Device comprising a nanotube and nano-objects encapsulated in the nanotube, method for synthesising such a device, and use of such a device

Abstract

The invention relates to a device (1) comprising: - a nanotube (2) extending longitudinally; - nano-objects of a first type (3) encapsulated in the nanotube; and - nano-objects of a second type (4) encapsulated in the nanotube, the nano-objects of the first type being absorbers and / or emitters of photons in a wavelength range, the nano-objects of the second type being transparent in said wavelength range, the nano-objects of the first type and the nano-objects of the second type being encapsulated longitudinally one after the other in the nanotube, at least one nano-object of the second type being encapsulated in the nanotube between two nano-objects of the first type.

Description

DESCRIPTION TITLE OF THE INVENTION: DEVICE COMPRISING A NANOTUBE AND NANO-OBJECTS ENCAPSULATED IN THE NANOTUBE, METHOD FOR SYNTHESIZING SUCH A DEVICE AND USE OF SUCH A DEVICE TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates generally to the field of nanomaterials.

[0002] It relates more specifically to a device comprising a nanotube and nano-objects encapsulated in the nanotube.

[0003] The invention finds a particularly advantageous application in the realization of networks of coupled light emitters, to generate collective states of the super-radiant or super-fluorescent type. STATE OF THE ART

[0004] Current optical imaging methods widely use fluorescence probes to provide optical contrast. Fluorescence emission is typically achieved by fluorophores, which are molecules capable of spontaneously emitting light. Fluorescence is also used in numerous applications such as lighting, analytical chemistry, forensics, civil security, and data storage. Fluorescence labeling, on the other hand, is more specifically used in applications such as biological imaging, medical diagnostics, automated DNA sequencing, and immunological assays.

[0005] The encapsulation of fluorophores in crystalline nanomaterials has been studied with the aim of preventing photobleaching of these fluorophores, i.e., their loss of fluorescence. Advantageously, the encapsulation of fluorophores in inorganic nanotubes (e.g., ZnO, MgO, and BN nanotubes) does not extinguish luminescence and effectively protects the fluorophores from photobleaching. For example, a fluorescent probe consisting of a boron nitride nanotube encapsulating a plurality of fluorescent molecules in the infrared range is known from patent US11982676.

[0006] However, the coupling strength and dipolar coherence of these fluorophores are not tunable. Thus, although the fluorophores are concentrated in a nanotube, the high number of fluorophores is not used to its full potential.

[0007] Therefore, the need arose to better control the coupling between fluorophores and the emission of photons by arrays of emitters encapsulated in a nanotube. PRESENTATION OF THE INVENTION

[0008] In this context, the present invention proposes a device comprising: - a nanotube extending longitudinally; - nano-objects of a first type encapsulated in the nanotube; and - nano-objects of a second type encapsulated in the nanotube, the nano-objects of the first type being absorbers and / or emitters of photons in a range of wavelengths, the nano-objects of the second type being transparent in said range of wavelengths, the nano-objects of the first type and the nano-objects of the second type being encapsulated longitudinally one after the other in the nanotube, at least one nano-object of the second type is encapsulated in the nanotube between two nano-objects of the first type.

[0009] Thus, thanks to the size of the second type of nano-objects, the first type of nano-objects can be spaced more or less closely within the nanotube. Modulating the distance between the first type of nano-objects allows for modulation of the coupling strength. This notably enables them to emit photons coherently. Indeed, the first type of nano-objects are sufficiently spaced, typically more than 0.4 nm (van der Waals distance), within the nanotube to prevent them from aggregating. Slightly spacing the emitters avoids chemical interactions between them and prevents their aggregation (of the H or J type), which would counteract the superradiance effect (see below). The separation distance is, for example, 5–100 nm, up to the wavelength, approximately 600 nm.

[0010] Instead of acting as several independent emitters, the nano-objects of the first type act in concert as a super-emitter, emitting several photons in a synchronized manner. The device according to the invention can then be described as "super-radiant" or "super-fluorescent".

[0011] Advantageously, the device according to the invention makes it possible to reduce by in a controlled manner the fluorescence lifetime of the first type of nano-objects, compared to the lifetime of a single first type of nano-object (typically reducing it from nanoseconds to a few tens of picoseconds). While maintaining or increasing the intensity of the photon emitted by the system.

[0012] Indeed, controlling the distance between the first type of nano-objects, i.e. in practice controlling the number of second type nano-objects interposed between the first type of nano-objects, allows adjusting the strength of the dipolar coupling between the first type of nano-objects, therefore the number of first type nano-objects coupled, and thus the state of super-radiance or superfluorescence.

[0013] It is therefore possible to create fluorescent devices with a unique optical signature, for example encoded by a fluorescence wavelength - fluorescence lifetime pair or by a combination of fluorescence lifetimes.

[0014] Remarkably, this allows, for example, the selection of the most suitable nano-objects of the first type for a given application, for example because they are absorbers and / or emitters of photons over a wavelength range appropriate to a given environment, and then the adjustment of the fluorescence lifetime of the device.

[0015] Other advantageous and non-limiting features of the device according to the invention, taken individually or in all technically possible combinations, are as follows: - the nanotube has one or more walls, and is dielectric or semiconducting; - said two nano-objects of the first type are longitudinally separated only by said at least one nano-object of the second type; - between one and six nano-objects of the second type are encapsulated in the nanotube between said two nano-objects of the first type; - the distance between said two nano-objects of the first type is between 0.4 nm and 500 nm, or between 1 nm and 1000 nm, or between 500 nm and 1700 nm; - the nanotube has a width, transverse to its longitudinal extension, which is between 0.5 and 2 times the length of nano-objects of the first type; - the nanotube is a boron nitride nanotube; - nano-objects of the first type and nano-objects of the second type are selected from the group including: molecules, quantum dots, nanocrystals; - nano-objects of the first type have a band gap whose energy is lower than the band gap energy of nano-objects of the second type and the band gap energy of the nanotube; - the nano-objects of the first type are a-sexithiophen molecules and in which the nano-objects of the second type are anthracene molecules; - the nano-objects of the first type are DPP2 molecules, and in which the nano-objects of the second type are α-sexithiophene molecules; and - Nano-objects of the second type are emitters and / or absorbers of photons in a second range of wavelengths distinct from the first range of wavelengths.

[0016] The invention also proposes a method for synthesizing a device as described above, comprising the following steps: - preparation of a solution comprising the nanotube, nano-objects of the first type and nano-objects of the second type, said nano-objects being dispersed in the solution, - encapsulation of nano-objects of the first type and nano-objects of the second type in the nanotube.

[0017] Advantageously, the manufacturing method for the device is simple and inexpensive.

[0018] Remarkably, the spacing between the first type of nano-objects confined in the nanotube is statistically controlled by the relative concentration of the different components in the preparation of the solution for encapsulation.

[0019] The process is preferably used for the synthesis of a device in which the nano-objects of the first type are α-sexithiophen molecules and in which the nano-objects of the second type are anthracene molecules, or in which the nano-objects of the first type are DPP2 molecules and in which the nano-objects of the second type are α-sexithiophen molecules.

[0020] Other advantageous and non-limiting features of the process according to the invention, taken individually or in all technically possible combinations, are as follows: - a ratio, in said solution, between the concentration of nano-objects of the first type and the concentration of nano-objects of the second type is determined so as to obtain a given average spacing between the nano-objects of the first type; and - a ratio, in said solution, between the concentration of nano-objects of the first type and the concentration of nano-objects of the second type is between 1 / 250 and 1 / 500.

[0021] The invention finally proposes the use of a device such as described above as a probe for bio-imaging, as a single photon source, as a super radiant device, or for the formation of a fluorescent coating whose fluorescence duration is predetermined.

[0022] Of course, the different features, variants and embodiments of the invention can be combined with each other in various ways as long as they are not incompatible or mutually exclusive. DETAILED DESCRIPTION OF THE INVENTION

[0023] The description that follows, with regard to the attached drawings, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be carried out.

[0024] Regarding the attached drawings:

[0025] Figure 1 is a three-dimensional schematic representation of a section of a device according to the invention.

[0026] Figure 2 is a schematic representation of a solution (on the left) and devices according to the invention (A, B and C, on the right) made from this solution,

[0027] Figure 3 is a graphical representation showing the average spacing (E, in nanometers) between nano-objects of a first type within devices according to the invention as a function of the ratio of concentrations used for the manufacture of these devices,

[0028] Figure 4 is a reproduction of a confocal fluorescence image showing a spatial distribution of the light intensity emitted by nano-objects of a first type,

[0029] Figure 5 is a graphical representation showing the fluorescence lifetime (T, in nanoseconds) of devices according to the invention as a function of the average spacing (E, in nanometers) between nano-objects of a first type within these devices,

[0030] Figure 6 is a graphical representation showing the luminous intensity emitted (I, dimensionless) by devices according to the invention as a function of the fluorescence lifetime of these devices, and

[0031] Figure 7 is a schematic perspective and transparency representation of a portion of a film comprising a plurality of devices according to the invention.

[0032] A device 1 according to the invention is shown in Figure 1. Here, "device" refers to a very small object, typically less than one millimeter in size. In the following description, device 1 is described in the context of its use as a super-radiant fluorescent probe, for example, for bioimaging. Of course, many other uses for device 1 are possible. Various functionalities of device 1 can be obtained by modifying the nature of the encapsulated nano-objects while remaining within the scope of the invention.

[0033] As shown in Figure 1, device 1 comprises: - a nanotube 2 extending longitudinally; - nano-objects of a first type 3, hereafter called first nano-objects 3, encapsulated in the nanotube 2; and - nano-objects of a second type 4, subsequently called second nano-objects 4, encapsulated in nanotube 2.

[0034] Nanotube 2 is described here as a hollow, cylindrical crystalline structure. It extends lengthwise around a longitudinal axis A1. For example, the length of nanotube 2 ranges from 0.1 pm to 10 pm. Nanotube 2 extends longitudinally in the sense that its length is significantly greater than its transverse dimensions perpendicular to the longitudinal axis A1. The term "nanotube" here refers to the fact that the transverse dimensions of nanotube 2 are on the nanometer scale, meaning smaller than one micrometer. For example, nanotube 2 has an internal width (measured perpendicular to the longitudinal axis A1) ranging from 1 nm to 20 nm. As shown in Figure 1, nanotube 2 is, more specifically, approximately cylindrical in its orientation. Its cross-section perpendicular to the longitudinal axis A1 is thus generally circular.

[0035] As shown in Figure 1, the first 3 nano-objects are aligned with the longitudinal axis A1 of the nanotube 2, which means that the direction of their most The large dimension is aligned with the longitudinal axis A1 of nanotube 2. The first nano-objects 3 are therefore aligned with each other. This alignment naturally results from the encapsulation of the first nano-objects 3.

[0036] The nanotube 2 preferably has a width, i.e., a diameter, that is between 0.5 and 2 times the length of the first nano-objects 3. Here, the "length" of the first nano-objects 3 refers to their longest dimension. Advantageously, this particular width of the nanotube 2 promotes the alignment of the first nano-objects 3 along the longitudinal axis A1 of the nanotube 2, which increases their alignment with each other and thus the strength of their dipolar coupling. They therefore emit light more coherently. The efficiency of the dipolar coupling is approximately proportional to the cosine of the angle defined between the longitudinal axis A1 of the nanotube 2 and the direction of the length of the first nano-objects 3.

[0037] As shown in Figure 1, nanotube 2 has a single wall. However, it can have several walls extending concentrically around the longitudinal axis A1, for example from 1 to 5 walls.

[0038] Nanotube 2 is fabricated in a dielectric or semiconductor material, for example, a wide-bandgap semiconductor (the interval between the valence and conduction bands) with an energy greater than 5 eV. In this case, nanotube 2 is made of boron nitride. Generally, nanotube 2 is fabricated in a material with a bandgap higher than that of the first nano-objects, nanotube 3.

[0039] The fact that the first nano-objects 3 are "of a first type" means, in particular, that the first nano-objects 3 are all identical. Similarly, the fact that the second nano-objects 4 are "of a second type" means, in particular, that the second nano-objects 4 are all identical. Here, this means that the first nano-objects 3 all have the same chemical composition and preferably the same conformation (they therefore exhibit the same molecular structure). Likewise, the second nano-objects 4 all have the same chemical composition and preferably the same conformation.

[0040] The first nano-objects 3 and the second nano-objects 4 are encapsulated in the nanotube 2, that is, housed inside the nanotube 2. As shown in Figure 1, the first nano-objects 3 and the second nano-objects 4 are positioned along the longitudinal axis A1. The nano-objects 3 and 4 encapsulated in the nanotube 2 are held substantially along the longitudinal axis A1, that is to say at an equidistance from the wall of the nanotube 2, by van der Waals forces.

[0041] By "nano-objects," we mean here that the largest dimension of the first nano-objects 3 and the second nano-objects 4 (here their length, measured along the longitudinal axis A1 in Figure 1) is on the nanometer scale, that is, smaller than a micrometer. For example, the first nano-objects 3 and the second nano-objects 4 have a length between 1 nm and 4 nm.

[0042] As shown in Figure 1, the first nano-objects 3 and the second nano-objects 4 are encapsulated longitudinally one after the other in the nanotube 2. In other words, the first nano-objects 3 and the second nano-objects 4 are positioned side by side along the longitudinal axis A1 of the nanotube 2, as opposed to a side-by-side positioning in the width of the nanotube 2. Thus, a cross-section of the nanotube 2 (perpendicular to the longitudinal axis A1) comprises at most one nano-object: a first nano-object 3 or a second nano-object 4.

[0043] As shown in Figure 1, at least one second nano-object 4 is encapsulated in the nanotube 2 between two first nano-objects 3. Said at least one second nano-object 4 is therefore interposed between said two first nano-objects 3. Said two first nano-objects 3 considered are said to be "successive", that is to say without any other first nano-object interposed between them.

[0044] In other words, there are two first nano-objects 3 in nanotube 2 separated by a second nano-object 4. Statistically, in nanotube 2 all the first nano-objects 3 are separated from each other by second nano-objects 4. Here, although this is statistically very improbable given the concentration ratios described later, it is not excluded that two first nano-objects 3 could follow one another in nanotube 2.

[0045] Put another way, the first nano-objects 3 and the second nano-objects 4 are encapsulated longitudinally, one after the other, within the nanotube 2 in an alternating pattern. This alternation introduces an element of randomness, as the sequence between the first nano-objects 3 and the second nano-objects 4 is not necessarily regular. Thus, as Figure 2 clearly shows, two first nano-objects 3 can be separated by one, two, or three second nano-objects within the same nanotube 2. Preferably, two successive first nano-objects 4 are separated longitudinally. by one to six second nano-objects 4.

[0046] This spacing between the first nano-objects 3 allows here to obtain a super-radiant device 1 in the sense that the first nano-objects 3 are coupled to each other and emit light in a coherent way, that is to say in a temporally synchronized way.

[0047] Here, device 1 is specifically composed of nanotube 2, the first two nano-objects 3, and the second two nano-objects 4, meaning that it comprises only these elements. The first two nano-objects 3 are thus separated longitudinally only by one or more second nano-objects 4.

[0048] The distance between the first two nano-objects 3 is preferably between 0.4 nm and 500 nm in order to modulate and maximize their dipolar coupling and thus their superradiance state. Indeed, below 0.4 nm, the first two nano-objects 3 tend to aggregate and share electrons, while above 500 nm they become too far apart, which in both cases reduces their dipolar coupling. However, the distance between the first two nano-objects 3 can be between 1 nm and 1000 nm, or between 500 nm and 1700 nm, which still provides them with satisfactory dipolar coupling.

[0049] The first nano-objects 3 exhibit optical properties different from those of the second nano-objects 4. In the example shown in figures 1 to 6, the first nano-objects 3 are generally light emitters while the second nano-objects 4 are spacers allowing adjustment of the distance between the first nano-objects 3.

[0050] The first nano-objects 3 are more specifically absorbers and emitters of photons within a certain wavelength range, that is, within a given wavelength interval or spectral range. This wavelength range is an intrinsic characteristic of the first nano-objects 3, and it depends in particular on their molecular structure. For example, "absorbers" are defined as first nano-objects 3 exhibiting an absorbance greater than 10% for all wavelengths within this wavelength range. Absorption allows the first nano-objects 3 to be excited by a beam of light. In response to this excitation, the first nano-objects 3 emit photons spontaneously after a variable delay. The first nano-objects 3 emit photons within this range of wavelengths in the sense that the emitted photons have a wavelength very close to that of excitation (fluorescence phenomenon). Advantageously, since device 1 is super-radiant, the spontaneous emissions of the first nano-objects 3 of device 1 are synchronous.

[0051] In the example shown in Figure 1, the first nano-objects 3 and the second nano-objects 4 are molecules. Here, the first nano-objects 3 are more specifically fluorescent molecules (i.e., fluorophores, also commonly called dyes) and are thus absorbers and emitters of photons in the aforementioned wavelength range. This wavelength range is, for example, in the infrared region, extending from 0.7 pm to 5 pm, or in the near-infrared region, extending from 0.7 pm to 1 pm.

[0052] The second nano-objects 4 are specifically transparent within the aforementioned wavelength range, meaning they absorb little or no light within that range. For example, they exhibit an absorbance of less than 1% for wavelengths within that range. Preferably, they absorb no photons at all within that wavelength range. In other words, the absorption bands of the first nano-objects 3 and the second nano-objects 4 are preferably disjoint.

[0053] The second nano-objects 4 can be optically neutral, meaning here that they do not emit light. They therefore emit no photons in the specified wavelength range. In the context of device 1 as a fluorescent probe, this specifically means that the second nano-objects 4 are not fluorescent.

[0054] The second nano-objects 4 can also be absorbers and / or emitters of light in a different wavelength range, distinct from the aforementioned wavelength range. In other words, the second nano-objects 4 are then fluorescent at wavelengths distinct from those of the first nano-objects 3. Thus, advantageously, the second nano-objects 4 act as spacers for the first nano-objects 3, and, conversely, the first nano-objects 3 act as spacers for the second nano-objects 4.

[0055] As an example, the first nano-objects 3 are a-sexithiophene molecules and the second nano-objects 4 are anthracene molecules whose absorption and emission wavelength ranges are respectively from 300 nm to 400 nm and from 400 to 500 nm. α-sexithiophene molecules have a band gap of 3 eV and are fluorescent at visible wavelengths, the said wavelength range extending, for example, from 450 nm to 550 nm for absorption and from 580 nm to 780 nm for emission.

[0056] As another example, the first nano-objects 3 are DPP2 molecules (3,6-bis[2,2']bithiophenyl-5-yl-2,5-di-n-oc-tylpyrrolo[3,4-c]pyrrole-1,4-dione) with an absorption range between 600 nm and 700 nm and an emission range between 700 nm and 800 nm. The second nano-objects 4 are anthracene molecules.

[0057] Preferably, the first nano-objects 3 have a band gap energy lower than the band gap energy of the second nano-objects 4. Thus, the photons emitted by the first nano-objects 3 cannot be absorbed by the second nano-objects 4. Similarly, the band gap energy of the first nano-objects 3 is preferably lower than that of the band gap of the nanotube 2.

[0058] We now describe a synthesis process, that is to say a manufacturing process, of device 1. This process mainly includes the encapsulation of the first nano-objects 3 and the second nano-objects 4 in the nanotube 2.

[0059] As illustrated in Figure 2, this process includes a first step of preparing a solution 5 comprising the nanotube 2, first nano-objects 3 and second nano-objects 4. For this, the nanotube 2, the first nano-objects 3 and the second nano-objects 4 are solubilized in a solvent 6. The nanotube 2, the first nano-objects 3 and the second nano-objects 4 are thus dispersed in the solution 5.

[0060] In practice, solution 5 comprises a plurality of nanotubes 2. The process thus makes it possible to manufacture a plurality of devices 1 simultaneously.

[0061] The process then includes a second step of encapsulating the nano-objects 3, 4. This second step involves heating the solution 5. Solution 5 is heated in a reflux setup (not shown). For example, solution 5 is heated for a period ranging from 2 minutes to 48 hours at a temperature above 80°C.

[0062] During this second stage, the first nano-objects 3 and the second nano-objects 4 enter and lodge themselves in the nanotubes 2. The devices 1 are thus formed in solution 5.

[0063] The process may also include a third step for isolating the devices 1. This isolation step may involve, for example, a series of washes on a 0.22 µm PTFE membrane and rinsing in a clean solvent to remove the majority of the unencapsulated nano-objects 3, 4. This isolation step then involves recovering the devices 1 from a 0.22 µm PTFE membrane and dispersing them in a new solvent, depending on the environment required for future applications or characterizations.

[0064] Advantageously, as shown in Figure 3, the spacing between the first nano-objects depends on the concentrations (i.e., the quantities) of nano-objects 3, 4 in the solution 5.

[0065] In Figure 3, each point represents the average spacing (E) of the first nano-objects 3 within a device 1. In the example in Figure 3, the first nano-objects 3 are α-sexithiophene molecules, the second nano-objects 4 are anthracene molecules and the nanotubes 2 are boron nitride nanotubes.

[0066] In Figure 3, the devices 1 on the right at abscissa 1:250 were prepared with a concentration ratio in solution 5 between the first nano-objects 3 and the second nano-objects 4 of 1:250 (1 for 250).

[0067] For example, they were prepared according to the following protocol.

[0068] To fabricate nanotubes 2, boron nitride powder is annealed at 800°C in air for 2 hours, with the nanotubes already formed within the powder. This step pyrolyzes any organic contaminants on the surface or within the nanotubes 2 and oxidizes boron impurities. After annealing, the powder is dispersed in DMF using a cup sonicator for 2 hours until complete dispersion is achieved. This step mechanically breaks open the nanotubes 2. The solution is then centrifuged at 12,000 g for 10 minutes, and the upper half of the centrifuged container is collected. This step facilitates the recovery of individual, small-diameter nanotubes 2 and removes two-dimensional hexagonal boron nitride flakes and boron nitride onions suspended in the DMF (dimethylformamide).Optionally, the solution containing nanotubes 2 is filtered with a membrane (0.22 µm PTFE) and then dispersed in a new solvent using an ultrasonic bath for 20 mins. This filtration. allows, for example, changing the solvent 6 in order to ensure compatibility between the solution 5 and the nano-objects 3, 4 to be encapsulated.

[0069] To prepare solution 5, 15.95 mL of toluene is introduced into a 50 mL flask 7 (see Figure 2). 100 pL of 5 x 10⁻⁶ mol α-sexithiophene L' 1 in a solution of toluene and 9 mL of anthracene at 1.4 x 10⁻⁵ mol 1 In a toluene solution, the nanotubes are added to flask 7 and then mixed with a magnetic stir bar for 1 hour. The purified nanotubes are added to solution 5. Encapsulation is carried out for 48 hours at 85°C. The devices in solution are then rinsed and dispersed in a new solvent.

[0070] The devices 1 on the left at abscissa 1:500 were prepared with a concentration ratio in solution 5 between the first nano-objects 3 and the second nano-objects 4 of 1:500 (1 for 500).

[0071] For example, they were prepared according to the following protocol.

[0072] The fabrication of nanotubes 2 is identical to that described above for the ratio 1:250.

[0073] To prepare solution 5, 15.95 mL of toluene is introduced into a 50 mL flask 7 (see Figure 2). 50 pL of α-sexithiophene at 5 x 10⁻⁶ mol L' 1 in a solution of toluene and 9 mL of anthracene at 1.4 x 10⁻⁵ mol 1 In a toluene solution, the nanotubes are added to flask 7 and then mixed with a magnetic stir bar for 1 hour. The purified nanotubes are added to solution 5. Encapsulation is carried out for 48 hours at 85°C. The devices in solution are then rinsed and dispersed in a new solvent.

[0074] The average spacing of the first nano-objects 3 within a device 1 is characterized, for example, by imaging. Figure 4 shows an image of a portion of a device 1 acquired by confocal fluorescence imaging with excitation of α-sexithiophen molecules at a wavelength of 633 nm. Three α-sexithiophen molecules are visible in Figure 4; they are represented by the three bright areas indicative of high intensity. The emission is polarized along the longitudinal axis A1. As shown in Figure 4 (taken in the same plane as Figure 1), the spacing between the α-sexithiophen molecules, i.e., the first nano-objects 4, is on the order of 500 nm.

[0075] As Figure 3 clearly shows, the average spacing of the first nanoobjects 3 within the devices 1 is statistically greater for the ratio 1:500 than for the ratio 1:250.

[0076] Thus, Figure 3 clearly illustrates that the lower the ratio of concentrations in the solution between the first nano-objects 3 and the second nano-objects 4, the more spaced out the first nano-objects 3 are within the devices 4. Indeed, when more second nano-objects 4 are dispersed in the solution 5, more second nano-objects 4 can enter a nanotube 2 between the entries of two successive first nano-objects 3.

[0077] We can therefore determine the concentrations of first nano-objects 3 and second nano-objects 4 so as to obtain a given average spacing between the first nano-objects 3. In other words, the relative concentration of the different nano-objects 3, 4 confined in the nanotube 2 is determined by the relative concentration of the different nano-objects in the solution 5 for encapsulation.

[0078] Concentration is not, however, the only parameter that controls the spacing between the first nano-objects 3. Other parameters also control this spacing. Since the entry of a nano-object 3, 4 into the nanotube 2 is governed by thermodynamics, it depends, for example, on the time the nano-object 3, 4 spends in front of the end of the nanotube 2. Each type of nano-object 3, 4 thus exhibits its own entry dynamics into the nanotube 2, for example, based on its affinity for the nanotube 2. Modifying certain environmental parameters, such as the temperature of the solution 5, allows for changes in the entry dynamics of the first nano-objects 3 and second nano-objects 4 into the nanotube 2, and therefore allows for changes in the spacing of the first nano-objects 3 within the nanotubes 2 (although less significantly than the concentrations).This is illustrated in figure 2 where the same concentration ratio can give several spacings (see devices (A), (B) and (C)).

[0079] Figure 5 illustrates that the spacing between the photon emitters, i.e., here between the first nano-objects 3, modifies the degree of superradiance of device 1. Indeed, as Figure 5 clearly shows, the larger the average spacing between the first nano-objects, the longer the fluorescence lifetime. In comparison, the point corresponding to the average spacing close to zero (labeled P) represents the fluorescence lifetime of a nanotube encapsulating only the first nano-objects, which is much shorter than when there is coupling, as in the superradiant device 1.

[0080] Figure 6 illustrates the corollary of this super-radiance: the longer the lifespan The higher the fluorescence intensity, the lower the emitted intensity. However, the intensity is lower than for a nanotube filled solely with first nano-objects 3.

[0081] The present invention is in no way limited to the embodiment described and represented, but a person skilled in the art will be able to make any variation in accordance with the invention.

[0082] So far, the coupling of emitters has been described within the same nanotube 2. However, it is possible to couple emitters positioned in different nanotubes 2.

[0083] As shown in Figure 7, it is possible, for example, to encapsulate nano-objects 3, 4 in nanotubes 2 aggregated together and forming a film of variable thickness (5 nm to 1 micron). The nanotubes 2 extend approximately parallel to each other, notably due to van der Waals forces.

[0084] As an example, for an anthracene / sexithiophene ratio of 1:250, the lifetime is approximately 1 ns for an individual nanotube 2 and 0.2 ns for the nanotube 2 film. This decrease in lifetime demonstrates a coupling effect between different nanotube 2 emitters within the film.

[0085] Grouping nanotubes in a film advantageously allows emitters to be brought closer together and average spacings below 100 nm to be easily achieved.

[0086] The super-radiance of device 1 can indeed be applied to uses other than fluorescence imaging. Thus, the first nano-objects can be different from fluorescent molecules.

[0087] For example, the first nano-objects may simply be photon absorbers. These early nano-objects are made of semiconductor materials. They may be fluorescent quantum dots or nanocrystals, such as perovskites. Such devices are particularly well-suited for use in photovoltaic cells.

[0088] The first nano-objects can also be only photon emitters over said wavelength range, they are then typically photon absorbers over another distinct wavelength range.

[0089] The device can also include more than two types of nano-objects, for example to obtain more than two emission beams. It can thus, for example understand three different types of emitters, each type of emitter being a spacer for the other two types of emitters.

[0090] The device can also be used as a source of single photons. For this to happen, it is planned that the spacing between the first nano-objects will be large enough (greater than the coherence distance or the excitation wavelength), for example greater than 600 nm or 1000 nm, so that the first nano-objects will be decoupled.

[0091] The device can, for example, be used to create a fluorescent coating with a predetermined fluorescence duration. Such a coating can, for instance, serve as a signature to identify the products to which it is applied.

Claims

DEMANDS

1. Device (1) comprising: - a nanotube (2) extending longitudinally; - nano-objects of a first type (3) encapsulated in the nanotube (2); and - nano-objects of a second type (4) encapsulated in the nanotube (2), the nano-objects of the first type (3) being absorbers and / or emitters of photons in a range of wavelengths, the nano-objects of the second type (4) being transparent in said range of wavelengths, the nano-objects of the first type (3) and the nano-objects of the second type (4) being encapsulated longitudinally one after the other in the nanotube (2), at least one nano-object of the second type (4) is encapsulated in the nanotube (2) between two nano-objects of the first type (3).

2. Device (1) according to claim 1, wherein said two nano-objects of the first type (3) are longitudinally separated only by said at least one nano-object of the second type (4).

3. Device (1) according to claim 1 or 2, wherein between one and six nano-objects of the second type (4) are encapsulated in the nanotube (2) between said two nano-objects of the first type (3).

4. Device (1) according to any one of claims 1 to 3, wherein the distance between said two nano-objects of the first type (3) is between 0.4 nm and 500 nm, or between 1 nm and 1000 nm, or between 500 nm and 1700 nm.

5. Device (1) according to any one of claims 1 to 4, wherein the nanotube (2) has a width, transverse to its longitudinal extension, which is between 0.5 and 2 times a length of the nano-objects of the first type (3).

6. Device (1) according to any one of claims 1 to 5, wherein the nanotube (2) is a boron nitride nanotube (2).

7. Device (1) according to any one of claims 1 to 6, wherein nano-objects of the first type (3) and nano-objects of the second type (4) are selected from the group including: molecules, quantum dots, nanocrystals.

8. Device (1) according to any one of claims 1 to 7, wherein the nano-objects of the first type (3) have a band gap whose energy is lower than the band gap energy of the nano-objects of the second type (4) and the band gap energy of the nanotube (2).

9. Device (1) according to any one of claims 1 to 8, wherein the nano-objects of the first type (3) are a-sexithiophene molecules and wherein the nano-objects of the second type (4) are anthracene molecules.

10. Device (1) according to any one of claims 1 to 8, wherein the nano-objects of the first type (3) are DPP2 molecules and wherein the nano-objects of the second type (4) are a-sexithiophen molecules.

11. Device (1) according to any one of claims 1 to 10, wherein the nano-objects of the second type (4) are emitters and / or absorbers of photons in a second wavelength range distinct from the first wavelength range.

12. A method for synthesizing a device (1) according to any one of claims 1 to 11 comprising the following steps: - preparation of a solution (5) comprising the nanotube (2), nano-objects of the first type (3) and nano-objects of the second type (4), said nano-objects being dispersed in the solution (5), - encapsulation of nano-objects of the first type (3) and of nano-objects of the second type (4) in the nanotube (2).

13. A method according to claim 12, wherein a ratio, in said solution (5), between the concentration of nano-objects of the first type (3) and the concentration of nano-objects of the second type (4) is determined so as to obtain a given average spacing between the nano-objects of the first type (3).

14. A method according to claim 12 or 13, wherein a ratio, in said solution (5), between the concentration of nano-objects of the first type (3) and the concentration of nano-objects of the second type (4) is between 1 / 250 and 1 / 500.

15. Use of a device (1) according to any one of claims 1 to 11 as a probe for bio-imaging, as a single photon source, as a super radiant device, or for the formation of a fluorescent coating whose fluorescence duration is predetermined.

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