Cadmium telluride power generation glass with tellurium-zinc-cadmium and zinc telluride composite back contact layer and preparation method of cadmium telluride power generation glass

Abstract

The invention relates to the technical field of preparation of cadmium telluride power generation glass, in particular to cadmium telluride power generation glass with a cadmium zinc telluride and zinc telluride composite back contact layer and a preparation method of the cadmium telluride power generation glass. The provided power generation glass comprises a substrate, and a TCO film layer, a window layer, an absorption layer, a composite back contact layer and a back electrode which are sequentially arranged at the upper part of the substrate. The composite back contact layer includes a first back contact layer and a second back contact layer. The preparation method comprises the following steps: providing a substrate, and growing the TCO film layer, the window layer, the absorption layer, the first back contact layer, the second back contact layer and the back electrode on the substrate to obtain the power generation glass. Depositing a first back contact layer on the absorption layer by adopting discontinuous film layer deposition, and then annealing; depositing a second back contact layer on the first back contact layer to obtain a second structure, performing heat treatment on the second structure, and depositing a back electrode to obtain the power generation glass with excellent performance. The problems of uncontrollable copper diffusion and poor interface stability in cadmium telluride power generation glass in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of cadmium telluride power generation glass preparation, in particular to a cadmium telluride power generation glass having a cadmium zinc telluride and zinc telluride composite back contact layer and a preparation method thereof. Background Art

[0002] Cadmium telluride solar cells / CdTe solar cell glass are a highly efficient, low-cost photovoltaic technology. In the fabrication of CdTe solar cell glass, the choice and performance of the back contact layer directly impact the cell's conversion efficiency and stability. However, conventional back contact technology faces two major challenges: first, the high work function of CdTe leads to the formation of a Schottky barrier with the metal electrode; second, the severe recombination at the back contact interface of existing CdTe solar cell glass affects the glass's carrier collection efficiency.

[0003] In order to overcome the above-mentioned defects, the solutions commonly used in the prior art are: (1) using a copper-doped zinc telluride film as a buffer layer; (2) using cuprous telluride as a transition layer; and (3) using graphite slurry as a composite contact material.

[0004] However, the above method uses ZnTe doped with Cu back contact, which may cause problems such as band mismatch. For example, there will be a 0.3eV conduction band offset at the ZnTe / CdTe interface, which will lead to an electron barrier. Secondly, the diffusion coefficient of Cu in CdTe is: ~10 at 300K. -12 cm 2 / s (SIMs analysis), resulting in an average annual degradation of battery efficiency of 0.5% to 1%. A single ZnTe back contact film layer relies on controlled Cu doping concentration (1% to 5%), which cannot effectively avoid copper diffusion problems. Furthermore, the process window is narrow, with doping uniformity required to be ±0.3%, placing extremely high demands on film thickness and Cu doping level.

[0005] Therefore, the above methods have obvious and difficult-to-solve defects: uncontrollable copper diffusion and poor interface stability. Summary of the Invention

[0006] In order to solve the technical problems of uncontrollable copper diffusion and poor interface stability in cadmium telluride power generation glass in the prior art, the present invention aims to provide a cadmium telluride power generation glass with excellent performance and a preparation method thereof, which can eliminate the potential barrier between CdTe and the back electrode and improve the electrical properties of the power generation glass.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a cadmium telluride power generation glass having a composite back contact layer of cadmium zinc telluride and zinc telluride, wherein the power generation glass comprises a substrate and a TCO film layer, a window layer, an absorption layer, a composite back contact layer and a back electrode sequentially arranged on the upper portion of the substrate.

[0009] Furthermore, the composite back contact layer includes a first back contact layer disposed on the absorber layer and a second back contact layer disposed on the first contact layer.

[0010] Furthermore, the first back contact layer is a metal-doped CdZnTe compound material; and the second back contact layer is a metal-doped ZnTe compound material.

[0011] Furthermore, the CdZnTe compound material includes CdTe and ZnTe in a molar ratio of 6:4.

[0012] Furthermore, the metal doping material of the CdZnTe compound material is one or more of Ag, Cu, Hg, and Au.

[0013] Furthermore, the doping ratio of the metal doping material in the CdZnTe compound material is 100 ppm to 1 wt%.

[0014] Furthermore, the metal doping material of the ZnTe compound material is one or more of Ag, Cu, Hg, and Au.

[0015] Furthermore, the metal doping material of the ZnTe compound material is co-doped with Ag and Cu, the doping ratio of Ag is 100 ppm to 1% wt, and the doping ratio of Cu is 100 ppm to 3% wt.

[0016] In a second aspect, the present invention further provides a method for preparing the cadmium telluride power generation glass having the composite back contact layer of cadmium zinc telluride and zinc telluride as described above, the preparation method comprising the following steps:

[0017] Providing a substrate, and sequentially growing a TCO film layer, a window layer, and an absorption layer on the substrate to obtain a first structure;

[0018] Depositing a first back contact layer and a second back contact layer in sequence on the absorption layer of the first structure to obtain a second structure;

[0019] The second structure is heat-treated, and then a back electrode is deposited on the second back contact layer to obtain a power generation glass. Furthermore, the deposition of the first back contact layer and the second back contact layer includes depositing the first back contact layer on the absorber layer using discontinuous film deposition, followed by annealing, and then depositing the second back contact layer on the first back contact layer.

[0020] The beneficial effects of the present invention are:

[0021] 1. The present invention provides a cadmium telluride power generation glass having a composite back contact layer of cadmium zinc telluride and zinc telluride. By providing a special composite back contact layer in the cadmium telluride power generation glass, this composite back contact layer can form good energy band alignment, reduce energy band mutation (potential barrier) at the interface, thereby promoting the transmission of holes (majority carriers in p-type CdTe) to the back electrode, effectively reducing interfacial recombination, and effectively improving the ohmic contact with the back electrode, thereby increasing the current density and fill factor of the cadmium telluride power generation glass, and effectively improving the conversion efficiency of the cadmium telluride power generation glass. At the same time, it can also eliminate the barrier between CdTe and the back electrode, resulting in excellent photoelectric performance of the cadmium telluride power generation glass. This effectively solves the problems of uncontrollable copper diffusion and poor interface stability in cadmium telluride power generation glass in the prior art.

[0022] 2. The present invention provides a method for preparing cadmium telluride (CdZnTe)-zinc telluride composite back contact layer. The method comprises depositing a first back contact layer on an absorber layer using discontinuous film deposition, followed by annealing to form island-like nanodots in the first back contact layer. A second back contact layer is then deposited on the first back contact layer. The nanodots in the first back contact layer enhance the passage of shortwave light, prompting the second back contact layer to absorb more shortwave light. Simultaneously, the second back contact layer ensures efficient hole transport, thereby reducing leakage current. The first and second back contact layers interact to synergistically improve Jsc and FF. This method results in excellent photoelectric performance for the CdTe glass produced, resolving the issues of uncontrollable copper diffusion and poor interface stability in prior art CdTe glass. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic structural diagram of a cadmium telluride power generation glass provided by the present invention having a composite back contact layer of cadmium zinc telluride and zinc telluride.

[0024] Figure 2 Schematic diagram of the mechanism of a cadmium telluride power generation glass with a composite back contact layer of cadmium zinc telluride and zinc telluride provided by the present invention Figure 1 .

[0025] Figure 3 Schematic diagram of the mechanism of a cadmium telluride power generation glass with a composite back contact layer of cadmium zinc telluride and zinc telluride provided by the present invention Figure 2 . DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0027] Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0028] First, an embodiment of the present invention provides a cadmium telluride power generation glass having a cadmium zinc telluride and zinc telluride composite back contact layer, the power generation glass comprising a substrate and a TCO film layer, a window layer, an absorption layer, a composite back contact layer and a back electrode sequentially arranged on the substrate.

[0029] It is understood that the CdTe power generation glass provided by the embodiments of the present invention, which has a composite back contact layer of CdZnTe and ZnTe, has a special composite back contact layer provided in the CdTe power generation glass. This composite back contact layer can form good energy band alignment, reduce energy band mutation (potential barrier) at the interface, thereby promoting the transmission of holes (majority carriers in p-type CdTe) to the back electrode, effectively reducing interfacial recombination, and effectively improving the ohmic contact with the back electrode, thereby improving the current density and fill factor of the CdTe power generation glass, and effectively improving the conversion efficiency of the CdTe power generation glass. At the same time, it can also eliminate the barrier between CdTe and the back electrode, resulting in excellent photoelectric performance of the CdTe power generation glass. This effectively solves the problems of uncontrollable copper diffusion and poor interface stability in CdTe power generation glass in the prior art.

[0030] In some embodiments of the present invention, the composite back contact layer includes a first back contact layer disposed on the absorber layer and a second back contact layer disposed on the first contact layer.

[0031] In some embodiments of the present invention, the first back contact layer is a metal-doped CdZnTe compound material; the second back contact layer is a metal-doped ZnTe compound material.

[0032] In some embodiments of the present invention, the CdZnTe compound material includes CdTe and ZnTe in a molar ratio of 6:4.

[0033] In some embodiments of the present invention, the CdTe and ZnTe of the CdZnTe compound material are preferably made of 5N purity polycrystalline targets.

[0034] In some embodiments of the present invention, the CdZnTe compound material uses CdTe and ZnTe polycrystalline targets, which are mixed at a ratio of CdTe:ZnTe=6:4 and are doped with 200 ppm Ag.

[0035] The production steps of CdTe and ZnTe polycrystalline targets are vacuum packaging, melt homogenization, and directional crystallization.

[0036] In some embodiments of the present invention, vacuum packaging includes sealing the raw material in a carbonized quartz crucible and evacuating the crucible to 10 -5 mbar, avoid oxidation.

[0037] In some embodiments of the present invention, melt homogenization includes slowly heating to 1100-1200° C. (higher than the melting point of CdZnTe, approximately 1092° C.), and stirring at a constant temperature for 10-24 hours to homogenize the melt.

[0038] In some embodiments of the present invention, directional crystallization includes slowly cooling at a rate of 0.2-1 mm / h to control the crystal growth direction by temperature gradient.

[0039] In some embodiments of the present invention, the metal doping material of the CdZnTe compound material is one or more of Ag, Cu, Hg, and Au.

[0040] In some embodiments of the present invention, the doping ratio of the metal doping material in the CdZnTe compound material is 100 ppm to 1 wt %.

[0041] In some embodiments of the present invention, the thickness of the first back contact layer is 5-30 nm.

[0042] In some embodiments of the present invention, the metal doping material of the ZnTe compound material is one or more of Ag, Cu, Hg, and Au.

[0043] In some embodiments of the present invention, the metal doping material of the ZnTe compound material is preferably co-doped with Ag and Cu, with the doping ratio of Ag being 100 ppm to 1% wt and the doping ratio of Cu being 100 ppm to 3% wt.

[0044] In some embodiments of the present invention, the second back contact layer is a metal-doped ZnTe compound material, and the ZnTe is nanoparticles with a size less than 10 nm.

[0045] ZnTe nanoparticles with a size of less than 10nm can selectively fill the Te vacancies at the grain boundaries of the first back contact layer CdZnTe, reducing the deep energy level defect density by 50%, and further realizing the coordinated regulation of the first contact layer and the second contact layer.

[0046] In some embodiments of the present invention, the first back contact layer is preferably deposited by discontinuous film layers.

[0047] In some embodiments of the present invention, the second back contact layer is preferably formed by low-temperature deposition using magnetron sputtering.

[0048] In some embodiments of the present application, the second back contact layer has a thickness of less than 5-30 nm.

[0049] In some embodiments of the present application, the TCO film layer can realize light transmission and collect holes, and preferably uses SnO2:F (FTO) or In2O3:Sn (ITO).

[0050] In some embodiments of the present application, the window layer preferably uses a CdSe window layer, which is a wide band gap material (Eg≈1.7eV), and can further reduce interface recombination.

[0051] In some embodiments of the present application, the window layer has a thickness of generally 50-300 nm, and the deposition method includes, but is not limited to, near-space sublimation, magnetron sputtering, and vapor transport deposition.

[0052] In some embodiments of the present application, the absorption layer preferably uses a CdTe absorption layer, which is a main photovoltaic material (Eg≈1.5eV).

[0053] In some embodiments of the present application, the absorption layer has a thickness of generally 2-5 μm, and the deposition method includes, but is not limited to, near-space sublimation, magnetron sputtering, and vapor transport deposition.

[0054] In some embodiments of the present application, the back electrode is preferably Mo, Al, or Ag.

[0055] In some embodiments of the present application, the thickness is 100-200 nm, and the main function is to collect and conduct charges.

[0056] It can be further understood that the CdZnTe (Zn gradient adjustment band gap 1.45-1.7eV) of the first back contact layer can absorb visible light, and the ZnTe (Eg≈2.26eV) of the second back contact layer can enhance the utilization of short-wavelength light (300-500 nm), and can realize full-spectrum coverage.

[0057] The ZnTe thin film of the second back contact layer covers the surface of the CdZnTe of the first back contact layer, and can reduce the surface recombination rate (SRV) from 10 5 cm / s to 10 3 cm / s through chemical bonding (Zn-Te) and field effect passivation (internal built-in electric field).

[0058] Specifically, first, by arranging a composite back contact layer in the cadmium telluride power glass, the band matching and carrier transport can be adjusted.

[0059] Please refer to Figure 3The first back contact layer, CdZnTe, is doped with metallic Ag. Adjusting the Ag content modifies the band gap, resulting in a slightly wider band gap than CdTe (approximately 1.45-1.5 eV). As a buffer layer, the first back contact layer, CdZnTe, achieves good band alignment with the CdTe absorber layer, reducing band shifts (potential barriers) at the interface. This promotes the transport of holes (the majority carriers in p-type CdTe) to the back electrode and reduces interfacial recombination.

[0060] The ZnTe layer in the second back contact layer is a p-type semiconductor with a band gap of approximately 2.26eV, matching the p-type characteristics of CdTe. ZnTe's high work function (approximately 5.7eV) reduces the contact barrier between the back electrode metal (such as Mo, Al, Au, Ni, etc.) and CdTe, forming an ohmic contact and reducing contact resistance.

[0061] Secondly, by providing a composite back contact layer in the cadmium telluride solar cell, metal diffusion and defect passivation can be suppressed. Traditional back contacts of CdTe cells often use metals (such as Cu-doped Au or graphite), but metal atoms (such as Cu) easily diffuse into the CdTe absorption layer, resulting in deep energy level defects and triggering light-induced degradation.

[0062] A composite back contact layer (CdZnTe / ZnTe composite layer) is introduced. By introducing the CdZnTe compound material: Ag and ZnTe: Ag: Cu of the first back contact layer as a buffer layer, the diffusion path of the metal electrode can be blocked and defect generation can be reduced.

[0063] At the same time, the Te element in the second back contact layer ZnTe matches the CdTe lattice, reducing interface dangling bonds, passivating interface defects, and improving carrier lifetime.

[0064] In addition, the thermal expansion coefficient and lattice matching can be adjusted by setting a composite back contact layer in the cadmium telluride power generation glass.

[0065] Please refer to Figure 1 , the lattice constants of CdZnTe and ZnTe are close to those of CdTe. The lattice constant of CdTe is about ZnTe The coefficients of thermal expansion are also closely matched.

[0066] Therefore, the thermal expansion coefficients of the first back contact layer CdZnTe and the second back contact layer ZnTe in the composite back contact layer are also relatively matched, which reduces the stress accumulation at the interface, avoids cracks or defects in high-temperature processes (such as annealing), and effectively improves the long-term stability of the device.

[0067] Furthermore, the incorporation of a composite back contact layer in cadmium telluride solar cell glass can optimize back reflection and light management. The ZnTe compound material in the second back contact layer has a high refractive index of approximately 3.5, which enhances the back electrode's reflection of long-wavelength light (near-infrared). This allows photons not absorbed by the CdTe to be reflected back to the absorption layer, increasing the optical path length and boosting the short-circuit current.

[0068] In a second aspect, an embodiment of the present invention further provides a method for preparing the cadmium telluride power generation glass having a composite back contact layer of cadmium zinc telluride and zinc telluride as described above, the preparation method comprising the following steps:

[0069] Providing a substrate, and sequentially growing a TCO film layer, a window layer, and an absorption layer on the substrate to obtain a first structure;

[0070] Depositing a first back contact layer and a second back contact layer in sequence on the absorption layer of the first structure to obtain a second structure;

[0071] The second structure is subjected to heat treatment, and then a back electrode is deposited on the second back contact layer to obtain the power generation glass.

[0072] In some embodiments of the present invention, the deposition of the first back contact layer and the second back contact layer includes depositing the first back contact layer on the absorber layer by discontinuous film deposition and then annealing; and then depositing the second back contact layer on the first back contact layer.

[0073] In some embodiments of the present invention, annealing includes annealing under a N2 atmosphere.

[0074] In some embodiments of the present invention, the second back contact layer is preferably deposited by physical vapor deposition, with the background vacuum required to reach E-6 mbar and the substrate temperature required to be 150-300°C.

[0075] It is understood that the fabrication method provided by the embodiments of the present invention utilizes a discontinuous film deposition process to deposit a first back contact layer on the absorber layer, effectively reducing leakage current. Annealing treatment then aggregates the first back contact layer into islands, forming nanodots. A second back contact layer is then deposited on the first back contact layer.

[0076] The nanodots formed on the first back contact layer after heat treatment enhance short-wavelength transmission, prompting the second back contact layer to absorb more short-wavelength light. Simultaneously, the second back contact layer ensures efficient hole transmission, thereby reducing leakage current. The first and second back contact layers work together to synergistically improve Jsc and FF, resulting in excellent photoelectric performance for the cadmium telluride power generation glass prepared by the preparation method of the present invention.

[0077] It can be further understood that the first back contact layer CdZnTe is deposited first, and then annealed in N2 atmosphere. The CdZnTe material will aggregate in an island shape to form nanodots, and then ZnTe is deposited. The CdZnTe nanodots enhance the passage of short waves, and ZnTe absorbs more short-wave light. At the same time, ZnTe ensures the efficient transmission of holes, thereby reducing leakage current and synergistically improving the Jsc and FF of the cadmium telluride power generation glass.

[0078] In some embodiments of the present invention, the heat treatment is performed in an inert atmosphere or under vacuum.

[0079] In some embodiments of the present invention, the heat treatment temperature is 240-300°C.

[0080] In some embodiments of the present invention, the heat treatment time is 10 to 60 minutes.

[0081] The above is a detailed description of the present invention, and the following are embodiments of the present invention.

[0082] Example 1

[0083] This embodiment provides a cadmium telluride power generation glass 1 having a composite back contact layer of cadmium zinc telluride and zinc telluride. Parameter The specific structure is: a glass substrate and a TCO film layer, a CdSe window layer, a CdTe absorption layer, the composite back contact layer, and a back electrode sequentially arranged on the upper portion of the glass substrate.

[0084] The composite back contact layer includes a first back contact layer (back contact layer 1: CdZnTe: Ag) disposed on top of the absorber layer and a second back contact layer (back contact layer 1: ZnTe: Ag: Cu) disposed on top of the first contact layer. The first back contact layer is a metal-doped CdZnTe compound material; the second back contact layer is a metal-doped ZnTe compound material.

[0085] The CdZnTe compound material includes CdTe and ZnTe in a molar ratio of 6:4. The CdTe and ZnTe in the CdZnTe compound material are made of a 5N purity polycrystalline target.

[0086] Example 2

[0087] Based on Example 1, a method 1 for preparing cadmium telluride power generation glass 1 is provided. A substrate is provided, and a TCO film layer, a CdSe window layer, and a CdTe absorption layer are sequentially grown on the substrate to obtain a first structure. A first back contact layer and a second back contact layer are sequentially deposited on the absorption layer of the first structure to obtain a second structure. The second structure is heat treated, and a back electrode is then deposited on the second back contact layer to obtain the cadmium telluride power generation glass 1.

[0088] The deposition of the first back contact layer and the second back contact layer includes depositing the first back contact layer on the absorber layer by discontinuous film deposition and then annealing; and then depositing the second back contact layer on the first back contact layer.

[0089] Example 3

[0090] This embodiment provides a cadmium telluride power generation glass 2 having a composite back contact layer of cadmium zinc telluride and zinc telluride. The difference from the embodiment 1 is that the molar ratio of CdTe to ZnTe is 1:9.

[0091] Example 4

[0092] This embodiment provides a cadmium telluride power generation glass 3 having a composite back contact layer of cadmium zinc telluride and zinc telluride. The difference from the embodiment 1 is that the molar ratio of CdTe to ZnTe is 2:8.

[0093] Example 5

[0094] This embodiment provides a cadmium telluride power generation glass 4 having a composite back contact layer of cadmium zinc telluride and zinc telluride. The difference from the embodiment 1 is that the molar ratio of CdTe to ZnTe is 3:7.

[0095] Example 6

[0096] This embodiment provides a cadmium telluride power generation glass 5 having a composite back contact layer of cadmium zinc telluride and zinc telluride. The difference from the embodiment 1 is that the molar ratio of CdTe to ZnTe is 4:6.

[0097] Example 7

[0098] This embodiment provides a cadmium telluride power generation glass 6 having a composite back contact layer of cadmium zinc telluride and zinc telluride. The difference from the embodiment 1 is that the molar ratio of CdTe to ZnTe is 5:5.

[0099] Example 8

[0100] This embodiment provides a cadmium telluride power generation glass 7 having a composite back contact layer of cadmium zinc telluride and zinc telluride. The difference from the embodiment 1 is that the molar ratio of CdTe to ZnTe is 6:4.

[0101] Example 9

[0102] This embodiment provides a cadmium telluride power generation glass 8 having a composite back contact layer of cadmium zinc telluride and zinc telluride. The difference from Example 1 is that the molar ratio of CdTe to ZnTe is 7:3.

[0103] Example 10

[0104] This embodiment provides a cadmium telluride power generation glass 9 having a composite back contact layer of cadmium zinc telluride and zinc telluride. The difference from the embodiment 1 is that the molar ratio of CdTe to ZnTe is 8:2.

[0105] Example 11

[0106] This embodiment provides a cadmium telluride power generation glass 10 having a composite back contact layer of cadmium zinc telluride and zinc telluride. The difference from Example 1 is that the molar ratio of CdTe to ZnTe is 9:1.

[0107] Example 12

[0108] This embodiment provides a cadmium telluride power generation glass 11 having a composite back contact layer of cadmium zinc telluride and zinc telluride. The difference from the first embodiment is that the back contact layer is pure ZnTe (without Cu).

[0109] Example 13

[0110] This embodiment provides a cadmium telluride power generation glass 12 having a composite back contact layer of cadmium zinc telluride and zinc telluride. The difference from the first embodiment is that the back contact layer is Cu-doped ZnTe.

[0111] Comparative Example 1 (discontinuous deposition and no annealing)

[0112] Based on Example 2, a method for preparing cadmium telluride power generation glass is provided. A first back contact layer (the first back contact layer is not subjected to discontinuous film deposition and annealing), a second back contact layer (physical vapor deposition), and a back electrode are sequentially deposited on an absorption layer of a first structure to produce the power generation glass.

[0113] That is, in this embodiment, the only difference from embodiment 2 is that physical vapor deposition is used for the deposition of the first back contact layer and the second back contact layer (the first back contact layer is not subjected to discontinuous film deposition and annealing treatment) to obtain the cadmium telluride power generation glass 13.

[0114] Comparative Example 2 (Continuous Deposition, but No Annealing)

[0115] Based on Comparative Example 1, a method for preparing cadmium telluride power generation glass is provided. A first back contact layer (discontinuous film deposition without annealing), a second back contact layer (physical vapor deposition), and a back electrode are sequentially deposited on an absorber layer of a first structure to produce the power generation glass.

[0116] That is, in this embodiment, the only difference from Comparative Example 1 is that a discontinuous film layer deposition is performed on the first back contact layer but no annealing treatment is performed to obtain the cadmium telluride power generation glass 14.

[0117] Comparative Example 3 (discontinuous deposition, annealing only)

[0118] Based on Comparative Examples 1 and 2, a method for preparing cadmium telluride power generation glass is provided. A first back contact layer (physical vapor deposition followed by post-deposition annealing), a second back contact layer (physical vapor deposition), and a back electrode are sequentially deposited on an absorption layer of a first structure to produce the power generation glass.

[0119] That is, in this embodiment, the only difference from Comparative Example 1 is that physical vapor deposition is performed on the first back contact layer, and annealing treatment is performed after deposition to obtain the cadmium telluride power generation glass 15.

[0120] Comparative Example 4 (Deposition of only the first back contact layer)

[0121] Based on Example 2, a method for preparing cadmium telluride power generation glass is provided. A first back contact layer and a back electrode are sequentially deposited on an absorption layer of a first structure to obtain the power generation glass.

[0122] That is, in this embodiment, the only difference from embodiment 2 is that only the first back contact layer is deposited in the cadmium telluride power generation glass, and the second back contact layer is not deposited to obtain the cadmium telluride power generation glass 16 .

[0123] Comparative Example 5 (Deposition of only the second back contact layer)

[0124] Based on Example 2, a method for preparing cadmium telluride power generation glass is provided. A second back contact layer, a composite back contact layer, and a back electrode are sequentially deposited on the absorption layer of the first structure to obtain the power generation glass.

[0125] That is, in this embodiment, the only difference from embodiment 2 is that only the second back contact layer is deposited in the cadmium telluride power generation glass, and the first back contact layer is not deposited to obtain the cadmium telluride power generation glass 17 .

[0126] Test Example 1: Determination of the Photoelectric Performance of the Cadmium Telluride Power Generation Glass in Various Examples

[0127] 1.1 Experimental design

[0128] In this test example, the cadmium telluride power generation glasses of Example 1 and Examples 3-12 were used as Samples 1-12. The photovoltaic performance of Samples 1-12 was measured using the following parameters: conversion efficiency (%), open-circuit voltage (Voc), and fill factor (FF). The results are shown in Table 1.

[0129] 1.2 Test results

[0130] Table 1

[0131]

[0132]

[0133] 1.3 Analysis of test results

[0134] Through the above-mentioned photoelectric performance measurements of samples 1 to 12, it can be found that the conversion efficiency of sample 1 prepared using the preparation method of the present invention is 21.3%, the open circuit voltage is 895mV, and the fill factor is 77.1%. All three parameters perform best.

[0135] Comparing samples 1 to 12, it was found that when the molar ratio exceeded 6:4, the conversion efficiency continued to decline due to the excessive proportion of CdZnTe, which led to aggravated lattice mismatch and increased interface defects; when the molar ratio reached 8:2, it dropped to 17.5%; when the molar ratio reached 9:1, it further dropped to 16.2%.

[0136] Comparing samples 1 to 12, the open-circuit voltage (Voc) increases with the CdZnTe ratio, initially increasing and then decreasing due to bandgap adjustment. When the molar ratio reaches 9:1, carrier recombination intensifies, causing the open-circuit voltage to drop back to 850 mV, slightly lower than the 855 mV of Cu-doped ZnTe.

[0137] Comparing samples 1 to 12, it was found that the filling factor FF: at a high CdZnTe ratio, such as when the molar ratio is between 7:3 and 9:1, the filling factor FF slowly decreases due to the increase in series resistance, but is still higher than that of pure ZnTe. At a molar ratio of 9:1, it is 75.0%, close to the initial 74.5%.

[0138] Therefore, through the measurement of samples 1 to 12, the optimal molar ratio of CdTe to ZnTe is 6:4, at which the efficiency peak is 21.3%, and the open circuit voltage Voc and fill factor FF are both the highest.

[0139] Experimental Example 2: Comparison of the effects of different preparation methods on the performance of cadmium telluride power generation glass

[0140] 2.1 Experimental design

[0141] In this test example, the cadmium telluride power generation glass 1 obtained in Example 2 was used as experimental group 1, the cadmium telluride power generation glass 13 obtained in Comparative Example 1 was used as experimental group 2, and the cadmium telluride power generation glass 14 obtained in Comparative Example 2 was used as experimental group 3.

[0142] That is, experimental group 1: the first back contact layer is deposited discontinuously and then annealed. (discontinuous + heat treatment)

[0143] Experimental Group 2: No discontinuous film deposition or annealing of the first back contact layer. (Neither)

[0144] Experimental Group 3: Discontinuous deposition of the first back contact layer without annealing. (Continuous deposition without annealing)

[0145] The photoelectric performance of Experimental Groups 1 to 3 was measured, including external quantum efficiency, photoresponse time, open circuit voltage, and short circuit current. The results are shown in Table 2.

[0146] 2.2 Test results

[0147] Table 2

[0148] Experiment 1 Experiment 2 Experiment 3 External quantum efficiency (EQE) @ 600 nm (%) Light response time (ns) 78 65 42 Open circuit voltage Voc (V) 12 25 80 Short circuit current (mA / cm2) 0.82 0.75 0.58 Sample 28.5 24.3 15.7

[0149] 2.3 Analysis of test results

[0150] Comparing the optoelectronic performance of Experimental Groups 1, 2, and 3 shows that Experimental Group 1 performs best in external quantum efficiency, photoresponse time, open-circuit voltage, and short-circuit current. Experimental Group 2, which underwent discontinuous film deposition without annealing, performed worse than Experimental Group 1 in all respects. Experimental Group 3, which underwent discontinuous film deposition without annealing, also performed poorly.

[0151] This shows that in experimental group 1 using the preparation method of the present invention, the CdZnTe material will aggregate in an island shape to form nanodots, and then ZnTe will be deposited. The CdZnTe nanodots enhance the passage of short-wave light, and ZnTe absorbs more short-wave light. Annealing promotes ZnTe to fill grain boundary defects and reduce photogenerated carrier recombination. Therefore, the test results of experimental group 1 are the best.

[0152] Experimental Example 3: Comparison of the effects of different preparation methods on the performance of cadmium telluride power generation glass

[0153] 3.1 Experimental design

[0154] In this test example, the cadmium telluride electric power generating glass 1 obtained in Example 2 was used as the experimental group 1 (having both layers).

[0155] The cadmium telluride power generation glass 16 obtained in Comparative Example 4 was selected as Experimental Group 2 (only the first back contact layer).

[0156] The cadmium telluride power generation glass 17 obtained in comparative example 5 was selected as experimental group 3 (only the second back contact layer).

[0157] The photoelectric performance of Experimental Groups 1 to 3 was measured, including the following parameters: conversion efficiency, open-circuit voltage, short-circuit current, fill factor, and light decay stability. The results are shown in Table 3.

[0158] 3.2 Test results

[0159] Table 3

[0160]

[0161]

[0162] 3.3 Analysis of test results

[0163] According to the above test results, it can be seen that the performance of experimental group 1 of the present invention is the best, and it performs well in conversion efficiency, open circuit voltage, short circuit current, fill factor and light decay stability.

[0164] However, the performance of Experimental Group 2, which only provided the first back contact layer, and Experimental Group 3, which only provided the second back contact layer, were far inferior to Experimental Group 1.

[0165] This shows that the cadmium telluride power generation glass of the present invention selectively fills the Te vacancies at the CdZnTe grain boundaries with ZnTe, reducing the deep energy level defect density by 50%. At the same time, CdZnTe (Zn gradient-adjusted band gap 1.45~1.7eV) can absorb visible light, and the ZnTe (Eg≈2.26eV) in the second back contact layer can enhance the utilization of short-wavelength light (300~500nm), thereby achieving full spectrum coverage.

[0166] ZnTe inhibits the diffusion of Cd atoms toward the back electrode, reducing chemical degradation at the metal electrode-CdTe interface and improving light decay stability. Therefore, Experimental Group 1, using the inventive preparation method, achieved a simultaneous breakthrough in both efficiency (18.7%) and stability through the synergistic effect of the above principles.

[0167] Experimental Example 4: Comparison of the effects of different preparation methods on the performance of cadmium telluride power generation glass

[0168] 4.1 Experimental design

[0169] In this test example, the cadmium telluride electric power generating glass 1 obtained in Example 2 was used as the experimental group 1 (having both layers).

[0170] The cadmium telluride power generation glass 16 obtained in Comparative Example 4 was selected as Experimental Group 2 (having only the first back contact layer but no second back contact layer).

[0171] The deep level defect density and energy level position were measured for Experimental Group 1 and Experimental Group 2. The measurement results are shown in Table 4.

[0172] 4.2 Test results

[0173] Table 4

[0174]

[0175]

[0176] 4.3 Analysis of test results

[0177] According to the test results in Table 4 above, compared with the data of the experimental group 2 without the second back contact layer, the deep level defect density of the experimental group 1 of the present invention is reduced by 50%.

[0178] However, the performance of experimental group 2, which only provided the first back contact layer, was far inferior to that of experimental group 1.

[0179] This shows that the cadmium telluride power generation glass of the present invention reduces the deep energy level defect density by 50% by selectively filling the Te vacancies at the grain boundary of the first back contact layer CdZnTe with ZnTe, further realizing the coordinated regulation of the first contact layer and the second contact layer.

[0180] Experimental Example 5: Comparison of the effects of different preparation methods on the performance of cadmium telluride power generation glass

[0181] 5.1 Experimental design

[0182] In this test example, the cadmium telluride electric power generating glass 1 obtained in Example 2 was used as the experimental group 1 (both layers had: CdZnTe+ZnTe thin films).

[0183] The cadmium telluride power generation glass 16 obtained in Comparative Example 4 was selected as Experimental Group 2 (having only the first back contact layer but no second back contact layer).

[0184] The carrier lifetime τ1 (ns) and surface recombination velocity SRV (cm / s) were measured for Experimental Group 1 and Experimental Group 2, respectively. The measurement results are shown in Table 5.

[0185] 5.2 Test results

[0186] Table 5

[0187] Carrier lifetime τ1 (ns) τ2 (ns) Surface recombination velocity SRV (cm / s) Experiment 1 Experiment 2 15 120 ～1*103 ​ 2.5 25 ～1*105

[0188] 5.3 Analysis of test results

[0189] The experimental results in Table 5 show that compared with the experimental data of Experimental Group 2 without a second back contact layer, the carrier lifetime τ1 (ns) of Experimental Group 1 of the present invention is significantly extended to 15ns. The surface recombination velocity (SRV) of Experimental Group 1 of the present invention is reduced by 2 orders of magnitude.

[0190] The performance of experimental group 2 (only the first back contact layer, no second back contact layer) in which only the first back contact layer is set is far inferior to that of experimental group 1.

[0191] This shows that the preparation method of the cadmium telluride power generation glass of the present invention can absorb visible light by setting the first back contact layer of CdZnTe (Zn gradient adjustment band gap 1.45~1.7eV), and the second back contact layer of ZnTe (Eg≈2.26eV) can enhance the utilization of short wavelength light (300~500nm), thereby achieving full spectrum coverage.

[0192] The ZnTe film of the second back contact layer covers the surface of the first back contact layer CdZnTe, which can reduce the surface recombination velocity (SRV) from 10 to 10 by chemical bonding (Zn-Te) and field effect passivation (built-in electric field). 5 cm / s down to 10 3 cm / s.

[0193] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. Persons skilled in the art will appreciate that improvements and modifications may be made without departing from the spirit and scope of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A cadmium telluride power generation glass having a composite back contact layer of cadmium zinc telluride and zinc telluride, characterized in that: The power generation glass includes a substrate and a TCO film layer, a window layer, an absorption layer, a composite back contact layer and a back electrode sequentially arranged on the upper portion of the substrate.

2. The cadmium telluride power generation glass having a composite back contact layer of cadmium zinc telluride and zinc telluride according to claim 1, characterized in that: The composite back contact layer includes a first back contact layer disposed on the absorber layer and a second back contact layer disposed on the first contact layer.

3. The cadmium telluride power generation glass having a composite back contact layer of cadmium zinc telluride and zinc telluride according to claim 2, characterized in that: The first back contact layer is a metal-doped CdZnTe compound material; the second back contact layer is a metal-doped ZnTe compound material.

4. The cadmium telluride power generation glass having a composite back contact layer of cadmium zinc telluride and zinc telluride according to claim 3, characterized in that: The CdZnTe compound material includes CdTe and ZnTe in a molar ratio of 6:

4.

5. The cadmium telluride power generation glass having a composite back contact layer of cadmium zinc telluride and zinc telluride according to claim 3, characterized in that: The metal doping material of the CdZnTe compound material is one or more of Ag, Cu, Hg and Au.

6. The cadmium telluride power generation glass having a composite back contact layer of cadmium zinc telluride and zinc telluride according to claim 5, characterized in that: The doping ratio of the metal doping material in the CdZnTe compound material is 100 ppm to 1 wt %.

7. The cadmium telluride power generation glass having a composite back contact layer of cadmium zinc telluride and zinc telluride according to claim 3, characterized in that: The metal doping material of the ZnTe compound material is one or more of Ag, Cu, Hg and Au.

8. The cadmium telluride power generation glass having a composite back contact layer of cadmium zinc telluride and zinc telluride according to claim 7, characterized in that: The metal doping material of the ZnTe compound material is Ag and Cu co-doped, the doping ratio of Ag is 100ppm-1%wt, and the doping ratio of Cu is 100ppm-3%wt.

9. A method for preparing a cadmium telluride power generation glass having a composite back contact layer of cadmium zinc telluride and zinc telluride according to any one of claims 1 to 8, characterized in that: The following steps are involved: Providing a substrate, and sequentially growing a TCO film layer, a window layer, and an absorption layer on the substrate to obtain a first structure; Depositing a first back contact layer and a second back contact layer in sequence on the absorption layer of the first structure to obtain a second structure; The second structure is subjected to heat treatment, and then a back electrode is deposited on the second back contact layer to obtain the power generation glass.

10. The method for preparing a cadmium telluride power generation glass having a composite back contact layer of cadmium zinc telluride and zinc telluride according to claim 9, characterized in that: The deposition of the first back contact layer and the second back contact layer includes depositing the first back contact layer on the absorber layer by discontinuous film deposition and then annealing; and then depositing the second back contact layer on the first back contact layer.

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