WO2011158995A1 - Dual-film structure fto production method - Google Patents

Abstract

The present invention relates to a dual-film structure FTO production method, and the invention comprises the steps of: heating a substrate to between 400 and 500 degrees; producing flat FTO by spraying a precursor containing Sn onto the heated substrate; heating the flat FTO film to at least between 500 and 550 degrees; and forming an FTO nanorod layer by spraying a precursor containing Sn onto the heated FTO substrate. A characterising feature of the present invention is that a polycrystalline FTO film is formed in the bottom part, and a nanorod FTO layer is formed by being grown on the polycrystalline FTO film.

Description

FTO manufacturing method with double membrane structure

The present invention relates to a FTO film manufacturing process technology having a novel double layer structure in which a flat FTO (doped tin oxide) film is provided in the lower layer and an FTO nanorod layer is formed in the upper layer.

In addition, the present invention relates to a multi-layered FTO film production technology and a solar cell structure technology using the multi-layered FTO film, characterized in that additional layers may be provided above and below the double layer FTO film.

Transparent conductive film TCO (Transparent Conducting oxide) material is mainly composed of metal oxide and has been studied mainly on n-type semiconductor. In general, oxide transparent conductive films such as SnO 2, ZnO, and In 2 O 3 are manufactured by using physical and chemical vapor deposition methods, and a large area roll-to-roll coating technology using a sputtering method has recently been actively studied in the industry. ITO transparent conductive films are most commonly used in the display and touch panel fields, while FTO is the most widely used for next-generation thin-film silicon solar cells (Thin-Si) and dye-sensitized solar cells (DSSC). This is because of the high temperature heat resistance (about 500 degrees) and the excellent chemical and corrosion resistance of the FTO thin film only. In addition, research on various transparent oxide semiconductors such as AZO and ZnO has been conducted.

FTO manufacturing process technology is typically produced by spray pyrosol and atmospheric CVD. In the former case, the liquid FTO precursor solution is misted in the gas phase (microdroplets: mixed solution such as Sn, F-containing precursors, solvents, and additives), and then coated on a heated substrate. In the latter case, the Sn-F-free solution is coated. It is a technology that coats a cursor by evaporating it at the molecular level and sending it onto a heated substrate.

FTO substrates prepared by conventional spray pyrosol and CVD methods are flat and low haze substrates. Haze is a very important physical property required in devices such as solar cells, and the incident light is scattered in the solar cell to stay for a long time to increase the efficiency of the photoabsorption reaction by photons. Therefore, the solar cell efficiency may differ by more than 1% depending on the degree of haze.

In particular, other TCOs can control the surface roughness through etching through the acid, thereby controlling haze to some extent. However, chemical resistance, which is an advantage of FTO, is rather a disadvantage, making etching through acid very difficult. Thus, some attempts have been made to produce high haze substrates by controlling surface grains through difficult processes. However, these reported FTOs all belong to flat FTO due to the limitation of surface morphology control.

In the present invention, a high-conductivity / high-haze type novel double layer structure FTO membrane having both advantages (high conductivity and good durability) and high-haze physical properties of FTO nanorods was attempted.

Such physical properties can be achieved by forming “bottom flat FTO layer and FTO nanorod layer on top”, which is the best of the new and announced solar cell substrates.

In addition, such a double layer FTO film exhibits a very surprising phenomenon in which almost all of the disadvantages of the films included in each layer (flat FTO film: low haze properties, nano-bar FTO film: physical collapse and weak durability) disappear.

The physical properties that suppress the shortcomings of the individual films and bring about the advantages of the individual films indicate that they can be used in various industrial fields such as touch panels, sensors, heaters, as well as next-generation solar cell substrates.

1 shows the concept of the present invention. In general, plate-type FTO is made by atmospheric pressure CVD and spray pyrosol, and according to a conventional polycrystalline film growth mechanism, the growth of nanonuclei on the substrate of the first nanoparticles is gradually grown into micro grain crystals. As shown in FIG. 1, the nanorod-type FTO film also has a state of being grown vertically on the substrate in a columnar shape based on the nanoparticle-type nuclei. However, unlike the flat FTO, due to the weak coupling of the voids and the roots (nanoparticles) at the top, it has a weak electrical conductivity property and the vulnerability to fall outside shock or physical stimulus. On the other hand, the plate-like FTO shows the same interface structure but has high durability against high electroconductivity and physical external pressure due to the dense polycrystalline micrograins grown thereon.

The double layer structure in which the FTO nanorods are grown on the plate-shaped FTO film of FIG. 1 almost disappears the problems occurring in the individual layers, and rather, an interesting phenomenon appears that mutual properties are advantageous.

This is because when the FTO nanorods are grown on the plate-shaped FTO, the nucleus grows in the columnar shape from the vertices of the polycrystalline upper portion of the plate-shaped FTO to form the FTO nanorods, and the lower polycrystalline grains and the upper nanorods are interfacial. It shows a well-bonded structure, which tends to break rather than collapse.

In addition, FIG. 2 shows a slight application of the concept of FIG. 1, which can be applied to not only flat substrates but also curved (complex) substrates.

In addition, FIG. 2 shows that by applying another coating on the upper FTO nanorod, a multilayer structure film containing a bilayer FTO film exhibiting more various functionalities (such as a catalyst) can be formed.

In addition, FIG. 3 shows that the FTO film having a double layer structure can be more efficiently used for large area solar cells by preforming a metal mesh under the flat FTO.

In addition, FIG. 3 shows that SiO 2 and TiO 2 may be coated as a barrier film in the case of ordinary glass.

The substrate of the present invention can be applied to all planes, curved surfaces, and complex shapes, and the principles for implementing the present invention are the same.

Substrates of the present invention may be glass, thin glass, ultra-thin thin film (glass ribbon, glass roll), ceramic substrate, metal substrate, plastic substrate (polyimide and nanoclay composite, etc.), etc. The principle is the same.

In addition, the coating formed on the upper portion of the FTO nanorods may be metal, ceramic, polymer, transparent conductive film, oxide, semiconducting material, insulating material, nanoparticle, nanowire, nanoplate, nitride, sulfide, boron compound, carbon, nano Carbon, silicon, silica, organic compounds, organometallic compounds, alkali compounds, salts, inorganic compounds, biomaterials, biochemicals and the like can be.

In addition, the coating formed on the upper portion of the FTO nanorod may be various transparent conductive films based on oxide metals or ceramics such as ITO, AZO, ZnO, SnO 2, IZO, GZO, TiO 2, and the like.

In addition, the coating method of the coating formed on the upper part of the FTO nanorods is polymer coating (deep coating, spin coating, etc.), ceramic coating (sol-gel coating, sputtering, CVD / PVD, plating, etc.), metal coating (electrolytic / Electroless plating, sputtering, CVD / PVD, etc.), semiconducting / semiconductor coatings (plating, CVD / PVD, inkjet, spray, etc.), nanocolloidal coatings and the like can be utilized. In the present invention, a representative example was performed through a polymer dip coating, ITO sputter coating, and platinum sputter coating method (see Examples).

In addition, even when the transparent conductive film is formed of ITO, AZO, ZnO, SnO 2, IZO, GZO, TiO 2 on the lower FTO nanorod layer without applying FTO, the principles of the present invention can be similarly applied.

The glass used in the present invention is typically glass (soda lime glass), aluminum oxide borosilicate glass, glass for LCD, low iron glass (Low-Fe glass, iron 150 ppm or less), tempered glass, low thermal expansion glass, automotive Glass and the like can be used. In particular, in the case of ordinary glass, there is an advantage of low cost, but sodium ions climb up to the top during the heat treatment and prevent the formation of FTO nanostructures. For this purpose, a conventional SiO 2 or TiO 2 barrier film is provided.

The present invention is to develop a next-generation thin film silicon by developing an FTO substrate having a double-layered structure having high heat resistance, excellent acid chemical resistance, high haze optical properties, good electrical conductivity, and high specific surface area (catalytically active substrate), which has not been provided before. As well as substrate materials for solar cells (Thin-Si) and dye-sensitized solar cells (DSSC), new materials such as touch panel sensors, pressure sensors, gas sensors, biosensors, surface heating elements, optical control substrates and catalytically active substrates It can be utilized as.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a comparison diagram of a flat FTO substrate, a FTO substrate having a rod structure, and a FTO substrate having a double film structure in which these two kinds of films are bonded to each other by an upper portion.

FIG. 2 shows that the double layer structure FTO can be formed equally on the basis of the curved substrate, and shows that the FTO nanostructures having the triple layer structure can be formed through the additional coating.

3 is a conceptual view showing that a barrier film may be formed on a substrate in advance, or a metal grid may be formed, and a FTO film having a double layer structure may be formed thereon, which may be used in a next-generation solar cell.

4 is a comparative FE-SEM photograph of a flat plate type FTO film (a) and a nanorod type FTO film (b).

FIG. 5 shows a double film in which a flat FTO film (a) and a FTO film (b) having a double film structure of the present invention are used to form a flat FTO using a two-step process and on which a FTO nanostructure is formed.

FIG. 6 is a FE-SEM photograph showing that nuclei are grown and grown at upper edges (vertexes, etc.) of a lower polycrystalline grain in a double layer structured FTO film. FIG.

FIG. 7 shows the FTO nanostructure morphology change when using water as a solvent and water / methanol mixed solvent in the spray pyrosol method (water: thin rhombic cross section, water / ethanol: coarse square cross section).

8 is a result of performing a platinum nanoparticle coating on the upper layer FTO nanorod of the present invention through the platinum sputter.

9 is a schematic diagram and a cell photograph of a dye-sensitized solar cell having a double layered FTO film.

10 is a conceptual view of a thin film silicon solar cell having a double layered FTO film.

Example 1 Process Equipment and Process Technology

The lower planar FTO film and the upper FTO nanorod layer can be formed both using the Spray Pyrosol principle and the atmospheric pressure CVD principle. In these two methods, the precursors may be injected at a predetermined angle with the side part and the direction perpendicular to the direction of the substrate and the upper part or the direction perpendicular to the substrate, and the exhaust part may be provided at the side or the upper part.

Most importantly, the growth conditions for plate-type FTO and nano-rod FTO are at temperature. Flat FTO is optimally formed within 400-500 degrees and FTO nanorods are optimally grown at 500-550 degrees or more (optimally 500-550 degrees or more). This condition applies similarly to both spray pyrosol and atmospheric CVD methods, and the present invention will be described using the more demanding spray pyrosol method.

Example 2: Plate FTO and FTO Nanostructure Formation Conditions

FTO membrane is sprayed through the micro-droplet state by spray coating or ultrasonic spraying method of FTO precursor solution and then sprayed through the nozzle part of the side part or the upper part, and the exhaust is performed properly, the plate FTO or FTO nano according to the temperature condition of the heated substrate Growth occurs in a completely different form with a rod. In particular, growth occurs to the largest length ratio of FTO nanostructures above 550 degrees or 580 degrees. These temperature conditions are believed to activate the growth conditions of the FTO polycrystalline grains to activate the movement of ions and atoms in the crystal and to induce unidirectional growth, resulting in morphology change in the z-axis direction.

In addition, the FTO precursor sends droplets from the upper layer to the substrate and at the same time flow control through an exhaust vent located in the upper layer, allowing the formation of FTO nanostructures in the range of 400-500 degrees, as well as 500-550 degrees or more. .

In the spray pyrosol and atmospheric spray coating method of the present invention, the precursor of tin oxide is Sn-containing organometallic compound precursor such as SnCl 4 · 5H 2 O, (C 4 H 9) 2 Sn (CH 3 COO) 2, (CH 3) 2 SnCl 2, (C 4 H 9) 3 SnH, SnCl 4, etc. Can be used. The fluorine compound serving as a fluorine source doped with tin oxide may be various fluorine sources such as NH 4 F, CF 3 Br, CF 2 Cl 2, CH 3 CClF 2, CF 3 COOH, CH 3 CHF 2, HF, and the like. The Sn / F ratio is mixed so as to be a predetermined ratio to produce an FTO precursor. For solvent, water and alcohol system can be used. For safety, water and ethanol system can be used and water and ethanol can be mixed. Typically 5wt% ethanol (relative to H20) may be used as the solvent.

More specifically, the FTO precursor solution is sprayed onto the substrate along with the carrier gas through the nozzle, and the sprayed micro droplets are deposited on the substrate. At this time, the deposition chamber is provided with an appropriate exhaust system to extract the reaction gas and the unreacted material. The method of forming the precursor microdroplets through the nozzle may use a general spray nozzle and a slit nozzle, but such a method tends to form relatively large droplets. In order to form finer droplets, it is desirable to first form an ultrafine mist precursor by means of ultrasonic spraying and transport it to the deposition chamber as appropriate through a carrier gas system and a vent system. At this time, the substrate can be rotated in the case of batch type. In the case of continuous in-line and roll-to-roll (R2R) coating system, gas curtains (nitrogen knife, etc.) are formed at the lower ends of both sides of the deposition chamber and sealed and transported. It can be possible.

In the final state, atmospheric pressure CVD and spray pyrosol have a similar mechanism. In other words,

(1) Both the spray pyrosol and the atmospheric CVD method control the flow at atmospheric pressure. (2) The basic prototype of precursors uses similar materials, but is used as precursor of each coating method depending on the degree of evaporation or hydration. (3) These precursors are eventually converted to SnO2 in a heated atmosphere of H20, alcohol, O2 and air, and the oxygen of SnO2 is replaced by some F by F-containing precursors contained in the atmosphere. Thus, the process of initial precursor supply and the physico-chemical conversion of precursors in the intermediate stages are different, but in the final state (near the heated substrate), similar thermal-chemical oxidation / doping mechanisms are available for both atmospheric pressure CVD and spray pyrosol. Has However, the instantaneous heat loss felt by the substrate may be different because there is a significant difference in the state and flow amount of the reactants. However, given sufficient heat capacity so that the heat loss of the substrate cannot be felt, and the temperature is sufficiently increased by more than 550 degrees, FTO nanostructures can be formed in the conventional atmospheric pressure CVD method as in the spray pyrosol method.

Example 3 SiO2 and TiO2 Barrier Film Formation Process

In general glass used as a substrate, when heated to 400-600 degrees, impurities such as Na and K diffuse onto the substrate and damage the surface of the glass substrate. This results in a decrease in film adhesion and film quality even when the FTO film is coated. Therefore, a barrier layer coating must be applied between the glass substrate and the FTO film to block impurities from entering. Generally, ceramic films such as SiO2 and TiO2 are used a lot, but in this study, SiO2 barrier films were typically formed by using dip coating and spray coating at about 5-50 nm. SiO 2 barrier films were formed using a dip coating method for small substrates and a spray coating method for large substrates and curved surfaces.

In the dip coating method, a silica sol [ethanol (95%): Tetraethyl silicate: Nitric acid = 90: 11: 0.5 (volume ratio)] was prepared, dip coated at a speed of 150 mm / min, and then heat-treated at 300-400 degrees for 5 minutes. SiO2 barrier film was formed. Spray coating was performed on large area substrates or curved glass substrates. Silane reagents (SiH 4, SiH 2 Cl 2, Si (OC 2 H 5) 2, etc.) can be easily formed on a glass substrate heated to 400-600 degrees in air or in an oxygen atmosphere using the CVD principle (spray). When using high quality glass, ie, when using a glass substrate with few impurities, such as Na and K (for example, borosilicate glass), it is not necessary to form a barrier film.

Tetraethyl silicate ((C2H5) 4SiO4)) 0.05M, Ethyl Alcohol (C2H5OH) 1.54M, and Nitric Acid (HNO3) 0.01M were dissolved in ethanol as specific SiO2 barrier film formation conditions. As a specific TiO2 barrier film formation condition, 0.0089M of Tetra Ethyl Ortho Titanate (C2H5O) 4 Ti 1M 2-methoxyethanol (C3H8O2) was dissolved in C3H8O2 solvent. However, substrates such as LCD glass without sodium ions do not require a barrier film forming process.

Example 4 FTO Precursor Manufacturing Method

The FTO precursor solution was prepared by dissolving SnCl 4 · 5H20 in tertiary distilled water to 0.68 M and dissolving NH 4 F as an F dopant in ethanol to 1.2 M, then mixing and stirring the two solutions and filtering.

In addition, the coating solution was prepared by mixing and stirring SnCl 4 · 5H 2 O to 0.68 M in a solvent in which 5% ethanol was mixed with pure DI water, and synthesized by using NH 4 F as a source of F such that the ratio of F / Sn was 1.76. .

In addition, in the present invention, alcohols and ethylene glycol may be additionally added in addition to the solution composition to prepare various FTO membranes.

In order to control the amount of F doping, the amount of NH 4 F may be changed from 0.1 to 3 M, or 0-2 M of hydrofluoric acid (HF) may be added. Therefore, the precursor solution for preparing the FTO membrane is not limited to the composition shown above.

Example 4 Precursor Micro Droplets (Mistification Method)

The spray source method, the ultrasonic spray coating method, and the ultrasonic spray spray method are separately connected to the precursor source part to obtain the precursor flow by vaporizing the FTO precursor in the gas phase.

Briefly looking at these three micro-droplet precursor forming techniques, the spray coating method is a method of spraying the liquid precursor to the micro-droplets due to the force to attract the liquid when the external gas is expanded through the fine nozzle portion. Ultrasonic spraying is a method in which a liquid precursor is vibrated by an ultrasonic vibrator and atomized by a carrier gas, just like a general ultrasonic humidifier. Finally, the ultrasonic spray spraying method is to change the ultrasonic vibrator portion like a spray nozzle and spray the atomized precursor by spraying principle.

 In the embodiment of FIG. 4, when one ultrasonic terminal (1.6HZ) is used (one nozzle, one exhaust system), the spray pressure is 0.15 MPa and the suction pressure is 520 W. Flow control for homogeneity of the film is possible, and the deposition time of the FTO transparent conductive film is about 25 minutes.

Example 5 Form VIII Formation in Type I FTO Functional Thin Film Formation

However, when compared to 450 degrees (Fig. 4 (a)), when the temperature is raised to 550 degrees, it can be seen that the FTO nanostructure is formed as shown in the photo on the right of Fig. 4 (b). However, as shown in FIG. 1, the nanorods formed by the shock wave (cutting and observing during FE-SEM observation) or the weak physical stimulus of the glass cutting process easily fall down. The reason for this is the fragile interface structure. (As shown in the FE-SEM picture, the nanoparticle powders are formed at the interface very much). This weak durability is a major obstacle to the applicability of the FTO nanorods.

On the other hand, as shown in FIG. 2, when the plate-shaped FTO is formed around 400-500 degrees (FIG. 5 (a)) and the substrate temperature is raised to 550 degrees through a continuous process, the FTO nanorods are grown as shown in FIG. 5 (b). It can be confirmed that the problem occurred in FIG. 4 does not occur. The reason is well illustrated in FIG. 6. In other words, the FTO nanorods in the upper layer grow all the way from the partial protrusions (the vertices or edges of the crystals) of the polycrystalline grains in the lower portion and show that they are integrated. That is, the interface between the conventional nanorod and the substrate shown in Figure 4 (b) is completely different.

FIG. 7 shows that the FTO nanorod shape of the upper layer is changed when the solvent is changed under the conditions of FIG. 6. That is, FIG. 7 (a) shows the case where the solvent is water, and FIG. 7 (b) shows the case where a water / ethanol 5% mixed solution is used. The shape of each cross section is close to the diamond and the transfer square.

As shown in FIG. 8, when Pt was deposited on the FTO layer having a double layer structure by sputtering for about 2 minutes, platinum nanoparticles having a diameter of about 5-20 nm were formed on the FTO nanorods due to the segregation of the interface. Can be. Cressington's magnetron sputterer (MSC200) was used, and the distance between the Pt target and the substrate was fixed at 4 cm and the plasma intensity was maintained at 40 mA during the deposition. The deposition time is 40 seconds. Such a platinum nanocatalyst is used as a core for methanol fuel jersey and the like, and the FTO nanostructure of the present invention can be used as a novel functional membrane because of its excellent specific surface area. By applying other conventional coating techniques, it is expected that semiconductors, semiconductors, metals, polymers, and ceramics may be formed on FTO nanostructures in various forms and used in various devices.

As a result of testing the electrical properties, in the present experiment, if they were formed separately, the electrical conductivity was about 9 Ω in the case of flat FTO, and 80 ohm in the case of FTO nanorods. The sheet resistance is further lowered to 7 ohms.

In addition, as a result of coating about 100 nm of ITO on the FTO bilayer by the sputtering method, the resistance was greatly reduced by about 20% from 7 Ohm to 5 Ohm before the coating. The electrical resistance reduction effect in the triple layer structure can be newly applied as a structure having a lower transparent conductive film, that is, a lower TCO-top FTO nanorod, but the interface bonding property is poor or vulnerable to coating conditions depending on the type of lower TCO. The materials are expected to be difficult to achieve good results, but the theoretical underlying transparent conductive film could be ITO, AZO, ZnO, SnO2, IZO, GZO, TiO2.

The substrate is a metal mesh, SUS316, heat-resistant polyimide substrate can be seen that the plate-like FTO is formed, the principles of the present invention is applied as it is.

Figure 9 is a schematic diagram of a dye-sensitized solar cell made using a transparent conductive film containing a FTO nanostructure having a double-film structure of the present invention. FTO substrates having a double film structure can be usefully used. The TiO2 paste is coated and heat-treated on the transparent conductive film 1 including the FTO nanorods to form TiO2 and adsorb the dye (2). The counter electrode is used with a flat plate FTO (6) and a thin coating of the catalyst Pt (5). The electrolyte is completed by filling the electrolyte (I- / I3-) between the two electrodes. The cell efficiency was only 5.8% using only the flat FTO, but the efficiency increased by about 1% to 6.8% using this FTO nanostructure.

10 is a schematic diagram of a dye-sensitized solar cell made using a transparent conductive film including a FTO nanostructure having a double film structure of the present invention. An FTO nanostructured transparent conductive film having a double film structure was formed (1, 2), and a silicon amorphous thin film was formed thereon (3). In addition, a p-n junction, a p-i-n junction, or a multilayer solar cell structure may be formed by a conventional method (4), and a metal electrode may be formed thereon.

Claims (12)

In the FTO manufacturing method of the double membrane structure, Heat the substrate to 400-500 degrees; Spraying a precursor containing Sn onto the heated substrate to produce a flat plate type FTO; Heating the plate-shaped FTO membrane to 500-550 degrees or more; By spraying a precursor containing Sn onto the heated FTO substrate to form an FTO nanorod layer, A polycrystalline FTO film is formed at the bottom, A nano-film FTO layer is grown on the polycrystalline FTO film, characterized in that the double film structure FTO manufacturing method. The method of claim 1, A double-layer FTO manufacturing method, characterized in that to form a double-layer FTO-containing multilayer by performing an additional coating process on the upper portion of the double-layer FTO. The method according to claim 1 or 2, A method of manufacturing a double-layered FTO, wherein the base material for forming the FTO film is any one of ceramic, glass, heat-resistant plastic, and metal. The method of claim 3, wherein Forming a metal grid on the substrate; Forming a flat FTO film on the grid; A double film structure FTO manufacturing method characterized in that to form a double layer FTO-containing multilayer film by forming an FTO nanorod on the plate FTO. The method of claim 2, Metals, ceramics, polymers, transparent conductive films, oxides, semiconducting materials, insulating materials, nanoparticles, nanowires, nanoplates, nitrides, sulfides, boron compounds, carbon, nanocarbon, silicon, silica, organic compounds, organometallic compounds And coating an upper layer of the FTO nanorod layer with any one of an alkali compound, a salt, an inorganic compound, a biomaterial, and a biochemical, to form a double layer FTO-containing multilayer film. The method according to any one of claims 2 to 5, Additional coating on top of FTO nanorod layer is CVD, PVD, sputtering, atmospheric CVD, spray pyrosol, sol-gel coating, spin coating, electroplating, electroless plating, electrodeposition, ion reduction coating, spray FTO manufacturing method of a double membrane structure, characterized in that. The method of claim 1, Sn-containing precursor is formed by spray pyrosol or atmospheric pressure CVD method of any one method characterized in that the FTO manufacturing method The method according to any one of claims 1 to 7, A method of manufacturing a double film structure FTO, wherein the base material is any one of a roll type substrate, a flexible substrate, and a curved substrate. The method of claim 8, Double-layered FTO manufacturing method characterized in that the base material is any one of hard glass, flexible glass, super soft glass, glass ribbon, glass roll The method of claim 9, A method of manufacturing a double membrane structure FTO, wherein the base material is a polyimide heat-resistant plastic. A dye-sensitized film is formed by forming a TiO 2 film on a transparent electrode containing a double-layered FTO layer in which a polycrystalline FTO film is formed at the bottom and a nano-bar FTO layer is grown on the polycrystalline FTO film. Solar cell (DSSC). The polycrystalline FTO film is formed on the lower part, and the thin film silicon is formed on the transparent electrode electrode containing the double-layered FTO layer in which a nano-bar FTO layer is grown and formed on the polycrystalline FTO film, and a pn or pin junction is formed. Thin-film silicon solar cell, characterized in that.

Images