g., 30a, 30b) may be less than (smoother than) the average surface roughness Ra1 of landings 25. In some embodiments, Ra2 may be greater than zero. In some embodiments, the one or more side surfaces 30, 30a, 30b (i.e., the surfaces beneath or without the cover of first light transmissive layer 40) may have an arithmetic surface roughness within about 10% of Ra2 (i.e., they may have an average surface roughness substantially similar to Ra2). In some embodiments, the one or more landings 25 may have an arithmetic surface roughness less than about Ra1 / 10 (i.e., the first light transmissive layer 40 on top of the landings has roughness Ra1, while the landings 25 themselves, beneath the first light transmissive layer 40, are considerably smoother, less than about a tenth of Ra1). In some embodiments, one or more side surfaces 30a, 30b may include a first side surface 30a and a second side surface 30b connected by a substantially planar top surface 20. In some embodiments, the substantially planar top surface 20 may be substantially parallel to the one or more landings 25. In some such embodiments, at most 30% of first light transmissive layer 40 on the planar top surface 20 may be coated with cover layer 50. In some embodiments, planar top surface 20 may have an arithmetic average surface roughness Ra2 substantially the same as the first light transmissive layer 40 coated on the one or more landings 25 (i.e., the average surface roughness of first light transmissive layer 40 on planar top surface 20 may be substantially the same as the average surface roughness of first light transmissive layer 40 on the one or more landings 25). Turning to FIGS.1B and 1C, in some embodiments, first light transmissive layer 40 may include a plurality of first inorganic particles 41 at a volume loading of greater than about 5%. In some embodiments, the first inorganic particles 41 may include one or more of silicon dioxide, titanium dioxide, zirconium dioxide, aluminum oxide, and clay platelets (e.g., the clay platelets may include silicates, including one or more of aluminum silicates and magnesium silicates). In some embodiments, light transmissive layer 40 may include a plurality of first inorganic particles 41 (FIG.1B) at a weight loading of greater than about 15%, or greater than about 20%, or greater than about 25%, or greater than about 30%, or greater than about 40%, or greater than about 50%, or greater than about 60%, or greater than about 70%, or greater than about 80%, or greater than about 90%, or greater than about 95%, or greater than about 96%, or greater than about 97%, or greater than about 98%, or greater than about 99%. In some embodiments, the first inorganic particles 41 of the light transmissive layer 40 may be dispersed in a polymeric binder 42 at the weight loading of greater than about 15%. In some embodiments the first inorganic particles 41 are included at a weight loading of from about 15% to 99%, or from 20% to 80%, or from 25% to 70%. In some embodiments, the light transmissive layer may have a plurality of first inorganic particles 41 at a volume loading of from about 5% to 95%, or from about 5% to 80%, or from 5% to 70%, or from 10% to 70%. In some embodiments, the first inorganic particles 41 may include one or more of silicon dioxide, titanium dioxide, zirconium dioxide, aluminum oxide, and clay platelets (e.g., the clay platelets may include silicates, including one or more of aluminum silicates and magnesium silicates). In some embodiments, one of the polymeric binder 42 and the plurality of first inorganic particles 41 may include a plurality of positively charged ionic groups, and the other one of the polymeric binder 42 and the plurality of first inorganic particles 41 may include a plurality of negatively charged ionic groups. Ionic groups can be inherently present on the surface of the inorganic particles; below the isoelectric point of the inorganic particle, the surface would possess a plurality of positively charged functional groups (i.e., net positive charge), while, above the isoelectric point, the surface would possess a plurality of negatively charged functional groups (i.e., net negative charge). Alternatively, inorganic particles can be surface-functionalized or surface-modified to impart charged functional groups. Surface functionalization / modification can be done with inorganic and / or organic materials. An example material with inorganic surface modification is colloidal silica with an alumina surface, such as Nalco 1056 (available from Nalco Water, Naperville, IL). As another example, silicon dioxide particles can be surface functionalized with an amino silane to impart positively charged amine groups to the surface. In some embodiments, the polymeric binder 42 may include one or more of poly(ethylenimine) (PEI), poly(allylamine hydrochloride), polyvinylamine, chitosan, polyaniline, polyamidoamine, poly(vinylbenzyltriamethylamine), polydiallyldimethylammonium chloride (PDAC), poly(dimethylaminoethyl methacrylate), poly(methacryloylamino)propyl- trimethylammonium chloride, poly(vinyl sulfate), poly(vinyl sulfonate), poly(acrylic acid) (PAA), poly(methacrylic acid), poly(styrene sulfonate), dextran sulfate, heparin, hyaluronic acid, carrageenan, carboxymethylcellulose, alginate, sulfonated tetrafluoroethylene based fluoropolymers, poly(vinylphosphoric acid), poly(vinylphosphonic acid), polyurethane, and acrylic. In some embodiments, first light transmission layer 40 may contain a binder at a low weight loading. For example, any binder in first light transmission layer 40 may be at a weight loading of not greater than about 20%, or not greater than about 15%, or not greater than about 10%, or not greater than about 5%, not greater than about or 4%, or not greater than about 3%, or not greater than about 2%, or not greater than about 1%. In some embodiments, first light transmission layer 40 may not include any binder. In some embodiments, first light transmissive layer 40 may further include a plurality of second inorganic particles 43 (FIG.1C). In some such embodiments, the second inorganic particles 43 may include one or more of silicon dioxide, titanium dioxide, zirconium dioxide, aluminum oxide, and clay platelets (e.g., the clay platelets may include silicates, including one or more of aluminum silicates and magnesium silicates). In some embodiments, one of the plurality of first inorganic particles 41 and the plurality of second inorganic particles 43 may include a plurality of positively charged ionic groups, and the other one of the plurality of first inorganic particles 41 and the plurality of second inorganic particles 43 may include a plurality of negatively charged ionic groups. In some embodiments, light control film 300 may further include a planarizing overcoat 90 covering, and substantially planarizing, structured first major surface 11. In some embodiments, a refractive index of the planarizing overcoat may be substantially the same as a refractive index of the plurality of structures. In some embodiments, the refractive index of the planarizing overcoat may be different from the refractive index of the plurality of structures by a value of less than 0.05, or less than 0.04, or less than 0.03. In some embodiments, a refractive index of the planarizing overcoat may be different from a refractive index of the plurality of structures by greater than about 0.07. FIGS.2A-2B provide additional details for a light control film, such as the light control film 300 of FIG.1A. The following discussion addresses FIGS.1A-1C and 2A-2B as a whole and the figures should be reviewed in conjunction. Looking first at FIG.2A, light control film 300 includes a light transmissive body 10 having a structured first major surface 11 opposite a second major surface 12. In some embodiments, the structured first major surface 11 may include a plurality of structures 10a extending in a thickness direction of the light control film separated by one or more grooves 28. In some embodiments, each structure 10a may include one or more side surfaces 30a, 30b (collectively side surfaces 30) and a planar top 20. In some embodiments, each groove 28 may have one or more substantially planar landings 25 joining the corresponding adjacent structures 10a. In some embodiments, a first light transmissive layer 40 may substantially cover the one or more side surfaces 30 / 30a / 30b, landings 25, and a substantially planar top surface 20. In some embodiments, a cover layer 50 may substantially cover at least the one or more side surfaces 30 / 30a / 30b. In some embodiments, cover layer 50 may have an average thickness of greater than about 0.05 microns, or greater than about 0.1 microns, or greater than about 0.15 microns, or greater than about 0.2 microns, or greater than about 0.25 microns, or greater than about 0.3 microns, or greater than about 0.35 microns, or greater than about 0.4 microns, or greater than about 0.45 microns, or greater than about 0.5 microns, or greater than about 0.55 microns, or greater than about 0.6 microns, or greater than about 0.65 microns, or greater than about 0.7 microns, or greater than about 0.75 microns, or greater than about 1.0 microns, or greater than about 1.25 microns, or greater than about 1.5 microns, or greater than about 2 microns, or greater than about 2.5 microns, or greater than about 3 microns. In some embodiments, the cover layer may have an average thickness of from about 0.05 microns to 1.5 microns, or from about 0.10 microns to 1.0 microns, or from about 0.50 microns to 1.2 microns, or from about 0.20 microns to 0.50 microns. In some embodiments, the light absorbing cover layer 50 may have an optical density of greater than about 0.1, or greater than about 0.2, or greater than about 0.4, or greater than about 0.6, or greater than about 0.8, or greater than about 1, or greater than about 1.1, or greater than about 1.2, or greater than about 1.3, or greater than about 1.5, or greater than about 2, or greater than about 2.5, or greater than about 3, or greater than about 3.5, or greater than about 4, or greater than about 4.5, or greater than about 5, or greater than about 5.5, or greater than about 6. In some embodiments, the optical density is less than about 3.0, or less than about 2.5, or less than about 2.0. In some embodiments the optical density is between 0.5 and 2.5, or between 1.0 and 2.0 or between 1.2 and 1.8. In some embodiments, the cover layer may be light absorbing. In some such embodiments, the light absorbing cover layer may include a polyelectrolyte. In some such embodiments, the light absorbing cover layer may include a plurality of light absorbing particles (e.g., the light absorbing particles may contain one or more of a dye, a pigment, and a carbon black). FIG.2B is an SEM micrograph of a sample of a light control film according to the present description (i.e., an actual image showing an embodiment similar to the embodiment described in FIG.1 and FIG.2A). FIG.2B shows light transmissive body 10 and a portion of one of the plurality of structures 10a (along the right side of the image). First light transmissive layer 40 is a thin layer on side surfaces 30 / 30a / 30b, landings 25, and a planar top surface 20 (although planar top surface is not visible in this micrograph). In some embodiments, a cover layer 50 covers the first light transmissive layer 40 on the one or more side surfaces 30 / 30a / 30b, but substantially does not cover landings 25 (or planar top surface 20). As seen in the micrograph of FIG.2B, the average arithmetic surface roughness of the first light transmissive layer 40 on side surfaces 30 / 30a / 30b, Ra2, is relatively smooth, while the average arithmetic surface roughness of the first light transmissive layer 40 on landings 25 (and planar top surface 20), Ra1, is significantly higher (higher roughness visible on landing 25 in the micrograph of FIG.2B). Details on the relative magnitudes of Ra1 and Ra2 are described elsewhere herein. FIGS.3A and 3B presents contrasting top and side profile views of a light control film respectively, such as the embodiment of light control film 300 shown in FIG.1. It should be noted that, in the top view of light control film 300 shown in FIG.3A, planarizing overcoat 90 has been omitted to better show the relationship between structures 10a, first light transmissive layer 40, and cover layer 50. As shown in the embodiment of FIGS.3A and 3B, the plurality of structures 10a may include linear structures extending substantially across a width direction of the light control film (e.g., along the x-direction shown in FIG.3A) and arranged along an orthogonal length direction of the light control film (e.g., extending along the y-direction). In some embodiments, each linear structure 10a may be separated from each adjacent linear structure by a groove 28. As can be seen in the top view of FIG.3A and the side view of FIG.3B, first light transmissive layer 40 covers and is visible over the landings 25 and substantially planar tops 20 of the structures but is covered by cover layer 50 on the one or more side surfaces 30 / 30a / 30b. In this embodiment, a type of louver film may be created with areas of light transmission (landings 25 and planar tops 20) alternating with areas of light blocking / absorbing (side surfaces 30 / 30a / 30b). In some embodiments, the one or more side surfaces 30 / 30a / 30b may be substantially vertical (e.g., oriented along the y-direction shown in FIG.3B) and, because they are covered by cover layer 50, these substantially vertical, light blocking / absorbing “walls” can be used to direct light through the light control film 300 (e.g., to columnize or otherwise direct the light being transmitted). FIG.4 provide details on the structure of a light control film, including angles and widths of various features, according to an embodiment of the present description. In particular, FIG.4 is provided to illustrate how the structure of the light control film may be modified / adjusted to meet the design of a light control film which meets a specific set of requirements. It should be noted that the elements of light control film 300 in FIG.4 which share like numbers with elements of other figures herein shall be assumed to have the same function unless otherwise specified. Accordingly, these elements may not be described again in this discussion. The performance of a light control film, such as a louver film with alternating areas of light transmission and light blocking / absorption, depends on the specific arrangement and configuration of the elements of the light control film. Changes in the angles of the “walls” in a louver film, the spacing between adjacent louvers, the “period” of the louvers, the depth of the channel between louvers, and the shape of the channels and walls which make up the light control film are all things that can be adjusted to change the performance of the light control film. For example, looking at light control film 300 shown in FIG.4, if we assume first that light transmissive body 10 (including structures 10a), first light transmissive layer 40, and planarizing overcoat 90 substantially transmit light, then the configurations of the “walls” created by the cover layer 50 on the side surfaces 30 / 30a / 30b define how the light control film performs. The orientation of cover layer 50 (the “walls” of the light control film 300) may, for example, depend on the angles θ1 and θ2 of side surfaces 30a, 30b. The height hcof the cover layer 50 may also have an effect on the performance (i.e., the length in the z-direction, or thickness direction of the light control film 300, of the space defined between the “walls” of the cover layer 50 may determine the amount of columnizing done as light passes through the space). In some embodiments, hcmay be about 5 microns, or about 10 microns, or about 15 microns, or about 20 microns, or about 30 microns, or about 40 microns, or about 50 microns, or about 60 microns, or about 75 microns, or about 100 microns, or about 150 microns, or about 200 microns, or about 250 microns. In should be noted that, in some embodiments, cover layer 50 on side surfaces 30 may not extend all the way to planar top surface 20. The pitch, p1, or the distance between ends of one structure 10a and an adjacent one, including the landing 25 and planar top 20, and the widths of the structures 10a, landings 25, and planar tops 20 may also have effects on the performance of light control film 300. In some embodiments, p1 may be about 20 microns, or about 30 microns, or about 40 microns, or about 50 microns, or about 60 microns, or about 75 microns, or about 100 microns, or about 150 microns, or about 200 microns, or about 250 microns. For example, in some embodiments, a typical structure 10a may have a first width w1 near the base of the structure and a second width w2 near the top of the structure. In some such embodiments, w1 and w2 may be substantially equal (e.g., within about 10% of each other). In some other embodiments, w1 may be greater than w2. Similarly, the “channels” formed between adjacent structure 10a may have width w3 near the base of the channel (near landing 25) and width w4 near the top of the channel. For the purposes of this discussion, “top” shall mean a surface or space higher on the page in the z-direction shown, and “bottom” shall mean a surface or lower on the page in the z-direction. In some embodiments, w3 and w4 may be substantially equal (e.g., within about 10% of each other). In some other embodiments, w4 may be greater than w3. In some embodiments, it may be advantageous for the planarizing overcoat to be symmetric with the transmissive layer. In such an embodiment, w3 may be about equal to w2 and w1 may be about equal to w4. All of these features discussed herein affect the “channels” they define, and the shape, size, spacing, and orientation of these channels can be used to control the “cutoff angle” of the channels (i.e., the angle beyond which light passing through light control film 300 is blocked. FIGS.5A-5B show representations of embodiments of the light transmissive and cover layers of a light control film, such as light control film 300 of FIG.1A. FIGS.5A-5B are schematic drawings and not intended to be accurate to scale or proportion. Each of FIGS.5A and 5B may represent an embodiment of one of the first light transmissive layer 40 (shown here as 40’) or cover layer 50 (shown here as 50’). In some embodiments, at least one of the first light transmissive layer 40’ and cover layer 50’ may be porous comprising a plurality of pores 40’a, 50’a. For example, pores 40’a, 50’a may be created by interstitial spaces between particles within the first light transmissive layer 40’ and / or cover layer 50’. In some such embodiments, a volume fraction of the pores may be greater than 0.2, or greater than 0.3, or greater than 0.4, or greater than 0.5, or greater than 0.6, or greater than 0.7. In some embodiments, an average size of pores 40’a, 50’a may be less than about 50 nm, or less than about 40 nm, or less than about 30 nm, or less than about 20 nm, or less than about 10 nm, or less than about 5 nm, or less than about 1 nm. In some embodiments, pores 40’a, 50’a may be at least partially filled with the material of planarizing overcoat (such as overcoat 90 of claim 1). FIG.5B shows a representation of an embodiment of either a light transmissive layer 40” or a cover layer 50” (shown in both a top view and a side cutaway view) which is physically discontinuous and which includes a plurality of spaced apart islands 40”a, 50”a separated by gaps 41”a, 51”a. FIGS.6A-6D illustrate display systems including a light control film, such as light control film 300 of FIG.1A. Like-numbered elements in FIGS.6A through 6D shall be assumed to have the same function unless specifically stated otherwise herein, and therefore descriptions of these shared elements may not be repeated. Looking at FIG.6A, in some embodiments, display system 400 may include a light control film 300 disposed above a display 70 configured to form an image 71. In some embodiments, the light control film 300 may be disposed between the viewer 80 and display 70. The light control film 300, in some embodiments, may be disposed between and include transparent substrate layers 72 and 73. In some embodiments, the display system may include optional cover glass layer 76 which may or may not be optically coupled to the surface of the display system 70. In some embodiments, where cover glass 76 is optically coupled to display 70, the coupling layer may comprise an optically clear adhesive (not shown) disposed between the surface of the display 70 and cover window or cover glass 76. In some embodiments, the light control assembly 305 may be disposed above the display with an airgap between the light control assembly and the cover glass 76 and / or display 70. The display assembly can be any type of display, such as an LCD display, OLED display, micro-LED display, etc. In some embodiments the light control film is optically coupled to the display or cover glass using an optically clear adhesive. In some embodiments, the light control film assembly may be optically coupled to the display 70 and / or cover glass 76 with a self-wetting optically clear and repositionable removable adhesive layer. Looking at FIG.6B, in some embodiments, display system 401 may include a light control film assembly 306 disposed behind an LCD display 70 having configured to form an image 71 on an emission plane of display 70. In some embodiments, the light control film assembly 306 may be disposed between LCD display 70 and a backlight 100. In some embodiments, the light control assembly 306 may include light control film 300 and a reflective polarizer 77. In some embodiments, the light transmissive body 10 of light control film 300 may be disposed on a substrate 72 (e.g., a polycarbonate substrate). In some embodiments, the planarization layer 90 may be bonded to reflective polarizer 77 with a first adhesive layer 78a (e.g., a UV cross-linked adhesive). In some embodiments, the opposite side of the reflective polarizer 77 (i.e., the side opposite planarization layer 90) may be bonded to another substrate 79 (e.g., a polycarbonate substrate) with a second adhesive layer 78b (e.g., a UV cross-linked adhesive). In some embodiments, the first adhesive layer 78a and second adhesive layer 78b may include the same material (e.g., same adhesive). In some embodiments, a first brightness enhancement film 105 may separate backlight 100 and the light control assembly 306. In some embodiments, a second brightness enhancement film 106 may be paired with first brightness enhancement film 105 (e.g., crossed prism films). In some embodiments, there may be air gaps between the brightness enhancement films 105 and 106. In some embodiments, the two crossed brightness enhancement films may be optically coupled with an adhesive. In some embodiments, there may be air gaps between brightness enhancement films backlight 100 and brightness enhancement films 105 and 106. In some embodiments, there may be air gaps between light control assembly 306 and brightness enhancement films 105 and 106. In some embodiments, display system 401 may include a cover glass 76 which may or may not be optically coupled to the surface of the display system 70. In embodiments, where cover glass 76 is optically coupled to display 70, a coupling layer may comprise an optically clear adhesive (not shown) disposed between the surface of the display 70 and cover glass 76. In some embodiments, display 70 may be disposed between the viewer 80 and light control film assembly 306. FIG.6C shows an integrated display system 402 with an OLED assembly 700 and light control film assembly 307. In some embodiments, light transmissive body 10 of light control film 300 is disposed on a substrate 72 (e.g., a polycarbonate substrate). In some embodiments, the planarization layer 90 may bonded to cover glass 76 (e.g., a glass or plastic pane) with an optically clear adhesive 85. In some embodiments, light control film assembly 307 may be bonded to OLED assembly 700 with an optically clear adhesive 84. In some embodiments, optically clear adhesive 84 may be optically bond / optically couple substrate 72 and a polarizer 83 (e.g., a circular polarizer). In some embodiments, OLED assembly 700 may include OLED display 70 with OLED emission layer 71a. A thin film encapsulation layer 81 may, in some embodiments, be disposed over OLED emission layer 71 and seal the OLED emissive layer 71 against air, moisture, or other environmental factors. In some embodiments, OLED assembly 700 may include an in-cell touch sensor layer 82 and an optically clear adhesive 88 which may optically bond the in-cell touch layer 82 to polarizer layer 83 (e.g., a circular polarizer). In some embodiments, light control film 300 may be disposed between viewer 80 and OLED display 70. The optically clear adhesive layers shown in the embodiments of Figures 6A - 6C may have any useful thickness. In some embodiments, the optically clear adhesive may have a thickness of from about 10 microns to about 400 microns, or from about 10 microns to about 300 microns, or from about 10 microns to about 150 microns, or from about 25 microns to about 125 microns, or from about 50 microns to about 100 microns. In some embodiments, adhesive layer 85 may have a haze level from about 0.1% to about 70%, or from about 0.1% to about 60%, or from about 0.1% to about 55%, or from about 0.1% to about 50%, or from about 0.1% to about 40%, or from about 2% to about 30%, or from about 5% to about 20%. In some embodiments, adhesive layer 95 may be an optically clear adhesive. In some embodiments, an optically clear adhesive layer used to bond the cover glass to the display systems 400, 401 and 402 may include laminating adhesives which have the properties of pressure sensitive adhesives. In some embodiments, optically clear adhesive layers may be a liquid applied adhesive, applied by any suitable method, which is cured to a polymeric state after bonding of two layers. In some embodiments, a laminating adhesive may have additional reactive functionality which can be reacted in a secondary curing process. In some embodiments, the display systems 400, 401, and 402 may be a curved display system 407 such as that represented in FIG.6D. In some embodiments, curved display system 407 may be curved along at least one direction (e.g., curved along the x-axis of FIG.6B). Similarly, in some embodiments, light control film 300 and light control film assemblies 305 may be a curved light control film 307, also represented by the schematic drawing of FIG.6D. In such embodiments, curved light control film 307 may be curved along at least one direction (e.g., the x-axis as shown in FIG. 6D). FIG.7 illustrates an embodiment of a method of making a light control film, according to the present description. The method includes the steps of: (A) providing a substantially light transmissive film 10 including a structured first major surface 11 and an opposing second major surface 12, the structured first major surface 11 including a plurality of structures 10a separated by one or more grooves 28 extending in a thickness direction of the light control film 10 (e.g., the z-direction shown in FIG.7), each structure 10 including one or more side surfaces 30 / 30a / 30b, each groove 28 having one or more substantially planar landings 25 joining the corresponding structures, each of the one or more side surfaces 30 / 30a / 30b making an angle with an adjacent landing 25 of the one or more landings 25, or with the second major surface 12, of greater than about 60 degrees; (B) coating the structured first major surface 11 with a light transmissive layer 40, the light transmissive layer 40 covering at least 80% of each of the plurality of structures 10a and the one or more grooves 28 and a plurality of first inorganic particles (e.g., first inorganic particles 41 of FIGS. 1B and 1C) at a volume loading of greater than about 5%; (C) coating the light transmissive layer 40 with a cover layer 50 so that at least 80% of the light transmissive layer 40 is covered by cover layer 50; and (D) etching cover layer 50 using a directional first etching process 700 (e.g., reactive ion etching, or RIE) to remove more than about 80% of cover layer 50 from the one or more landings 25 but less than about 40% of cover layer 50 from each of the one or more side surfaces 30 / 30a / 30b, resulting in the light transmissive layer 40 coated on the one or more landings 25 and the one or more side surfaces 30 / 30a / 30b having respective arithmetic average surface roughnesses Ra1 and Ra2, wherein Ra1 is greater than Ra2 (in some embodiments, Ra2 may be greater than zero). In some embodiments, the method of making a light control film may further include covering and substantially planarizing the structured first major surface with a planarizing overcoat 90 (not shown in FIG.7 but shown in at least FIG.1A). FIG.8 includes a TEM micrograph of an embodiment of a light control film having a first light transmissive layer 40 and a second light transmissive layer 45, according to the present description. The microscope image of FIG.8 shows a close-up view of an area of light control film 300 shown in the dashed rectangle region in the bottom half of the figure. In some embodiments, light control film 300 may include a light transmissive body 10 with structures 10a separated by one or more grooves 28, a first light transmissive layer 40, a light absorbing layer 50, a planarizing overcoat 90. In some embodiments, light transmissive body 10 may have a plurality of alternating linear first 20 and second 30 facets extending along a first direction (e.g., the y-axis shown in FIG.3A) and arranged along a different second direction (e.g., the x-axis of FIG.3A). In some embodiments, first light transmissive layer 40 may have a first average thickness of greater than about 0.005 microns, or greater than about 0.01 microns, or greater than about 0.02 microns, or greater than about 0.03 microns, or greater than about 0.04 microns, or greater than about 0.05 microns, or greater than about microns, 0.08 microns, or greater than about 0.1 microns, or greater than about 0.15 microns, or greater than about 0.2 microns and coated on at least 80%, or at least 85%, or at least 90%, or at least 95% of each of the first 20 and second 30 facets. In some embodiments, the light transmissive layer 40 may include a plurality of first inorganic particles (e.g., particles 41 of FIGS.1B and 1C) including a first inorganic material (e.g., Si). In some embodiments, light absorbing layer 50 may have an average thickness of greater than about 0.05 microns, or greater than about 0.1 microns, or greater than about 0.15 microns, or greater than about 0.2 microns, or greater than about 0.25 microns, or greater than about 0.3 microns, or greater than about 0.35 microns, or greater than about 0.4 microns, or greater than about 0.45 microns, or greater than about 0.5 microns, or greater than about 0.55 microns, or greater than about 0.6 microns, or greater than about 0.65 microns, or greater than about 0.7 microns, or greater than about 0.75 microns, or greater than about 1.0 microns, or greater than about 1.25 microns, or greater than about 1.5 microns, or greater than about 2 microns, or greater than about 2.5 microns, or greater than about 3 microns and coated on at least 70%, or at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95% of the light transmissive layer 40 on each of side surfaces 30 / 30a / 30b and on at most 30%, or at most 25%, or at most 20%, or at most 15%, or at most 10%, or at most 5% of the light transmissive layer 40 on each of the landings 25 (and, when present, on each of the substantially planar tops 20). In some embodiments, planarizing overcoat 90 covers light absorbing layer 50 and substantially planarizes structured first major surface 11. In some embodiments, for each of at least some of the side surfaces 30 / 30a / 30b, landings 25, and planar tops 20, a second light transmissive layer 45 (shown in electron micrograph as a faint line between cover layer 50 and overcoat 90) may be disposed between planarizing overcoat 90 and light absorbing layer 50. In some embodiments, second light transmissive layer 45 may include the first inorganic material and may have a second average thickness that is less than the first average thickness. In some embodiments, the second average thickness may be less than about 20 nm, or less than about 10 nm, or less than about 5 nm.. In some embodiments, the second light transmissive layer 45 may be discontinuous. Finally, FIGS.9A-9D illustrate various alternate embodiments of a light control film, according to the present description. FIG.9A shows an alternate embodiment of a light control film 308 where the one or more side surfaces 30 of the structures 10a of light transmissive body 10 include a first side surface 30a and a second side surface 30b, but there is no substantially planar top surface joining side surfaces 20a and 30b. That is, in this embodiment, the first side surface and the second side surface meet at and form a peak 35 (e.g., of a triangular linear prism). The remaining figures, FIGS.9B, 9C, and 9D, show alternate views of an embodiment of a light control film 308 where the structures 10a (shown as dashed lines, as structures 10a would not be visible covered by light transmissive layer 40) are embodied as a plurality of posts arranged along a width direction (e.g., the Y-direction of FIG.9B) and an orthogonal length direction (e.g., the X- direction) of light control film 309. In some embodiments, at least a portion of the posts in the plurality of posts may be substantially surrounded by the one or more landings 25. The landings 25 may be found between adjacent posts / structures 10a in grooves 28 which may extend in both the width and length direction. Each of the side surfaces 30 of the posts / structures 10a (including the light transmissive layer 40 surrounding posts 10a) may be substantially covered in cover layer 50 (but landings 25 or planer tops 20 may be substantially uncovered by cover layer 50). FIG.9C shows a cross-sectional view of light control film 309 where the cross-section is taken at the plane marked AA in FIG.9B. In some embodiments, the one or more side surfaces 30 may be substantially orthogonal to the second major surface 12 of light transmissive body 10. Structures / posts 10a may, in some embodiments, be in the shape / form of rectangular prisms (as seen in FIGS.9B and 9D) but may also be any appropriate shape, including, but not limited to, a cylinder or a triangular prism. FIG.9D provides an additional perspective view of an embodiment of light control film 309 featuring posts 10a which are rectangular prisms arranged in a regular, two- dimensional array of posts 10a. In some embodiments, the arrangement of posts 10a may be irregular (e.g., random) across the length and width directions. As seen best in FIG.9D, in an embodiment such as light control film 309 featuring posts instead of linear prisms, the cover layer 50 may substantially cover the substantially vertical sides 30 of posts / structures 10a but substantially planar landings 25 and substantially planar tops 20 may be substantially uncovered by cover layer 50. Examples Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. Materials Used in the Examples Abbreviation Description Photomer 6010 Aliphatic urethane diacrylate obtained under the tradename PHOTOMER 6010 from IGM Resins (Charlotte, NC) SR602 Ethoxylated (10) bisphenol A diacrylate obtained from Sartomer (Exton, PA) SR601 Ethoxylated (4) bisphenol A diacrylate obtained from Sartomer TMPTA Trimethylolpropane triacrylate obtained from Cytec Industries (Woodland Park, NJ) PEA (ETERMER 2010) Phenoxyethyl acrylate obtained under the trade designation ETERMER 2010 from Eternal Chemical Co., Ltd., Kaohsiung, Taiwan Darocur 1173 2-Hydroxy-2-methylpropiophenone photoinitiator obtained under the trade designation DAROCUR 1173 from BASF (Florham Park, NJ) TPO Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide photoinitiator obtained under the trade designation DAROCUR TPO from BASF I1035 Antioxidant obtained under the trade designation IRGANOX 1035 from BASF O2Oxygen gas (UHP compressed) obtained from Oxygen Service Company, St. Paul, MN PDAC Polydiallyldimethylammonium chloride, obtained under the trade designation DEHYQUART CC6 from BASF SiO2-5nm Anionic silicon dioxide nanoparticles with average particle size of 5 nm and ammonia stabilized, obtained under the trade designation NALCO 2326 from Nalco Water, Naperville, IL. SiO2-44nm Anionic silicon dioxide nanoparticles with average particle size of 44 nm and ammonia stabilized, obtained under the trade designation NALCO DVSZN004 from Nalco Water. TiO2Anionic titanium dioxide nanoparticles, tetramethylammonium stabilized in water, obtained from 3M (St. Paul, MN). Prepared similarly to procedure reported in US 9,481,583 (Krogman). VMT Vermiculite clay suspension in water obtained under the tradename MICROLITE 963++ from Dicalite Management Group, Inc. (West Conshohocken, PA) TMACl Tetramethylammonium chloride, 50 wt% in water obtained from Sachem (Austin, TX). TMAOH Tetramethylammonium hydroxide, 2.38 wt% in water obtained from Alfa Aesar (Ward Hill, MA) SC72 Cationic polyurethane dispersion obtained under the tradename SANCURE 20072 from Lubrizol (Wickliffe, OH). EXPCB Anionic, surface-modified carbon black dispersion obtained from Cabot Corp., Boston, MA CR3090 Anionic, styrene-acrylic emulsion obtained under the tradename CARBOSET CR-3090 from Lubrizol. NaCl Sodium chloride, obtained as a 25% solids solution in water from Univar Solutions, Houston, TX PL92 Non-ionic surfactant, obtained under the trade designation, PLURONIC L- 92 from BASF O2, 99.99% Oxygen Gas from Air Gas, Roseville, MN Method for Cast-and-Cure Microreplication to Make Clear Channel Film A diamond (29.0 μm tip width, 3 ^ included angle, 87 μm deep) was used to cut a metal tool having a plurality of parallel linear grooves. The grooves were spaced apart by a pitch of 62.6 microns. Resin A was prepared by mixing the materials in Table 1 below. Table 1: Composition of Resin A used to make clear channel film Material Parts by Weight Photomer 6010 60 SR602 20 SR601 4.0 TMPTA 8.0 PEA (Etermer 2010) 8.0 Darocur 1173 0.35 TPO 0.10 I1035 0.20 A “cast-and-cure” microreplication process was carried out with Resin A and the tool described above. The line conditions were: resin temperature 150 ^F, die temperature 150 ^F, coater IR 120 ^F edges / 130 ^F center, tool temperature 100 ^F, and line speed 70 fpm. Fusion D lamps, with peak wavelength at 385 nm, were used for curing and operated at 100% power. The resulting microstructured film comprised a plurality of protrusions / ribs separated by channels / valleys. The base layer was PET film (3M, St. Paul, MN), having a thickness of 2.93 mils (74.4 microns). The side of the PET film that contacts the resin was primed with a thermoset acrylic polymer (Rhoplex 3208 available from Dow Chemical, Midland, MI). The land layer of the cured resin had a thickness of 8 microns. The protrusions of the microstructured film are a negative replication of the grooves of the tool. The protrusions have a wall angle of 1.5 degrees resulting in the protrusions being slightly tapered. The channels of the microstructured film are a negative replication of the uncut portions of the tool between the grooves. Method for Preparing Layer-by-Layer Etch Stop Coating Solutions Two different cationic polymers were used for etch stops. A PDAC coating solution was made with 0.32% solids DEHYQUART CC6 and 0.14 wt% of TMAOH (2.38% solids) in deionized (DI) water. A PEI coating solution was made with 0.1% solids LUPASOL WF in DI water without any added salt or pH adjustment. Multiple different anionic metal oxide particles were used for etch stops. A SiO2-5 nm coating solution was made with 1.0% solids NALCO 2326, 48 mM TMACl, and 2.7 wt% of TMAOH (2.38% solids) in DI water, while a SiO2-44 nm coating solution was made with 1.0% solids NALCO DVSZN004, 48 mM TMACl, and 2.7 wt% of TMAOH (2.38% solids) in DI water. A TiO2coating solution was made with 1.0% solids TiO2, 65 mM TMACl, and 0.76 wt% of TMAOH (2.38% solids) in DI water. A VMT clay coating solution was made with 1.0% solids MICROLITE 963A+ in DI water without any added salt or pH adjustment. Method to Coat a Layer-by-Layer Etch Stop (“Light Transmissive Layer”) – Continuous Etch stops were deposited conformally on the clear channel film via layer-by-layer (LbL) deposition on a coater as described in US Pat. No.10,926,289 (Kawakami et al.). The etch stops comprised six bilayers, denoted as (Cation / Etch Stop Anion)6. The Cation and Etch Stop Anion solutions were separately coated onto the microstructured clear channel film with a #4 Mayer Rod fed from a liquid delivery manifold at a flow rate of about 200 mL / min at each coating station. Excess coating solution was removed from the web after each deposition step with air-knives gapped at 40 mil to the web with pressure of about 35 psi. Line speed was 50 feet per minute. Method to Coat a Layer-by-Layer Etch Stop (“Light Transmissive Layer”) – Batch Etch stops were deposited conformally on the clear channel film via layer-by-layer (LbL) deposition on a coater purchased from Svaya Nanotechnologies, Inc. (Sunnyvale, CA) and modeled after the system described in US 8,234,998 (Krogman et al.) as well as Krogman et al. Automated Process for Improved Uniformity and Versatility of Layer-by-Layer Deposition, Langmuir 2007, 23, 3137-3141. The apparatus comprises pressure vessels loaded with the coating solutions. Spray nozzles with a flat spray pattern (from Spraying Systems, Inc., Wheaton, Illinois) were mounted to spray the coating solutions and rinse water at specified times, controlled by solenoid valves. The pressure vessels (Alloy Products Corp., Waukesha, WI) containing the coating solutions were pressurized with nitrogen to 30 psi, while the pressure vessel containing deionized (DI) water was pressurized with air to 30 psi. Flow rates from the coating solution nozzles were each 10 gallons per hour, while flow rate from the DI water rinse nozzles were 40 gallons per hour. The substrate to be coated (9”x10”) was adhered at the edges with epoxy (Scotch-Weld epoxy adhesive, DP100 Clear, 3M Company, St. Paul, MN) to a glass plate (12” x 12” x 1 / 8” thick) (Brin Northwestern Glass Co., Minneapolis, MN), which was mounted on a vertical translation stage and held in place with a vacuum chuck. In a typical coating sequence, the polycation (e.g., PDAC) solution was sprayed onto the substrate while the stage moved vertically downward at 76 mm / sec. Next, after a dwell time of 12 sec, the DI water was sprayed onto the substrate while the stage moved vertically upward at 102 mm / sec. The substrate was then dried with an airknife at a speed of 3 mm / sec. Next, the polyanion (e.g., silica nanoparticle) solution was sprayed onto the substrate while the stage moved vertically downward at 76 mm / sec. Another dwell period of 12 sec was allowed to elapse. The DI water was sprayed onto the substrate while the stage moved vertically upward at 102 mm / sec. Finally, the substrate was then dried with an airknife at a speed of 3 mm / sec. The above sequence was repeated to deposit a desired number of “bi-layers” denoted as (Cation / Etch Stop Anion)nwhere n is the number of bi-layers. The coated substrate (e.g., polymer film) was stripped off of the glass prior to subsequent processing. The coating on the glass can be used for further characterization. Method to Coat a Light Absorbing Cover Layer - Continuous A black, light-absorbing cover layer was coated conformally on a clear channel film (either without (Comparative Example) or with (Examples) an underlying etch stop) via layer-by-layer (LbL) deposition on a coater as described in US Pat. No.10,926,289 (Kawakami et al.). Three separate coating solutions were prepared: Cation, Cover Layer Core Anion, and Cover Layer Clad Anion. The Cation solution was 2.5% solids SC72 with 200 mM NaCl and 0.1% PL92 in DI water. The Cover Layer Core Anion solution was 2.5% solids EXPCB with 50 mM NaCl and 0.1% PL92 in DI water. The Cover Layer Clad Anion solution was 4.0% solids CR3090, 0.5% solids EXPCB with 50 mM NaCl and 0.1% PL92 in DI water. The light-absorbing coating construction comprised six bilayers of Cation / Cover Layer Clad Anion, denoted as (Cation / Cover Layer Clad Anion)6, followed by four bilayers of Cation / Cover Layer Core Anion, denoted as (Cation / Cover Layer Core Anion)4, followed by six bilayers of Cation / Cover Layer Clad Anion, denoted as (Cation / Cover Layer Clad Anion)6, for a total of sixteen bilayers. Microstructured film was threaded through the coating line. The coating solutions were separately coated onto the microstructured film with a #4 Mayer Rod fed from a liquid delivery manifold at a flow rate of about 200 mL / min at each coating station. Excess coating solution was removed from the web after each deposition step with air-knives gapped at 40 mil to the web with pressure of about 35 psi. Line speed was 50 feet per minute. Thickness of the LbL coating, determined by analyzing an SEM image of the coating on a sidewall of the clear channel film with ImageJ software, was 954 ± 19 nm. Method to Coat a Light Absorbing Cover Layer - Batch A black, light-absorbing cover layer was coated conformally on a clear channel film using the equipment described in the “Method to Coat a Layer-by-Layer Etch Stop (“Light Transmissive Layer”) – Batch”. Two separate coating solutions were prepared: Cation and Cover Layer Core Anion. The Cation solution was 1.0% solids SC72 with 200 mM NaCl and 0.1% PL92 in DI water. The Cover Layer Core Anion solution was 1.0% solids EXPCB with 50 mM NaCl and 0.1% PL92 in DI water. The light-absorbing coating construction comprised six bilayers of Cation / Cover Layer Core Anion, denoted as (Cation / Cover Layer Core Anion)6. Thickness of the LbL coating, determined by analyzing an SEM image of the coating on a sidewall of the clear channel film with ImageJ software, was 422 ± 36 nm. Method to Selectively Remove Portions of the Light Absorbing Cover Layer Reactive ion etching (RIE) was performed in a home-built parallel plate capacitively coupled plasma reactor. The chamber has a central cylindrical powered electrode with a surface area of 18.3 ft2. After placing the micro-structured film on the powered electrode, the reactor chamber was pumped down to a base pressure of less than 0.3 Pa (2 mTorr). O2(oxygen) gas was flowed into the chamber at a rate of 1000 SCCM. Treatment was carried out using a plasma by coupling RF power into the reactor at a frequency of 13.56 MHz and an applied power of 8000 watts. Treatment time was controlled by moving the microstructured film through the reaction zone. A first treatment time of 150 seconds was completed on all samples by moving the film through the chamber at a rate of 2 ft / min. A second treatment time was applied to the same surface by moving the same section of film through the chamber at a rate of 1 ft / min. Together, this resulted in a full treatment time of 450 seconds. Following the treatment, the RF power and the gas supply were stopped, and the chamber was returned to atmospheric pressure. Intermediate treatment times from 150 to 450 s were collected from the gradient etch time down the length of the sample. Additional information regarding materials and processes for applying cylindrical RIE and further details around the reactor used can be found in US8460568 B2. Method for Measuring %Transmission (%T) %T was measured using a BYK (Geretsried, Germany) Haze-Gard Plus instrument with the structured side of the sample facing the light source. Method for Acquiring Scanning Electron Microscopy (SEM) Images Samples were freeze fractured with liquid nitrogen. Imaging was done with a Hitachi S4700 Field Emission microscope. Coating thickness values were determined using ImageJ software, a Java-based image processing program developed at the National Institutes of Health. SEM was used to measure thickness of the light transmissive layer (i.e., etch stop) and the light-absorbing cover layer. Method to Backfill Resin A was heated to 65°C in an oven. A microstructured film sample, following the reactive ion etching step, was taped to an aluminum plate, and then placed on a hot plate heated to 65°C. Resin A was pipetted between the microstructured film surface and a piece of primed, 3 mil- thick PET film placed on top; this construction was then sent through a GBC Catena 35 hot roll laminator heated to 150°F with a speed of 5 ft / min. The construction was then sent through a Heraeus (Hanau, Germany) belt conveyer UV processor (Model# DRS(6)) with an ‘H’ bulb at 500 Watt / inch power three times at a conveyer speed of 50 ft / min. Method for Acquiring Transmission Electron Microscopy (TEM) Images Samples for TEM analysis were room-temperature ultra-microtomed. Cut thickness ranged between 100 and 130 nm. Microtomy-cut direction was chosen to be parallel or nearly parallel to a majority of the interfaces. TEM analysis was performed on a FEI-Osiris TEM, operating at 200 kV. The STEM imaging mode was used. Bright Field (BF), Dark Field (DF), and High Angle Annular Dark Field (HAADF) images were acquired. X-ray microanalysis was performed using a Bruker Super-X quad x-ray SDD (silicon drift detector) and accompanying Espirit quantitative analysis software system (see, e.g., FIG.8). Method for Determining Weight% of Inorganic Particles in LbL Etch Stop Coatings A layer-by-layer (LbL) spray coater, purchased from Svaya Nanotechnologies (Sunnyvale, CA) and modeled after the system described in US 8,234,998 (Krogman et al.) as well as Krogman et al. Automated Process for Improved Uniformity and Versatility of Layer-by-Layer Deposition, Langmuir 2007, 23, 3137-3141, was used to deposit LbL etch stop coatings on a 12”x12”x1 / 8” glass plate. The coatings were scraped off the plate with a razor blade. The powder samples were analyzed using a TA Instruments Discovery Thermogravimetric Analyzer (TGA) in HiRes mode. The sample was subjected to a heating profile ranging from room temperature (~30 °C) to 700 °C in a nitrogen atmosphere, with a heating rate of 20.0 °C / min and a resolution setting of 4.0. Under these conditions, the instrument heats the sample until weight loss is detected, at which point the temperature stabilizes until weight loss diminishes, and then heating recommences. At 700°C the atmosphere was then switched to air and the HiRes heating ramp was continued to 800° C. The weight% residue at 800° C was taken as the weight % of inorganic particles (e.g., metal oxide) in the coating samples. Method for Determining Porosity of LbL Etch Stop Coatings Porosity (i.e., volume % air) of the LbL etch stop coatings was measured with an in situ spectroscopic ellipsometry method, similar to what was reported in Lee et al. JACS 2009 Vol.131 p. 671-679. The spectroscopic ellipsometer was an M-2000 instrument and the software was WVASE32, both purchased from J.A. Woollam Co., Inc. (Lincoln, NE). Briefly, LbL etch stop coatings deposited on silicon wafers using the “Method to Coat a Layer-by-Layer Etch Stop (Light Transmissive Layer) – Batch” were placed in a custom-made quartz cell with windows perpendicular to the incident and reflected light from the ellipsometer at a measurement angle of 70 degrees. Measurements were taken in ambient air and in a DI water environment (ambient). Etch stop coatings were modeled as Cauchy layers. Porosity was calculated using the Lorentz-Lorenz mixing rule for refractive indices. Method for Determining Volume% of Inorganic Particles in LbL Etch Stop Coatings Volume % of inorganic particles in the LbL etch stop coatings was calculated from the weight % values determined in the “Method for Determining Weight% of Inorganic Particles in LbL Etch Stop Coatings” and the porosity values determined in the “Method for Determining Porosity of LbL Etch Stop Coatings”, assuming a density of SiO2to be 2.05 g / cc, density of TiO2to be 3.90 g / cc, and density of PDAC polymer to be 1.00 g / cc. Method for Determining Refractive Index of the LbL Etch Stop Coatings Refractive index of the LbL Etch Stop Coatings was determined using a Filmetrics (San Diego, CA) F10-AR reflectometer with hardcoat (HC) mode for coatings deposited on glass plates using the “Method to Coat a Layer-by-Layer Etch Stop (“Light Transmissive Layer”) – Batch”. Method for Measuring the Luminance Profile from a Diffuse Light Source A sample of film was placed on a Lambertian light source. When the light transmissive regions are tapered, the film is positioned such that the widest portion of the tapered regions are closer to the light source. An Eldim L80 conoscope (Eldim S.A., Herouville-Saint-Clair, France) was used to detect light output in a hemispheric fashion at all polar and azimuthal angles simultaneously. After detection, a cross section of transmission (e.g., brightness) readings were taken in a direction orthogonal to the direction of the louvers (denoted as a 0 ^ orientation angle), unless indicated otherwise. Relative transmission (i.e., brightness of visible light) is defined as the percentage of on- axis luminance, at a certain viewing angle, between a reading with film and a reading without the film. The Lambertian light source consisted of diffuse transmission from a light box having the baseline luminance profile depicted in FIG.6 of WO 2019 / 118685 A1 (Schmidt et al.). The light box was a six-sided hollow cube measuring approximately 12.5 cm x 12.5 cm c 11.5 cm (L x W x H) made from diffuse polytetrafluoroethylene (PTFE) plates of approximately 6 millimeters (mm) thickness. One face of the box was chosen as the sample surface. The hollow light box had a diffuse reflectance of approximately 0.83 measured at the sample surface (e.g., approximately 83%, averaged over the 400-700 nm wavelength range). During testing, the box was illuminated from within through an approximately 1 cm circular hole in the bottom of the box (opposite the sample surface, with the light directed toward the sample surface from inside). The illumination was provided using a stabilized broadband incandescent light source attached to a fiber-optic bundle used to direct the light (Fostec DCR-II with a 1 cm diameter fiber bundle extension from Schott-Fostec LLC, Marlborough, MA and Auburn, NY). CE1 No Etch Stop Step 1: A microstructured film was prepared as described in “Method for Cast-and-Cure Microreplication to Make Clear Channel Film.” Step 2: The microstructured film was coated with a light absorbing LbL coating as described in “Method to Coat a Light Absorbing Cover Layer - Continuous.” Step 3: The light absorbing layer was etched as described in “Method to Selectively Remove the Light Absorbing Cover Layer.” (See FIG.10, SEM image of CE1 after Step #3). Step 4: The structured film of Step 3 was backfilled as described in “Method to Backfill.” EX 1 LbL Etch Stop – (PDAC / SiO2-5nm)6 Step 1: A microstructured film was prepared as described in “Method for Cast-and-Cure Microreplication to Make Clear Channel Film.” Step 2: A layer-by-layer etch stop was applied on the microstructured film as described in “Method to Coat a Layer-by-Layer Etch Stop (Light Transmissive Layer) – Continuous” using a PDAC coating solution as the Cation and SiO2-5 nm coating solution as the Anion.” Step 3: The microstructured film was coated with a light absorbing LbL coating as described in “Method to Coat a Light Absorbing Cover Layer - Continuous.” Step 4: The light absorbing layer was etched as described in “Method to Selectively Remove the Light Absorbing Cover Layer.” (See FIG.11, SEM image of EX1 after Step #4). Step 5: The structured film of Step 4 was backfilled as described in “Method to Backfill.” EX 2 LbL Etch Stop – (PDAC / SiO2-44nm)6 Step 1: A microstructured film was prepared as described in “Method for Cast-and-Cure Microreplication to Make Clear Channel Film.” Step 2: A layer-by-layer etch stop was applied on the microstructured film as described in “Method to Coat a Layer-by-Layer Etch Stop (Light Transmissive Layer) – Continuous” using a PDAC coating solution as the Cation and SiO2-44 nm coating solution as the Anion.” Step 3: The microstructured film was coated with a light absorbing LbL coating as described in “Method to Coat a Light Absorbing Cover Layer - Continuous.” Step 4: The light absorbing layer was etched as described in “Method to Selectively Remove the Light Absorbing Cover Layer.” (See FIG.12, SEM image of EX2 after Step #4). Step 5: The structured film of Step 4 was backfilled as described in “Method to Backfill.” EX 3 LbL Etch Stop – (PDAC / TiO2)6 Step 1: A microstructured film was prepared as described in “Method for Cast-and-Cure Microreplication to Make Clear Channel Film.” Step 2: A layer-by-layer etch stop was applied on the microstructured film as described in “Method to Coat a Layer-by-Layer Etch Stop (Light Transmissive Layer) – Continuous” using a PDAC coating solution as the Cation and TiO2coating solution as the Anion” Step 3: The microstructured film was coated with a light absorbing LbL coating as described in “Method to Coat a Light Absorbing Cover Layer - Continuous.” Step 4: The light absorbing layer was etched as described in “Method to Selectively Remove the Light Absorbing Cover Layer.” (See FIG.13, SEM image of EX3 after Step #4). Step 5: The structured film of Step 4 was backfilled as described in “Method to Backfill.” EX 4 LbL Etch Stop – (PEI / VMT)6 Step 1: A microstructured film was prepared as described in “Method for Cast-and-Cure Microreplication to Make Clear Channel Film.” Step 2: A layer-by-layer etch stop was applied on the microstructured film as described in “Method to Coat a Layer-by-Layer Etch Stop (Light Transmissive Layer) – Batch” using a PEI coating solution as the Cation and VMT coating solution as the Anion.” Step 3: The microstructured film was coated with a light absorbing LbL coating as described in “Method to Coat a Light Absorbing Cover Layer - Batch.” Step 4: The light absorbing layer was etched as described in “Method to Selectively Remove the Light Absorbing Cover Layer.” (See FIG.14, SEM image of EX4 after Step #4). For Comparative Example 1 (in Step #3 of CE1) and for some of the Examples above (in Step #4 in the corresponding example), %T was measured versus etch time for intermediate samples collected during Step 4. That data plot is shown in Figure 15 and reveals that the etch stop unexpectedly results in a reduced time to “full etch”. This data is also summarized in Tables 2 and 3 herein. Time to “full etch” corresponds to the etch time at which %T reaches a plateau maximum value. We define time to “full etch” as time to reach 95% of the %T value at the conclusion of the etching. Without wishing to be bound by theory, in the absence of the etch stop, it is necessary to effectively over-etch the sample to maximize %T due to differing etch rates of the carbon black particles in the light-absorbing cover layer and the underlying polymer resin. In addition, there is a notably shaper transition to the fully etched plateau for the Examples compared to Comparative Example 1. Table 2: %T vs. etch time for CE1 and EX1-EX3. %TEtch Time CE1 (s) CE1 (replicate) EX1 EX2 EX3 150 35.8 33.8 28.0 35.9 29.5 160 39.3 35.7 32.8 39.5 34.1 170 42.6 37.3 39.2 46.0 38.8 180 46.6 41.5 46.1 53.2 43.9 190 50.1 46.3 54.0 59.4 48.8 200 56.0 50.5 62.4 66.4 54.9 210 61.4 56.9 69.1 74.7 64.4 220 65.0 60.8 75.2 78.0 69.1 230 67.7 63.2 78.8 82.1 73.4 240 71.0 67.4 81.6 85.4 75.1 250 73.0 70.3 84.5 86.8 76.1 260 76.6 74.3 85.7 87.7 76.3 270 78.6 77.5 86.2 88.1 76.9 280 80.5 79.2 86.6 88.3 76.9 290 81.8 80.4 86.8 88.3 77.0 300 82.5 81.4 86.8 88.4 77.1 310 82.7 82.1 86.8 88.3 77.0 320 83.6 82.9 86.9 88.4 77.1 330 84.0 83.7 86.8 88.4 77.3 340 84.4 84.1 86.9 88.3 77.6 350 84.7 84.4 86.9 88.2 77.5 360 84.9 84.6 86.8 88.3 77.5 370 85.2 84.1 86.9 88.2 77.4 380 85.0 85.0 86.8 88.1 76.1 390 85.4 84.9 86.7 88.1 77.2 400 85.0 84.9 86.8 87.8 77.3 410 85.1 85.0 87.0 87.8 76.9 420 85.0 84.9 86.9 87.9 77.4 430 85.2 85.0 86.7 87.8 77.2 440 84.8 85.1 86.9 87.4 77.3 Table 3: Time to full etch for CE1 and EX1-EX3. Time to Full Etch Example (s) CE1 280.5 CE1 (replicate) 294.5 EX1 243.3 EX2 232.8 EX3 230.0 The cross-sectional SEM images show distinct differences between the Comparative Example and the Examples. In the Comparative Example, significant surface roughness is generated on the horizontal surfaces where hair-like projections can be seen in the image (see, e.g., FIG.10). In addition, at the tops of the ridges (e.g., the substantially planar tops 20 of FIG.1A), the light absorbing cover layer extends beyond the level of the top horizontal surface of the microstructured film. At the bottoms of the valleys (see, e.g., landings 25 in grooves 28 of FIG.1A), the light absorbing cover layer does not extend to the level of the bottom horizontal surface of the microstructured film. This can be explained by the etching of the polymer resin on both the the top and bottom horizontal surfaces. In the Examples, on the other hand, at the tops of the ridges, the light absorbing cover layer does not reach the same level as the horizontal surface of the microstructured film. The etch stop (i.e., light transmissive layer 40, e.g., see FIG.1A) on the top horizontal surface has a lower etch rate than the light absorbing cover layer, such that the cover layer is etched below the level of the top surface. At the bottom of the valleys, the light absorbing cover layer does approximately reach the same level of the etch stop (i.e., the light transmissive layer). Table 4: Thickness, refractive index, wt% inorganic particles, porosity, and vol% inorganic particles in the LbL etch stops (i.e., “light transmissive layers”) of EX1-EX3. Example Etch Stop Etch Stop Wt% Porosity Vol% Thickness Refractive Inorganic (vol%) Inorganic (nm) Index at 633 Particle Particle nm EX1 56 ± 10 1.35 80.2 19.2 50.0 EX2 120 ± 14 1.27 93.3 40.1 47.2 EX3 40 ± 5 1.93* 81.8 8.6 56.3 * This value obtained by measuring a coating with 10 bilayers. After the backfill step of CE1 (i.e., Step 4) and EX1 (i.e., Step 5), the luminance profile was measured using the “Method for Measuring the Luminance Profile from a Diffuse Light Source”. Data for CE1 and EX1 are shown in Table 5 below. Both have desirably high (>85% relative transmission) on-axis luminance and similar off-axis (30° and 35-80° relative transmission) luminance. Table 5: Luminance profile from a diffuse light source for CE1 and EX1. Example On-axis (0°) Relative Relative relative transmission transmission, transmission at 30° averaged from 35-80° CE1 86.3 10.4 1.1 EX1 88.4 11.8 1.0 Terms such as “about” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “about” as applied to quantities expressing feature sizes, amounts, and physical properties is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “about” will be understood to mean within 10 percent of the specified value. A quantity given as about a specified value can be precisely the specified value. For example, if it is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, a quantity having a value of about 1, means that the quantity has a value between 0.9 and 1.1, and that the value could be 1. Terms such as “substantially” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “substantially equal” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially equal” will mean about equal where about is as described above. If the use of “substantially parallel” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially parallel” will mean within 30 degrees of parallel. Directions or surfaces described as substantially parallel to one another may, in some embodiments, be within 20 degrees, or within 10 degrees of parallel, or may be parallel or nominally parallel. If the use of “substantially aligned” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially aligned” will mean aligned to within 20% of a width of the objects being aligned. Objects described as substantially aligned may, in some embodiments, be aligned to within 10% or to within 5% of a width of the objects being aligned. All references, patents, and patent applications referenced in the foregoing are hereby incorporated herein by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control. Descriptions for elements in figures should be understood to apply equally to corresponding elements in other figures, unless indicated otherwise. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

What is claimed:

1. A light control film comprising a structured first major surface opposite a second major surface, the structured first major surface comprising a plurality of structures extending in a thickness direction of the light control film separated by one or more grooves, each structure comprising one or more side surfaces, each groove having one or more substantially planar landings joining the corresponding structures; each of the one or more side surfaces making an angle with an adjacent landing of the one or more landings, the angle being greater than about 60 degrees; at least 80% of the one or more side surfaces and the one or more landings coated with a first light transmissive layer having a first average thickness of greater than about 0.005 microns and comprising a plurality of first inorganic particles at a volume loading of greater than about 5%; at least 70% of the first light transmissive layer on each of the one or more side surfaces and at most 30% of the first light transmissive layer on the one or more landings coated with a cover layer, the first light transmissive layer coated on the one or more side surfaces having an arithmetic average surface roughness Ra2, the first light transmissive layer coated on the one or more landings having an arithmetic average surface roughness Ra1, wherein Ra1 > Ra2.

2. The light control film of claim 1, wherein the one or more side surfaces comprises a first side surface and a second side surface connected by a substantially planar top surface, the substantially planar top surface substantially parallel to the one or more landings.

3. The light control film of claim 2, wherein at most 30% of the first light transmissive layer on the planar top surface is coated with a cover layer, and the planar top surface has an arithmetic average surface roughness substantially the same as the first light transmissive layer coated on the one or more landings.

4. The light control film of claim 1, wherein the one or more side surfaces comprises a first side surface and a second side surface, the first side surface and the second side surface meeting at a peak. 5, The light control film of claim 1, wherein the plurality of structures comprises linear structures extending substantially across a width direction of the light control film and arranged along an orthogonal length direction of the light control film, each linear structure separated from each adjacent linear structure by a groove.

6. The light control film of claim 1, wherein the plurality of structures comprises a plurality of posts arranged along a width direction and an orthogonal length direction of the light control film, atleast a portion of the posts in the plurality of posts substantially surrounded by the one or more landings.

7. The light control film of claim 1, wherein Ra2 is greater than zero.

8. The light control film of claim 1, wherein the one or more side surfaces have an arithmetic surface roughness within about 10% of Ra2.

9. The light control film of claim 1, wherein the one or more landings have an arithmetic surface roughness less than about Ra1 / 10.

10. The light control film of claim 1, further comprising a second light transmissive layer comprising the first inorganic particles disposed on at least a portion of the cover layer, the second light transmissive layer having a second average thickness of less than about 20 nm.

11. The light control film of claim 1, wherein the cover layer is light absorbing.

12. The light control film of claim 1, wherein the cover layer has an average thickness of greater than about 0.05 microns.

13. The light control film of claim 1, further comprising a planarizing overcoat covering, and substantially planarizing, the structured first major surface.

14. The light control film of claim 13, wherein a refractive index of the planarizing overcoat is different from a refractive index of the plurality of structures by greater than about 0.

07.

15. The light control film of claim 1, wherein the first inorganic particles comprise one or more of silicon dioxide, titanium dioxide, zirconium dioxide, aluminum oxide, and clay platelets.

16. A display system comprising the light control film of claim 1 and a display configured to form an image to a viewer, the light control film disposed between the viewer and the display.

17. A light control film comprising:a light transmissive body comprising a plurality of structures extending in a thickness direction of the light control film separated by one or more grooves, each structure comprising one or more side surfaces, each groove having one or more substantially planar landings joining the corresponding structures; a first light transmissive layer having a first average thickness of greater than about 0.005 microns and coated on at least 80% of the plurality of structures and the one or more landings, the light transmissive layer comprising a plurality of first inorganic particles comprising a first inorganic material; a light absorbing layer having an average thickness of greater than about 0.05 microns and coated on at least 70% of the light transmissive layer on the one or more side surfaces and on at most 30% of the light transmissive layer on each of the one or more landings; and a planarizing overcoat covering the light absorbing layer and substantially planarizing the structured first major surface, wherein for each of at least some of one or more side surfaces and the one or more landings, a second light transmissive layer is disposed between the planarizing overcoat and the light absorbing layer, the second light transmissive layer comprising the first inorganic material and having a second average thickness that is less than about 20 nm.

18. The light control film of claim 17, wherein a refractive index of the planarizing overcoat is different from a refractive index of a material comprising the first major surface by greater than about 0.

07.

19. The light control film of claim 17, wherein the light control film is bonded to an adhesive.

20. The light control film of claim 19, wherein the adhesive has a haze value of at least 10%.

Images