WO2012165848A2

WO2012165848A2 - Solar cell and method of preparing the same

Info

Publication number: WO2012165848A2
Application number: PCT/KR2012/004248
Authority: WO
Inventors: Kyung Eun Park
Original assignee: Lg Innotek Co., Ltd.
Priority date: 2011-05-30
Filing date: 2012-05-30
Publication date: 2012-12-06
Also published as: KR20120133175A; WO2012165848A3; KR101856212B1

Abstract

A solar cell apparatus and a method of fabricating the same are provided. The solar cell apparatus includes a substrate, a first electrode layer disposed on the substrate, a plurality of light absorption pillars disposed on the first electrode layer, a plurality of optical path changing particles disposed between the light absorption pillars, and a second electrode layer which is disposed between the light absorption pillars.

Description

SOLAR CELL AND METHOD OF PREPARING THE SAME

The embodiments relate to a solar cell apparatus and a method of fabricating the same.

Recently, as energy consumption increases, the development of solar cells capable of converting solar energy into electric energy is in progress.

In particular, copper (Cu)-indium (In)-gallium (Ga)-selenide (S) (CIGS)-based solar cells, which are PN hetero junction devices having a substrate structure including a glass substrate, a metal back electrode layer, a P-type CIGS-based light absorption layer, a high-resistance buffer layer, and an N-type window layer, or silicon-based solar cells has been widely used.

The embodiments provide a solar cell apparatus with an improved efficiency and exterior.

According to an aspect of the exemplary embodiments, there is provided a solar cell apparatus, including: a substrate; a first electrode layer disposed on the substrate; a plurality of light absorption pillars disposed on the first electrode layer; a plurality of optical path changing particles disposed between the light absorption pillars; and a second electrode layer which is disposed between the light absorption pillars.

The optical path changing particles may change wavelength of incident light.

The solar cell apparatus may also include a transparent insulating layer disposed between the light absorption pillars, wherein the optical path changing particles are disposed in the transparent insulating layer.

The optical path changing particles may be evenly distributed in the transparent insulating layer.

The transparent insulating layer may surround the light absorption pillars.

The transparent insulating layer may include a photocurable resin or a thermosetting resin.

The light absorption pillars may include silicon.

The light absorption pillars may include a group I-III-VI compound semiconductor.

The optical path changing particles may include quantum dots (QDs).

The optical path changing particles may include at least one selected from a group consisting of silica (SiO₂) and TiO₂.

According to another aspect of the exemplary embodiments, there is provided a method of fabricating a solar cell apparatus, the method including: forming a first electrode layer on a substrate; forming a plurality of light absorption pillars on the first electrode layer; forming a transparent insulating layer and a plurality of optical path changing particles between the light absorption pillars; and forming a second electrode layer on the transparent insulating layer and the light absorption pillars.

The forming the transparent insulating layer and the optical path changing particles, may include: coating a resin composition, including the optical path changing particles, between the light absorption pillars and on the first electrode layer; and curing the resin composition.

The forming the light absorption pillars, may include: forming a mask, including a plurality of through holes that expose a top surface of the first electrode layer therethrough, on the first electrode layer; and forming the light absorption pillars in the through holes, respectively.

The optical path changing particles may include QDs.

The optical path changing particles comprise at least one selected from a group consisting of silica (SiO₂) and TiO₂.

The solar cell apparatus according to an embodiment includes a plurality of light absorption pillars. The light absorption pillars may be spaced from each other. The light absorption pillars may be so small that they may be almost indiscernible to the human eye.

The solar cell apparatus according to an embodiment can transmit incident light therethrough. The light absorption pillars can absorb light and can convert the absorbed light into electric energy.

Therefore, the solar cell apparatus according to an embodiment can be used for the windows of a building. In this example, the scenery outside the building can be seen through the solar cell apparatus according to an embodiment. The solar cell apparatus according to an embodiment can generate solar power electricity in almost every part thereof.

No pattern such as transmissive and non-transmissive areas is formed in the solar cell apparatus according to an embodiment. Therefore, the solar cell apparatus according to an embodiment can have an improved exterior.

In the solar cell apparatus according to an embodiment, a plurality of optical path changing particles are provided between the light absorption pillars. Due to the optical path changing particles, the path of light incident between the light absorption pillars can be changed so that the light can be easily incident upon the light absorption pillars.

The solar cell apparatus according to an embodiment can have an improved photoelectric conversion efficiency due to the optical path changing particles and the light absorption pillars.

FIG. 1 is a cross-sectional view illustrating a solar cell apparatus according to a first embodiment;

FIG. 2 is a perspective view illustrating a plurality of light-absorption pillars according to an embodiment;

FIGS. 3 to 9 are cross-sectional views illustrating a method of fabricating a solar cell apparatus, according to a first embodiment;

FIG. 10 is a cross-sectional view illustrating a solar cell apparatus according to a second embodiment;

FIGS. 11 and 12 are cross-sectional views illustrating a method of fabricating a solar cell apparatus, according to a second embodiment;

FIG. 13 is a cross-sectional view illustrating a solar cell apparatus according to a third embodiment;

FIGS. 14 and 15 are cross-sectional views illustrating a method of fabricating a solar cell apparatus, according to a third embodiment;

FIG. 16 is a cross-sectional view illustrating a solar cell apparatus according to a fourth embodiment; and

FIGS. 17 to 19 are cross-sectional views illustrating a method of fabricating a solar cell apparatus, according to a fourth embodiment.

In the description of the embodiments, it will be understood that, when a layer (or film), a region, a pattern, or a structure is referred to as being on or under another substrate, another layer (or film), another region, another pad, or another pattern, it can be directly or indirectly over the other substrate, layer (or film), region, pad, or pattern, or one or more intervening layers may also be present. Such a position of the layer has been described with reference to the drawings. The thickness and size of each layer shown in the drawings may be exaggerated, omitted or schematically drawn for the purpose of convenience or clarity. In addition, the size of elements does not utterly reflect an actual size.

FIG. 1 is a cross-sectional view illustrating a solar cell apparatus according to a first embodiment, and FIG. 2 is a perspective view illustrating a plurality of light absorption pillars according to an embodiment.

Referring to FIGS. 1 and 2, the solar cell apparatus includes a supporting substrate 100, a first electrode layer 200, a plurality of light absorption pillars 300, a transparent insulating layer 600, a plurality of optical path changing particles 650, and a second electrode layer 700.

The supporting substrate 100 has a plate shape, and supports the first electrode layer 200, the light absorption pillars 300, and the second electrode layer 700. The supporting substrate 100 may be an insulator. The supporting substrate 100 may be a glass substrate, a plastic substrate, or a metal substrate. More specifically, the supporting substrate 100 may be a soda lime glass substrate. The supporting substrate 100 may be transparent. The supporting substrate 100 may be rigid or flexible.

The first electrode layer 200 may be disposed on the supporting substrate 100. The first electrode layer 200 may be formed on the entire surface of the supporting substrate 100. The first electrode layer 200 may include a plurality of conductive layers 201. The first electrode layer 200 may be transparent. For example, indium tin oxide (ITO), indium zinc oxide (IZO), etc., may be used as the first electrode layer 200. The first electrode layer 200 may have a thickness of about 0.5 ㎛ to about 1.5 ㎛.

The light absorption pillars 300 may be disposed on the first electrode layer 200. The light absorption pillars 300 may be electrically connected to the first electrode layer 200. For example, the light absorption pillars 300 may directly contact the first electrode layer 200.

In another example, the conductive layers 201 may be interposed between the light absorption pillars 300 and the first electrode layer 200. The conductive layers 201 may include molybdenum (Mo). The conductive layers 201 may have the same planar shape corresponding to that of the light absorption pillars 300, and may be disposed corresponding to the light absorption pillars 300, respectively. The light absorption pillars 300 may be connected to the first electrode layer 200 via the conductive layers 201, respectively.

As illustrated in FIG. 2, the light absorption pillars 300 may extend from the first electrode layer 200 to the second electrode layer 700. For example, the light absorption pillars 300 may vertically extend from the first electrode layer 200 to the second electrode layer 700. In another example, the light absorption pillars 300 may extend from the first electrode layer 200 to the second electrode layer 700 at an inclination with respect to the first electrode layer 200.

The light absorption pillars 300 have a shape that extends in one direction. For example, the light absorption pillars 300 may have a pillar shape. In another example, the light absorption pillars 300 may have a wire shape.

The light absorption pillars 300 may have a radius (R) of about 10 nm to about 100 ㎛. More specifically, the light absorption pillars 300 may have a radius (R) of about 100 nm to about 10 ㎛. The radius (R) of the light absorption pillars 300 may vary depending on the overall transmissivity and a distance (D) between the light absorption pillars 300.

The light absorption pillars 300 may be spaced from one another. The distance D between the light absorption pillars 300 may be about 100 nm to about 100 ㎛. More specifically, the distance D between the light absorption pillars 300 may be about 200 nm to about 10 ㎛. The distance D between the light absorption pillars 300 may vary depending on the radius of the light absorption pillars 300 and the overall transmissivity.

The light absorption pillars 300 may have a height (H) of about 0.5㎛ to about 1.5 ㎛.

The light absorption pillars 300 may be opaque. The light absorption pillars 300 may absorb sunlight incident thereupon. The light absorption pillars 300 may include a P-type compound semiconductor. More specifically, the light absorption pillars 300 may include a group I-III-VI compound semiconductor. For example, the light absorption pillars 300 may have a copper (Cu)-indium (In)-gallium (Ga)-selenide (Se) (Cu(In,Ga)Se2, CIGS)-based crystalline structure, a Cu-In-Se-based crystalline structure, or a Cu-Ga-Se-based crystalline structure. The light absorption pillars 300 may have an energy band gap of about 1 eV to 1.8 eV.

A plurality of buffer layers 400 may be disposed on the light absorption pillars 300, respectively, and a plurality of high-resistance buffer layers 500 may be disposed on the buffer layers 400, respectively.

The buffer layers 400 may be disposed on the light absorption pillars 300, respectively. The buffer layers 400 may directly contact the light absorption pillars 300, respectively. The buffer layers 400 may have a planar shape corresponding to that of the light absorption pillars 300. The buffer layers 400 may be disposed corresponding to the light absorption pillars 300, respectively. The buffer layers 400 may include cadmium sulfide. The buffer layers 400 may have an energy band gap of about 1.9 eV to about 2.3 eV. The buffer layers 400 may have a thickness of about 30 nm to about 70 nm.

The high-resistance buffer layers 500 may be disposed on the buffer layers 400, respectively. The high-resistance buffer layers 500 may directly contact the buffer layers 400, respectively. The high-resistance buffer layers 500 may have a planar shape corresponding to that of the light absorption pillars 300. The high-resistance buffer layers 500 may be disposed corresponding to the light absorption pillars 300, respectively. The high-resistance buffer layers 500 may include zinc oxide not doped with impurities. The high-resistance buffer layers 500 may have an energy band gap of about 3.1 eV to about 3.3 eV. The high-resistance buffer layers 500 may have a thickness of about 50 nm to about 100 nm.

The transparent insulating layer 600 may be disposed between the light absorption pillars 300. The transparent insulating layer 600 may be disposed on the first electrode layer 200. The transparent insulating layer 600 may surround the light absorption pillars 300. More specifically, the transparent insulating layer 600 may directly contact the side surfaces of the light absorption pillars 300.

The transparent insulating layer 600 may also surround the conductive layers 201. The transparent insulating layer 600 may also surround the buffer layers 400 and the high-resistance buffer layers 500.

The transparent insulating layer 600 may be a transparent insulator. A transparent polymer such as an acrylic resin, a silicon resin, an epoxy resin, etc., may be used as the transparent insulating layer 600. A photocurable resin may be used as the transparent insulating layer 600.

The top surface of the transparent insulating layer 600 may be on a level with or below the top surfaces of the high-resistance buffer layers 500. Accordingly, the top surfaces of the high-resistance buffer layers 500 may be exposed above the top surface of the transparent insulating layer 600.

The top surface of the transparent insulating layer 600 may be below the top surfaces of the light absorption pillars 300. Accordingly, the light absorption pillars 300 may protrude beyond the top surface of the transparent insulating layer 600.

The optical path changing particles 650 may be disposed between the light absorption pillars 300. More specifically, the optical path changing particles 650 may be disposed in the transparent insulating layer 600. The optical path changing particles 650 may be uniformly distributed in the transparent insulating layer 600.

The optical path changing particles 650 may change the path of incident light. For example, the optical path changing particles 650 may change the path of incident light such that the incident light may travel toward the sides of the light absorption pillars 300. That is, due to the optical path changing particles 650, light incident between the light absorption pillars 300 may be effectively incident upon the sides of the light absorption pillars 300, instead of being transmitted through the solar cell apparatus according to the first embodiment.

For example, the optical path changing particles 650 may change the path of incident light by scattering. In another example, the optical path changing particles 650 may be excited by incident light, and may thus emit light in random directions, thereby substantially changing the path of light.

The optical path changing particles 650 may have various diameters. For example, the optical path changing particles 650 may have a diameter of about several nanometers to several micrometers. That is, the optical path changing particles 650 may be nanoparticles or microparticles. For example, the optical path changing particles 650 may be transparent beads. In another example, the optical path changing particles 650 may be opaque metal particles. The optical path changing particles 650 may have various shapes. For example, the optical path changing particles 650 may have a spherical shape, a pillar shape, a polyhedral shape, a cone shape, etc.

The optical path changing particles 650 may convert the wavelength of incident light. That is, the optical path changing particles 650 may be wavelength-converting particles. The optical path changing particles 650 may change the color of incident light. The optical path changing particles 650 may be phosphors or quantum dots (QDs).

More specifically, the optical path changing particles 650 may be QDs.

A QD may include a core nano crystal and a shell nano crystal surrounding the core nano crystal. The QD may also include an organic ligand coupled to the shell nano crystal. The QD may also include an organic coating layer surrounding to the shell nano crystal.

The shell nano crystal may have a two-layered structure. The shell nano crystal is formed on the surface of the core nano crystal. The QD may convert the wavelength of light incident into the core nano crystal into light having a long wavelength through the shell nano crystal forming a shell layer to improve light efficiency.

The QD may be formed of at least one material of a group II compound semiconductor, a group III compound semiconductor, a group V compound semiconductor, and a group VI compound semiconductor. More specifically, the core nano crystal may include CdSe, InGaP, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe, or HgS. The shell nano crystal may also be formed of CuZnS, CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe, or HgS. The QD may have a diameter of about 1 nm to about 10 nm.

The wavelength of the light emitted from the QD may be adjusted according to the size of the QD or the molar ratio of a molecular cluster compound and a nano particle precursor in a synthesis process. The organic ligand may include at least one of pyridine, mercapto alcohol, thiol, phosphine, and phosphine oxide. The organic ligand may stabilize the unstable QD after the synthesis process. After the synthesis process, a dangling bond is formed outside the QD. Thus, the QD may be unstable due to the dangling bond. However, one end of the organic ligand may be in a non-bonded state, and the non-bonded one end of the organic ligand may be bonded to the dangling bond to stabilize the QD.

Specifically, when the QD has a radius less than a Bohr radius of an exciton constituted by an electron and hole, which are excited by light and electricity, a quantum confinement effect may occur. Thus, the QD has a discrete energy level to change the intensity of an energy gap. In addition, a charge may be limited within the QD to provide high light emitting efficiency.

The emission wavelength of the QD, unlike that of a general fluorescent dye, may change according to the particle size thereof. That is, as the particle size decreases, the QD may emit light having a shorter wavelength. Thus, the particle size may be adjusted to emit visible light having a desired wavelength. Also, since the QD has an extinction coefficient greater by about 100 times to about 1,000 times than that of the general fluorescent dye and quantum yield greater than that of the general fluorescent dye, the QD may emit very intense light.

The QD may be synthesized by a chemical wet etching process. The chemical wet etching process is a process in which a precursor material is immersed into an organic solvent to grow particles. Thus, the QD may be synthesized through the chemical wet etching process.

The optical path changing particles 650 are not restricted to the embodiment set forth herein. That is, the optical path changing particles 650 may include various materials such as silica (SiO₂),TiO₂, etc.

The second electrode layer 700 may be disposed on the light absorption pillars 300. More specifically, the second electrode layer 700 may be disposed on the high-resistance buffer layers 500. The second electrode layer 700 may also be disposed on the transparent insulating layer 600. The second electrode layer 700 may surround the light absorption pillars 300.

The second electrode layer 700 may be connected to the light absorption pillars 300. More specifically, the second electrode layer 700 may be connected to each of the light absorption pillars 300 via the high-resistance buffer layers 500 and the buffer layers 400. That is, the second electrode layer 700 may directly contact the high-resistance buffer layers 500.

In a case in which the high-resistance buffer layers 500 protrude beyond the transparent insulating layer 600, the high-resistance buffer layers 500 may be inserted into the second electrode layer 700. In a case in which the buffer layers 400 protrude beyond the transparent insulating layer 600, the buffer layers 400 may also be inserted into the second electrode layer 700.

In a case in which the light absorption pillars 300 protrude beyond the transparent insulating layer 600, the light absorption pillars 300 may also be inserted into the second electrode layer 700. The second electrode layer 700 may be disposed on the light absorption pillars 300 and on the sides of the light absorption pillars 300. Accordingly, the second electrode layer 700 may directly contact the sides of the light absorption pillars 300.

The second electrode layer 700 is transparent. The second electrode layer 700 includes the conductive layers 201. Aluminum (Al)-doped zinc oxide (AZO), ITO, IZO, etc., may be used as the second electrode layer 700. The second electrode layer 700 may have a thickness of about 1 ㎛ to about 1.5 ㎛.

The light absorption pillars 300 may have such a small diameter that they may be almost indiscernible to the human eye. The first electrode layer 200 and the second electrode layer 700 may be transparent. Accordingly, light may transmit through most parts of the first electrode layer 200 and the second electrode layer 700 except where the light absorption pillars 300 are formed.

The solar cell apparatus according to the first embodiment may transmit light through almost every part thereof. Due to the light absorption pillars 300, the solar cell apparatus according to the first embodiment may absorb light, and may convert the absorbed light into electric energy.

For example, the solar cell apparatus according to the first embodiment may be used for the windows of a building. In this example, the scenery outside the building may be seen through the solar cell apparatus according to the first embodiment. The solar cell apparatus according to the first embodiment may generate solar power electricity in almost every part thereof.

No pattern such as transmission and non-transmission areas may be formed in the solar cell apparatus according to the first embodiment. Since the optical path changing particles 650 may be able to change the wavelength of incident light, the solar cell apparatus according to the first embodiment may have a color, and may thus have an improved exterior.

The optical path changing particles 650 are arranged between the light absorption pillars 300. Accordingly, the path of light transmitted through the solar cell apparatus according to the first embodiment, and particularly, between the light absorption pillars 300, may be changed by the optical path changing particles 650, and may thus be easily incident upon the light absorption pillars 300.

Therefore, the solar cell apparatus according to the first embodiment may have an improved photoelectric conversion efficiency due to the optical path changing particles 650 and the light absorption pillars 300.

FIGS. 3 to 9 are cross-sectional diagrams illustrating a method of fabricating a solar cell apparatus, according to a first embodiment. The method of fabricating a solar cell apparatus, according to the first embodiment will hereinafter be described, taking the solar cell apparatus according to the first embodiment as an example. The description of the solar cell apparatus according to the first embodiment may substantially apply to the method of fabricating a solar cell apparatus, according to the first embodiment.

Referring to FIG. 3, a first electrode layer 200 is formed on a support substrate 100. The first electrode layer 200 may be formed by depositing a transparent conductive material such as ITO, IZO, etc., on the top surface of the support substrate 100 through sputtering.

Referring to FIG. 4, a mask layer 10 is formed on the first electrode layer 200. The mask layer 10 may be formed by imprinting or photolithography. The mask layer 10 may include a plurality of through holes 11 which expose the top surface of the first electrode layer 200 therethrough. The diameter of and the distance between the through holes 11 may vary depending on the diameter of and the distance between a plurality of light absorption pillars 300 to be formed.

Referring to FIG. 5, a metal such as molybdenum (Mo), etc., is deposited on the mask layer 10 and inside the through holes 11. Accordingly, a plurality of conductive layers 201 are formed in the through holes 11, respectively.

A plurality of light absorption pillars 300 are formed in the through holes 11, respectively. The light absorption pillars 300 may be formed by sputtering or vaporization.

For example, a plurality of CIGS-based light absorption pillars may be formed as the light absorption pillars 300 by vaporizing Cu, In, Ga, and Se at the same time or separately. In another example, the light absorption pillars 300 may be formed by forming a metallic precursor layer and performing selenization on the metallic precursor layer.

More specifically, in the latter method of forming the light absorption pillars 300, a metallic precursor layer is formed on the mask layer 10 and inside the through holes 11 by a sputtering operation using Cu, In, and Ga targets.

The metallic precursor layer may be transformed into a CIGS-based compound semiconductor by a selenization operation.

Alternatively, the sputtering operation and the selenization operation may be performed at the same time.

Alternatively, a CIS-based compound semiconductor or a CIG-based compound semiconductor may be formed by a sputtering operation only using Cu and In targets or Cu and Ga targets and a selenization operation.

Accordingly, a group I-III-VI compound semiconductor may be deposited inside the through holes 11, thereby forming the light absorption pillars 300.

A plurality of buffer layers 400 are formed on the light absorption pillars 300, respectively. The buffer layers 400 may be formed by chemical bath deposition (CBD). For example, after the formation of the light absorption pillars 300, the light absorption pillars 300 and the mask layer 10 may be immersed in a solution containing materials to form cadmium sulfide. As a result, the buffer layers 400, containing cadmium sulfide, may be formed on the light absorption pillars 300, respectively.

A plurality of high-resistance buffer layers 500 are formed on the buffer layers 400, respectively. The high-resistance buffer layers 500 may be formed by a sputtering using a zinc oxide target not doped with impurities. Accordingly, zinc oxide may be deposited on the mask layer 10 and inside the through holes 11, thereby forming the high-resistance buffer layers 500 in the through holes 11, respectively.

The mask layer 10 is removed. When the mask layer 10 is removed, the metal, the group I-III-VI compound semiconductor, the cadmium sulfide, and the zinc oxide that are all deposited on the mask layer 10 may be automatically removed along with the mask layer 10.

Referring to FIG. 7, a resin composition, which is mixed with a plurality of optical path changing particles 650, is coated on the first electrode layer 200. The optical path changing particles 650 may be evenly distributed in the resin composition.

The resin composition may cover the light absorption pillars 300. The resin composition, in which the optical path changing particles 650 are distributed, may be coated on the first electrode layer 200 by spin coating, spray coating, or slit coating. The resin composition may include a thermosetting resin and/or a photocurable resin.

The resin composition coated on the first electrode layer 200 may be cured by light and/or heat. Accordingly, a preliminary transparent insulating layer 601 is formed on the first electrode layer 200. The preliminary transparent insulating layer 601 may cover the light absorption pillars 300. More specifically, the preliminary transparent insulating layer 601 may cover the high-resistance buffer layers 500. Accordingly, the top surfaces of the high-resistance buffer layers 500 may be located inside the preliminary transparent insulating layer 601.

Referring to FIG. 8, a transparent insulating layer 600 is formed by partially etching away the preliminary transparent insulating layer 601. Accordingly, the top surfaces of the high-resistance buffer layers 500 may be exposed above the transparent insulating layer 600. The buffer layers 400 and the light absorption pillars 300 may also be exposed above the transparent insulating layer 600 according to the degree to which the preliminary transparent insulating layer 601 is etched away.

Alternatively to the example illustrated in FIGS. 7 and 8, the resin composition may be coated on the first electrode layer 200 such that the top surfaces of the high-resistance buffer layers 500 may be exposed. In this example, the etching operation as performed in the example illustrated in FIG. 8 may be unnecessary.

Referring to FIG. 9, a second electrode layer 700 is formed by depositing a transparent conductive material on the transparent insulating layer 600 and the high-resistance buffer layers 500. For example, the second electrode layer 700 may be formed by depositing a transparent conductive material such as aluminum-doped zinc oxide (AZO), ITO, IZO, etc., through sputtering.

According to the method of fabricating a solar cell apparatus, according to the first embodiment, it is possible to facilitate the fabrication of a solar cell apparatus with an improved photoelectric conversion efficiency.

FIG. 10 is a cross-sectional view illustrating a solar cell apparatus according to a second embodiment, and FIGS. 11 and 12 are cross-sectional views illustrating a method of fabricating a solar cell apparatus, according to a second embodiment. FIG. 13 is a cross-sectional view illustrating a solar cell apparatus according to a third embodiment, and FIGS. 14 and 15 are cross-sectional views illustrating a method of fabricating a solar cell apparatus, according to a third embodiment. The descriptions of the solar cell apparatus according to the first embodiment and the method of fabricating a solar cell apparatus, according to the first embodiment may substantially apply to the solar cell apparatuses according to the second and third embodiments and the methods of fabricating a solar cell apparatus, according to the second and third embodiments.

Referring to FIG. 10, a buffer layer 401 is disposed on a transparent insulating layer 600 and a plurality of light absorption pillars 300. More specifically, the buffer layer 401 may cover the transparent insulating layer 600 and the light absorption pillars 300. That is, the buffer layer 401 may be formed on the top surface of the transparent insulating layer 600. The buffer layer 401 may be coated not only on the top surface of the transparent insulating layer 600 but also on the top surfaces of the light absorption pillars 300.

A method of fabricating the solar cell apparatus according to the second embodiment will hereinafter be described with reference to FIGS. 11 and 12.

Referring to FIG. 11, the light absorption pillars 300 are formed, and then, the transparent insulating layer 600 is formed. That is, the light absorption pillars 300 are formed by using a mask layer, the mask layer is removed after the formation of the light absorption pillars 300, and the transparent insulating layer 600 is formed.

The buffer layer 401 and then a high-resistance buffer layer 501 are formed by performing a deposition operation on the transparent insulating layer 600 and on the light absorption pillars 300.

Referring to FIG. 12, a second electrode layer 700 is formed by depositing a transparent conductive material on the high-resistance buffer layer 501.

The buffer layer 401 and the high-resistance buffer layer 501 may be formed on the entire transparent insulating layer 600 and on the entire light absorption pillars 300.

Referring to FIG. 13, a plurality of buffer layers 400 are disposed on a plurality of light absorption pillars 300, respectively. A high-resistance buffer layer 501 is disposed on a transparent insulating layer 600 and on the buffer layers 400. That is, the high-resistance buffer layer 501 may directly contact the top surface of the transparent insulating layer 600 and may cover the buffer layers 400.

A method of fabricating the solar cell apparatus according to the third embodiment will hereinafter be described with reference to FIGS. 14 and 15.

Referring to FIG. 14, a plurality of light absorption pillars 300 and a plurality of buffer layers 400 are formed, and then, a transparent insulating layer 600 is formed. That is, the light absorption pillars 300 and the buffer layers 400 are formed by using a mask layer 10, the mask layer 10 is removed after the formation of the light absorption pillars 300, and the transparent insulating layer 600 is formed.

A high-resistance buffer layer 501 is formed on the transparent insulating layer 600 and the buffer layers 400 by deposition.

Referring to FIG. 15, a second electrode layer 700 is formed by depositing a transparent conductive material on the high-resistance buffer layer 501.

The high-resistance buffer layer 501 may be formed on the entire transparent insulating layer 600 and on the entire buffer layers 400. The solar cell apparatus according to the third embodiment may have an improved exterior and performance due to a plurality of optical path changing particles 650.

FIG. 16 is a cross-sectional view illustrating a solar cell apparatus according to a fourth embodiment, and FIGS. 17 to 19 are cross-sectional views illustrating a method of fabricating a solar cell apparatus, according to a fourth embodiment. The descriptions of the solar cell apparatuses according to the previous embodiments and the methods of fabricating a solar cell apparatus, according to the previous embodiments may substantially apply to the solar cell apparatus according to the fourth and third embodiments and the method of fabricating a solar cell apparatus, according to the fourth embodiment.

Referring to FIG. 16, a plurality of light absorption pillars 800 may include silicon. More specifically, the light absorption pillars 800 may be generally formed of silicon. That is, the light absorption pillars 800 may have a silicon-based P-N junction structure or a silicon-based P-I-N junction structure. The light absorption pillars 800 may include a plurality of first conductivity type portions 810, respectively, a plurality of second conductivity type portions 820, respectively, and a plurality of third conductivity type portions 830, respectively.

The first conductivity type portions 810 are disposed on a first electrode layer 200. The first conductivity type portions 810 may be directly connected to the first electrode layer 200 or may be connected to the first electrode layer 200 via a plurality of conductive layers 201. The first conductivity type portions 810 have a first conductivity type. For example, the first conductivity type may be a P type. More specifically, the first conductivity type portions 810 may be doped with P-type impurities. For example, the first conductivity type portions 810 may include silicon doped with P-type impurities such as Al, Ga, In, etc.

The second conductivity type portions 820 are disposed on the first conductivity type portions 810. The second conductivity type portions 820 may be formed in one body with the first conductivity type portions 810. The second conductivity type portions 820 may have an I type. That is, the second conductivity type portions 820 may not be doped with impurities. For example, the second conductivity type portions 820 may include silicon not doped with impurities.

The third conductivity type portions 830 are disposed above the first conductivity type portions 810. The third conductivity type portions 830 are disposed on the second conductivity type portions 820. The third conductivity type portions 830 may directly contact the second conductivity type portions 820. The third conductivity type portions 830 may have a second conductivity type. For example, the second conductivity type may be an N-type. More specifically, the third conductivity type portions 830 may be doped with N-type impurities. For example, the third conductivity type portions 830 may include silicon doped with N-type impurities such as phosphorous (P), nitrogen (N), asbestos (As), etc.

The light absorption pillars 800 are connected to the second electrode layer 700. More specifically, the light absorption pillars 800 may be directly connected to the second electrode layer 700. That is, the top surfaces of the light absorption pillars 800 may directly contact the second electrode layer 700. The third conductivity type portions 830 may be directly connected to the second electrode layer 700.

A method of fabricating the solar cell apparatus according to the fourth embodiment will hereinafter be described with reference to FIGS. 17 to 19.

Referring to FIG. 17, a first electrode layer 200 is formed on a support substrate 100.

A mask layer 10 having a plurality of through holes is formed on the first electrode layer 200.

Silicon doped with P-type impurities, silicon not doped with impurities, and silicon doped with N-type impurities are sequentially deposited on the top surface of the mask layer 10 and inside the through holes.

Alternatively, Al and then silicon doped with P-type impurities may be deposited on the top surface of the mask layer 10 and inside the through holes.

Referring to FIG. 18, the mask layer 10 is removed, and a transparent insulating layer 600 is formed between the light absorption pillars 800. A transparent conductive material is deposited on the transparent insulating layer 600 and the light absorption pillars 800, and a second electrode layer 700 is formed.

The solar cell apparatus according to the fourth embodiment may transmit light through almost every part thereof due to the light absorption pillars 800, which contain silicon. The solar cell apparatus according to the fourth embodiment may have an improved photoelectric conversion efficiency and exterior due to a plurality of optical path changing particles 650.

The foregoing exemplary embodiments and advantages are merely exemplary and are not to be construed as limiting. The present teaching can be readily applied to other types of apparatuses. Also, the description of the exemplary embodiments is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.

Claims

A solar cell apparatus, comprising:

a substrate;

a first electrode layer disposed on the substrate;

a plurality of light absorption pillars disposed on the first electrode layer;

a plurality of optical path changing particles disposed between the light absorption pillars; and

a second electrode layer which is disposed between the light absorption pillars.
The solar cell apparatus of claim 1, wherein the optical path changing particles change wavelength of incident light.
The solar cell apparatus of claim 1, further comprising:

a transparent insulating layer disposed between the light absorption pillars,

wherein the optical path changing particles are disposed in the transparent insulating layer.
The solar cell apparatus of claim 3, wherein the optical path changing particles are evenly distributed in the transparent insulating layer.
The solar cell apparatus of claim 3, wherein the transparent insulating layer surrounds the light absorption pillars.
The solar cell apparatus of claim 3, wherein the transparent insulating layer comprises a photocurable resin or a thermosetting resin.
The solar cell apparatus of claim 1, wherein the light absorption pillars comprise silicon.
The solar cell apparatus of claim 1, wherein the light absorption pillars comprise a group I-III-VI compound semiconductor.
The solar cell apparatus of claim 1, wherein the optical path changing particles comprise quantum dots (QDs).
The solar cell apparatus of claim 1, wherein the optical path changing particles comprise at least one selected from a group consisting of silica (SiO₂) and TiO₂.
A method of fabricating a solar cell apparatus, the method comprising:

forming a first electrode layer on a substrate;

forming a plurality of light absorption pillars on the first electrode layer;

forming a transparent insulating layer and a plurality of optical path changing particles between the light absorption pillars; and

forming a second electrode layer on the transparent insulating layer and the light absorption pillars.
The method of claim 11, wherein the forming the transparent insulating layer and the optical path changing particles, comprises:

coating a resin composition, including the optical path changing particles, between the light absorption pillars and on the first electrode layer; and

curing the resin composition.
The method of claim 11, wherein the forming the light absorption pillars, comprises:

forming a mask, including a plurality of through holes that expose a top surface of the first electrode layer therethrough, on the first electrode layer; and

forming the light absorption pillars in the through holes, respectively.
The method of claim 11, wherein the optical path changing particles comprise quantum dots (QDs).
The method of claim 11, wherein the optical path changing particles comprise at least one selected from a group consisting of silica (SiO₂) and TiO₂.