1200 results about "Perovskite solar cell" patented technology

The invention relates to a perovskite solar cell and a preparation method thereof. The perovskite solar cell is composed of an FTO glass substrate, a sandwich structure TiO2/ZnO/TiO2 compact layer, a TiO2 mesoporous/perovskite structure material active light absorption layer, a spiro-OMeTAD hole transferring layer and a gold electrode. Compared with the prior art, the sandwich structure TiO2/ZnO/TiO2 compact layer combines with the advantages and disadvantages of TiO2 and ZnO, so that fill factors of the perovskite solar cell are improved to 70%, and the photoelectric conversion efficiency reaches 12.6%. Equipment for preparing the perovskite solar cell is simple, the preparing process is simple, control is easy, the cost is low, and the perovskite solar cell has a very good industrial application prospect.

The invention discloses a perovskite solar cell and a preparation method of the perovskite solar cell by a solution method. The perovskite solar cell comprises a substrate, a transparent electrode, an electron transfer layer, a light absorption layer, a hole transfer layer and a top electrode which are sequentially laminated, wherein the light absorption layer is a photovoltaic material light absorption layer in a perovskite structure. The electron transfer layer, the perovskite material light absorption layer and the hole transfer layer can be prepared by the solution method in a low-temperature (below 200 DEG C) air environment, and particularly, the electron transfer layer does not require nano particles treated or synthetized at a high temperature (above 450 DEG C), so that a technological process can be simplified, the cost is lowered, the preparation efficiency of the cell is improved, and mass production is achieved.

The invention relates to an organic and inorganic hybrid perovskite-based solar cell and a method for manufacturing the same. The organic and inorganic hybrid perovskite-based solar cell comprises a substrate, a transparent electrode, an electron transport layer, an ultrathin orientation layer, a perovskite light absorption layer, a hole transport layer and a counter electrode. The transparent electrode, the electron transport layer, the ultrathin orientation layer, the perovskite light absorption layer, the hole transport layer and the counter electrode are sequentially stacked on the substrate. The method includes modifying micro-nano structures on the surfaces of the electron transport layer or the hole transport layer to form the ultrathin orientation layer before the perovskite light absorption layer is manufactured by the aid of a liquid phase process. The organic and inorganic hybrid perovskite-based solar cell and the method have the advantages that orientated growth of crystals of perovskite is controlled under large-ring structural effects of molecules in the ultrathin orientation layer, accordingly, the crystallization regularity can be improved, and internal defects can be reduced; the diffusion lengths of current carriers inside the perovskite light absorption layer can be effectively increased, accordingly, recombination of electron-hole pairs on the inside and interfaces of the perovskite light absorption layer can be prevented, and the photoelectric conversion efficiency and the stability of the cell can be obviously improved; the crystallization quality of the perovskite light absorption layer cannot be easily affected by film forming conditions under the orientation mold plate effects of the ultrathin orientation layer, accordingly, the device manufacturing repeatability can be improved, and the low-temperature solution method is applicable to industrially producing large-area perovskite solar cells.

The invention discloses a trans-planar perovskite solar structure based on a doped NiO hole transport layer and a preparation method thereof, and belongs to the field of new material solar cells. The perovskite solar cell in the prior art has problems such as poor stability and poor photoelectric conversion performance. The invention provides a trans-planar perovskite solar cell based on a doped NiO hole transport layer. The preparation method of the solar cell comprises the following steps: depositing a NiO dense layer doped with Mg, Li and other hetero atoms of certain concentration on a conductive substrate as a hole transport layer; preparing a perovskite film, wherein the perovskite film is made of APbX3, A=CH3NH3+ or CH(NH2)2+ or the mixture of the two, and X=Cl-, Br- and I- or the mixture thereof; depositing an electron transport layer PCBM; depositing an interface modification layer (including one of LiF, BCP and TiOX); and finally, depositing a layer of metal electrode (Ag or Al). By using the doped NiO dense film as a hole transport layer, the cell has stable and efficient performance, and the hysteresis is small. Industrialization of the perovskite solar cell is easy to realize.

The present invention relates to a perovskite solar cell, which comprises a first electrode substrate; a perovskite material layer comprising a perovskite organic-inorganic material and a polymer additive, wherein the perovskite material layer is disposed above the first electrode substrate; and a second electrode, which is disposed above the perovskite material layer and corresponds to the first electrode substrate. The coverage of the perovskite material layer on the electrode or an electron-transport layer is significantly improved, and the roughness thereof is also decreased, thereby increasing the photoelectric conversion efficiency of the perovskite solar cell.

The invention relates to a perovskite solar cell and a method for manufacturing the same. The perovskite solar cell comprises an FTO (fluorine-doped tin oxide) transparent conducting glass substrate, an electron transport layer, a light absorption layer, a hole transport layer and a metal electrode. The light absorption layer is made of (C<6>H<5>CH<2>CH<2>NH<3>)<2>(CH<3>NH<3>)<n-1>Pb<n>I<3*n+1> (the n is equal to 1 or 2) materials which are of two-dimensional layered structures. The perovskite solar cell and the method have the advantages that the layered perovskite light absorption layer is manufactured by the aid of a spin coating process, the method is simple and is excellent in film-forming property, the materials of the light absorption layer can be changed along with the layer number n, gaps of the materials can be adjusted, and the materials are excellent in chemical stability and still can keep the excellent layered structures without chemical decomposition after being exposed at high air humidity (50-80%) for 30 days, solar cell prototype devices with excellent and stable performance can be obtained, and the perovskite solar cell and the method are favorable for promoting perovskite solar cell commercialization progress.

The invention discloses a perovskite solar cell. The perovskite solar cell is characterized by sequentially comprising a conductive glass layer, a compact titanium dioxide film, a porous titanium dioxide film, a methylamine lead iodine polycrystalline film, a hole-transport material layer and an evaporation silver electrode layer. Interface modification is carried out on the methylamine lead iodine polycrystalline film through long-chain alkyl silane coupling agents, and the number of carbon atoms of the long-chain alkyl silane coupling agents is larger than six and smaller than sixteen. The invention further discloses a manufacturing method of the perovskite solar cell. Compared with the prior art, the perovskite solar cell and the manufacturing method have the advantages that as interface modification is carried out through the long-chain alkyl silane coupling agents, the recombination of electrons in the cell can be suppressed, and the stability of the cell in the wet environment can be improved.

An perovskite solar cell including a substrate; a first electrode provided on the substrate; an electron transport layer, including an electron transporting compound, provided on the first electrode; a perovskite compound layer, including a perovskite compound, provided on the electron transport layer; a hole transport layer, including a hole transport compound, provided on the perovskite compound layer; and a second electrode provided on the hole transport layer. The perovskite compound can be expressed by the general formula X_αY_βM_γ, where X is a halogen atom, Y is an alkylamine compound, M includes a mixture of lead and antimony, and a ratio of α:β:γ is 3:1:1.

The invention relates to a novel method for preparing a perovskite thin film. The novel method comprises a step of carrying out organic amine processing on a prepared perovskite precursor thin film, thereby preparing the perovskite thin film. According to the invention, the preparation technology is simple; cost is low; surface roughness of the thin film is low; crystallinity is high; and the novel method is applicable for preparing a large number of highly-efficient perovskite solar cells, light emitting diodes, light sensing elements and laser devices.

The invention relates a method for manufacturing a high-quality perovskite thin film. The main steps are that organic amine treatment is carried out on powder or crystals of a precursor of perovskite, and then the powder or the crystals of the precursor of the perovskite are converted into liquids. The liquids are subjected to film forming technology to manufacture the high-quality perovskite thin film. The perovskite thin film manufactured through utilization of the technical process is controllable and uniform in thickness and good in crystallinity. The technical process is simple in operation and lower in cost, and is applicable to manufacturing highly efficient perovskite solar cells, light emitting diodes, photosensitive elements and laser devices in a large-sized mode.

The invention discloses a planar heterogeneous perovskite solar cell and a preparation method thereof. The planar heterogeneous perovskite solar cell comprises a substrate and a transparent electrode, a compact layer, an interface modification layer, a perovskite light-absorbing layer, a hole transferring layer and a counter electrode which are sequentially overlapped on the substrate. According to the planar heterogeneous perovskite solar cell, the interface modification layer is added between the compact layer and the perovskite light-absorbing layer, the interface of the compact layer is modified to form an ultrathin passivation layer, so that perovskite light-absorbing layer film formation quality is modified, interface contact resistance is reduced, the perovskite light-absorbing layer and the hole transferring layer are prevented from directly contacting, the perovskite light-absorbing layer is prevented from decomposing, production of electronic reverse compounding and leakage current is reduced, and thereby photoelectric conversion efficiency and stability of the cell are significantly improved.

The invention belongs to the field of a solar cell, and discloses a perovskite solar cell. The perovskite solar cell sequentially comprises a transparent conductive substrate, an electron transmission layer, an interface modification layer, a modified perovskite active layer, a hole transmission layer and a positive electrode, wherein the electron transmission layer is a nanometer TiO2 particle layer, and the interface modification layer is a fullerene derivative layer. A sol-gel method is employed, high-crystallization TiO2 nanoparticles are synthesized by taking titanium tetrachloride is used as a precursor, the TiO2 nanoparticles are applied to the perovskite solar cell by employing a low-temperature annealing process, a fullerene derivative is directly spin-coated on a surface of the obtained nanometer TiO2 particle layer for modification, the defects in TiO2 and perovskite are passivated, a novel perovskite synthesis path is employed, the obtained perovskite solar cell has high efficiency and does not have hysteresis effect under a low-temperature preparation process, and the device can be used for stable transmission; and moreover, the related preparation method is simple, is low in energy consumption and is suitable for promotion and application.

The invention discloses a perovskite solar cell preparation method based on the full-coating process, and relates to solar cells. The perovskite solar cell preparation method based on the full-coating process is low in cost, high in efficiency and industrialized. The method comprises the steps that (1) an electron transfer layer, a perovskite active layer and a hole transfer layer are sequentially prepared on a transparent conductive substrate by the adoption of the coating process, and slot-die coating or spraying-type coating is adopted in the coating process; (2) the hole transfer layer is coated with a top electrode, and screen printing and knife coating are adopted for coating. The problem of the process and cost of evaporation and precious metal electrode printing are solved, and the problem that the perovskite layer may be damaged by high-temperature carbon paste is solved. The one-step annealing method is adopted, in other words, annealing is carried out at the temperature ranging from 70 DEG C to 150 DEG C after coating is carried out on all the functional layers. The manufacturing technology is further simplified, and the device performance and stability can be effectively improved.

The invention relates to a perovskite solar cell with interface modification layers. The cross-sectional structure of the perovskite solar cell includes a transparent conductive substrate, a first transmission layer, a perovskite active layer, a second transmission layer and a back electrode; at least one first interface modification layer is disposed between the perovskite active layer and the first transmission layer; and no or at least one second interface modification layer is disposed between the perovskite active layer and the second transmission layer. The invention also discloses a preparation method of the perovskite solar cell. According to the method, the interface modification layers are additionally arranged between the perovskite active layer and transmission layers of a perovskite solar cell, so that the perovskite solar cell with the interface modification layers can be prepared; the surfaces of the transmission layers are passivated; the crystal structure of the perovskite is optimized; ion migration in the perovskite active layer is suppressed to a certain extent; and therefore, the photoelectric conversion efficiency and long-term stability of the perovskite cellare improved.

The invention provides a preparation method for a perovskite type solar cell based on a spraying technology. Concretely, a transparent conductive substrate is sequentially sprayed with a hole transfer layer, a perovskite active layer, an electron transfer layer and a top electrode to prepare the perovskite type solar cell. The quality and performance of the solar cell can be regulated and controlled by changing different parameters of the spraying technology. The preparation method is easy to implement, can prepare the efficient and low-cost perovskite type solar cell and has good industrialization prospects.

The invention provides a perovskite solar cell preparation method. The preparation method comprises the following steps: (1) substrate cleaning and ozone treatment are carried out; (2) spin coating of a hole transport layer is carried out; (3) a water-doped CH3NH3PbI3-xClx precursory solution is prepared; (4) spin coating of the CH3NH3PbI3-xClx precursory solution is carried out; (5) spin coating of an electron transport layer is carried out; (6) spin coating of an interface modification layer is carried out; and (7) vacuum evaporation of a metal cathode is carried out, and thus, a perovskite solar cell is obtained. The perovskite solar cell obtained by the preparation method provided by the invention has the advantages of high photoelectric conversion efficiency and good cell stability.

The invention relates to a bulk-heterojunction perovskite thin film, a production method thereof and a solar cell. The bulk-heterojunction perovskite thin film comprises a bulk-heterojunction layer and a perovskite thin film layer located on the surface of the bulk-heterojunction layer, wherein the bulk-heterojunction layer comprises a perovskite polycrystalline thin film serving as an electron donor material and an electron acceptor material located at the crystal boundary position of the perovskite polycrystalline thin film. The bulk-heterojunction perovskite thin film has the advantages that when the bulk-heterojunction perovskite thin film is applied to the perovskite solar cell, the bulk-heterojunction perovskite thin film can replace an existing mesoporous electron transfer layer and an existing perovskite light absorption layer, and accordingly the structure of the cell can be simplified; the high-temperature sintering process needed by the production of the independent mesoporous layer can be omitted, and the bulk-heterojunction perovskite thin film is suitable for producing the efficient and flexible perovskite solar cell on a plastic substrate.

The invention discloses a semitransparent perovskite solar cell and a preparation method thereof. The semitransparent perovskite solar cell comprises a transparent conductive substrate a, an inorganic electron transport layer, a light capturing layer, an inorganic hole transport layer and a transparent conductive substrate b, wherein the light capturing layer is made of a DXZ3 type perovskite material; D is selected from Cs<+>, CH3NH3<+>, CH(NH2)2<+>, or a mixture thereof; X is selected from Pb<2+>, Sn<2+>, Ge<2+> or a mixture thereof; and Z is selected from Cl<->, Br<->, I<-> or a mixture thereof. According to the perovskite solar cell with the electron transport layer and the hole transport layer which are made of a full inorganic material, defects of high cost and stability reduction in organic materials are eliminated, and battery stability is greatly improved. Furthermore, the perovskite solar cell is prepared through a physical extrusion method, thereby realizing simple preparation process and high uniformity of the perovskite film. The perovskite solar cell further has advantages of low cost, excellent and stable performance. Furthermore commercial application of the perovskite solar cell is promoted.

A method of fabricating a large-area perovskite film includes steps of: providing a precursor solution on a conductive substrate to form a film, wherein the perovskite is represented by a formula of ABX₃, and the solutes of the precursor solution at least comprises A, B and X; and applying an anti-solvent or Infrared light on the film. The fabrication methods of a large-area perovskite film and a perovskite solar cell or module are also disclosed.

The invention discloses a preparation method for a cesium lead bromide inorganic perovskite thin film and a photovoltaic device based on the cesium lead bromide inorganic perovskite thin film. An unstable yellow oblique-phase CsPbI3 thin film is prepared by employing a one-step solution method and then is converted to a stable black cubic-phase CsPbBr3 thin film by employing a Br2 steam thermal injection gas-phase deposition method. Gas-phase exchange reaction of halide ions is utilized, I<-> in CsPbI3 is substituted by Br<-> with smaller radius, the purpose of lattice shrinkage, phase changesuppression and stability improvement are achieved, the bottleneck problem that Br solubility of a traditional one-step solution method is limited can be effectively solved, and the problems that thethin film is easy to fall during immersion of a two-step solution method also can be prevented; and meanwhile, the prepared CsPbBr3 thin film is also used as a light absorption layer to prepare an FTO/c-TiO2/m-TiO2/CsPbBr3/C perovskite solar cell with an all-inorganic structure, the photoelectric efficiency of a battery in initial batch reaches 3.23%, and the battery shows favorable long-term stability.

A method of fabricating a perovskite solar cell includes forming a hole transport layer on a transparent electrically conductive substrate, and forming a perovskite layer on the hole transport layer via a two-stage vacuum evaporation process. Then, an electron transport layer and an electrode layer are formed in order. The two-stage vacuum evaporation process includes first vacuum evaporating a first material on the hole transport layer and then vacuum evaporating a second material on the first material so as to react the first material with the second material in situ and form the perovskite layer.

The invention discloses a perovskite solar cell containing a hydrophilic electrode modification layer and preparation method, and belongs to the field of novel photovoltaic solar cells. The device structure includes a metal counter electrode (Au), a hole transport layer (Spiro-OMeTAD), a hydrophilic electrode modification layer (MPc), a perovskite active layer (CH3NH3PbI3), an electron transport layer (TiO2) and an FTO conductive glass substrate in sequence from bottom to top; and the hydrophobic electrode modification layer is a metal phthalocyanine compound, on the basis of a traditional FTO/TiO2/CH3NH3PbI3/spiro-OMeTAD/Au device structure, through introduction of a hydrophobic metal phthalocyanine compound thin film with no surface function group modification between a perovskite light absorption layer and the hole transport layer as the electrode modification layer, corrosion of water in air to a perovskite material can be effectively stopped, long-time stability and illumination stability of the perovskite solar cell device are remarkably improved, and the perovskite solar cell provided by the invention has good application prospects.

The invention relates to an organic inorganic hybrid perovskite film and a manufacturing method of a perovskite solar cell. A chemical formula of the perovskite film is ABX3, wherein the A is a positive ion of organic amine; the B is at least one of Pb<2+>, Sn<2+>, Ge<2+>, Co<2+>, Fe<2+>, Mn<2+>, Cu<2+> and Ni<2+>; and the X is at least one of Cl<->, Br<-> and I<->. The manufacturing method comprises the following steps of (1) carrying out spin coating on a halogenide solution of the B on a substrate and acquiring a halide film of the B; and (2) placing a halide powder of the A in a closed cavity and placing the halide film of the B acquired through the step (1) at a position with a certain height above the halide powder of the A as a mode of facing the halide powder of the A so that pressure in the cavity is less than 5 kpas, and carrying out heat preservation for 10 mins-24 hs at 80-150 DEG C so that the perovskite film can be obtained. A surface of the manufactured perovskite film is flat, a grain is large and a grain boundary is small so that excellent photovoltaic conversion performance is possessed.

The invention discloses a method for manufacturing a high-efficiency perovskite type solar cell through large crystal grain forming. The method for manufacturing the high-efficiency perovskite type solar cell through large crystal grain forming at least sequentially comprises the steps that hole (or electron) transport layer materials, perovskite type materials, electron (or hole) transport layer materials and electrode materials are grown on a conducting substrate. The performance of the cell can be improved greatly by improving crystal grain forming of the perovskite type materials. During manufacturing, two kinds of precursor materials need to be dissolved in a solvent, so that a yellow mixing solution is obtained, the temperature of the yellow solution needs to be kept between 65 DEG C and 80 DEG C all the time before spin coating, the temperature of the substrate is kept between 170 DEG C and 200 DEG C, spin coating needs to be conducted at the spinning speed of 3500-5000 rpm for about one to three seconds instantly after the yellow solution is dripped on the substrate, then rapid cooling is conducted for about three to five seconds till the temperature reaches 50 DEG C, then natural cooling is conducted till the temperature reaches an indoor temperature, in this way, a yellow film can be changed into a dark brown film, and large crystal grain forming can be observed at the same time.

The invention provides a method for preparing a perovskite thin film in a perovskite solar cell via a solution air extraction and ventilation method. The method comprises the following steps: a perovskite liquid film coated on a surface of a base body is subjected to air extracting and drying operation in an environment where the partial pressure of the solvent is lower than 99% saturated vapor pressure of the solvent at current temperature; during drying processes or after the perovskite liquid film is completely dries, a gas which does not react chemically with a perovskite is let in, and therefore a process that the solvent is evaporated or solvent molecules leave the environment can be accelerated via solvent molecule concentration dilution. Heterogeneous nucleation and growth of the surface of the base body can be realized via control over drying process conditions, and therefore a uniform and compact perovskite thin film can be formed. The method can be used for accelerating liquid film drying processes, making solvent steam molecules leave a surface of the thin film quickly, and obtaining the uniform-structured and compact perovskite thin film; thus current leakage caused by perovskite thin film loopholes can be prevented and the method can help make high-efficiency solar cells; the method is advantaged by simple operation, easy-to-implement property, low cost, high repetition accuracy, convenience for industrialization and the like.

The invention relates to a flexile and large-area perovskite solar cell module and a preparation method thereof. The perovskite solar cell module comprises a metal back reflection layer, an electron transmission layer, a perovskite absorption layer, a cavity transmission layer, a transparent conductive front electrode, transparent packaging glue and a flexible and transparent plastic cover plate, which are stacked on a flexible substrate in sequence; light enters from a direction of the flexible and transparent plastic cover plate; the metal back reflection layer, the electron transmission layer, the perovskite absorption layer, the cavity transmission layer and the transparent conductive front electrode are separated by pre-set separation grooves to form a plurality of sub-cells which are connected in series. The flexile and large-area perovskite solar cell module has no requirements on permeability and conductivity of the substrate and the common and cheap flexible substrate can be adopted, so that the cost is remarkably reduced; the preparation method is simple in process, the rate of finished products is high and large-scale production is easy to realize; on the basis of not influencing performances of a perovskite solar cell, adverse effects on the perovskite solar cell, caused by external factors including water vapor, chemical corrosion, external stress and the like, can be avoided, and the reliability of the cell is improved.

The invention relates to a perovskite solar cell with a nano light trap structure and a preparation method thereof. The perovskite solar cell comprises sequentially stacked substrate, transparent electrode, first transmission layer, perovskite light absorbing layer, second transmission layer, buffer layer and metal electrode, wherein the second transmission layer is provided with the nano light trap structure. According to the perovskite solar cell and the preparation method thereof, the light absorption can be effectively increased in a wide spectral range from ultraviolet to infrared, thus the photoelectric conversion efficiency of the perovskite solar cell is significantly improved, the preparation process is simple, the cost is low, and the perovskite solar cell is suitable for mass production.

The invention provides a method for preparing a perovskite thin film in a perovskite solar cell via a solution air extraction method. The method comprises the following steps: a perovskite liquid film coated on a surface of a base body is subjected to air extracting and drying operation in an environment where partial pressure of the solvent is lower than 99% saturated vapor pressure of the solvent at current temperature; heterogeneous nucleation and growth of the surface of the base body can be realized via control over drying process conditions, and therefore a uniform and compact perovskite thin film can be formed. The method can be used for obtaining the uniform-structured and compact perovskite thin film, thus current leakage caused by perovskite thin film loopholes can be prevented and the method can help make high-efficiency solar cells; the method is advantaged by simple operation, easy-to-implement property, low cost, high repetition accuracy, convenience for industrialization and continuous production and the like.

The invention relates to a perovskite photovoltaic cell with bilayer nanometer mesoporous electron-transporting layer and preparation method thereof. The cell comprises a conducting substrate, an electron-transporting layer with double-layer structure, a perovskite light absorption layer, a hole-transporting layer and metal electrodes. The perovskite photovoltaic cell with bilayer nanometer mesoporous electron-transporting layer has the advantages that the SnO2 with one step method low-temperature growth, is used as the electron-transporting layer in the photovoltaic cell, replaces the TiO2 electron-transporting layer with two steps method high temperature sintering, and the preparation process is simplified. The mesoporous perovskite photovoltaic cell prepared with one step low-temperature growth method obtains 13.82% of highlight electricity transfer efficiency, and reduces the manufacturing cost effectively at the same time. Compared with a planer construction, the mesoporous structure used in the perovskite photovoltaic cell is liable for the adherence of the perovskite light absorption material. SnO2 conducts a smaller dissimilation on the perovskite light absorption layer than the TiO2 does, the performance and stability of the cell are improved in this way. The perovskite photovoltaic cell with bilayer nanometer mesoporous electron-transporting layer and preparation method thereof plays a great promoting role in the development and popularization on the flexible solar cell, and further promotes the industrialized application on the perovskite solar cell.

The invention relates to a novel process for preparing an organic-inorganic perovskite thin film through adopting an experimental scheme in which two kinds of metal compounds are adopted as precursors. With the novel process adopted, an efficient solar battery device with a planar structure can be prepared. According to the novel process, the two kinds of metal compound precursors are compounded, and therefore, a pinhole defect of the perovskite thin film can be effectively avoided, and compound of electrons and holes can be alleviated, and short-circuiting risks of the perovskite thin film can be decreased. The novel process of the invention belongs to the photoelectric material field and is characterized in that the two kinds of metal compounds are selected as a source of metal ions in a perovskite material, wherein the general formula of the organic-inorganic perovskite material is ABX3, wherein A is CH3NH3 or NH2-CH=NH2, B is Pb or Sn, and X is I or Br. With the preparation method adopted, the thickness of the perovskite thin film is uniform, and the crystallinity of the perovskite thin film is high, the perovskite thin film can have high electron and hole transport ability. The preparation method is suitable for large-area preparation of organic-inorganic perovskite solar battery devices with planar structures.