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JP-7854985-B2 - Transparent conductive layer, and photovoltaic device comprising the transparent conductive layer

JP7854985B2JP 7854985 B2JP7854985 B2JP 7854985B2JP-7854985-B2

Inventors

  • ベッカー，ジェームズ
  • ヘンドリクス，マーク
  • ヒューバー，ウィリアム
  • ケファート，ジェイソン
  • ロス，アンドレイ
  • ジャーン，ウエイ

Assignees

  • ファースト・ソーラー・インコーポレーテッド

Dates

Publication Date
20260507
Application Date
20210921
Priority Date
20200921

Claims (20)

  1. A tandem photovoltaic device comprising a thin film bond, a second bond, and a transparent conductive layer, The thin film junction comprises an absorber layer containing cadmium and tellurium; The second junction is electrically connected to the thin film junction, wherein the second junction is closer to the back surface of the tandem photovoltaic device than the thin film junction; and the transparent conductive layer is positioned between the thin film junction and the second junction, wherein the transparent conductive layer comprises a high conductivity layer, a diffusion barrier layer and a capping layer. The diffusion barrier layer contains cadmium stannate, The capping layer contains cadmium stannate, The high conductivity layer comprises cadmium oxide having a charge density greater than 1 × 10¹⁸ cm⁻³ , and the high conductivity layer is located between the diffusion barrier layer and the capping layer. The tandem photovoltaic device shown above.
  2. The tandem photovoltaic device according to claim 1, wherein one of the diffusion barrier layer and the capping layer contains amorphous cadmium stannate, where the amorphous cadmium stannate is a CdxSnO4 material (wherein x is a value in the range of 0.5 to 2).
  3. The tandem photovoltaic device according to claim 1 or claim 2, wherein the cadmium oxide in the high conductivity layer is doped n++ with an oxide dopant, and the cadmium oxide doped n++ with the oxide dopant has a charge density greater than 1 × 10¹⁸ cm⁻³ .
  4. The tandem photovoltaic device according to claim 3 , wherein the oxide dopant is In₂O₃ .
  5. The tandem photovoltaic device according to claim 3 , wherein the oxide dopant is Ga₂O₃ .
  6. The tandem photovoltaic device according to any one of claims 1 to 5, wherein the capping layer is in contact with the high conductivity layer.
  7. The tandem photovoltaic device according to any one of claims 1 to 6, wherein the capping layer contains amorphous cadmium stannate.
  8. The tandem photovoltaic device according to any one of claims 1 to 7, wherein the diffusion barrier layer is in contact with the high conductivity layer, and the diffusion barrier layer is in contact with the back contact layer of the thin film junction.
  9. The tandem photovoltaic device according to claim 8, wherein the diffusion barrier layer contains amorphous cadmium stannate.
  10. The tandem photovoltaic device according to claim 1, wherein the high conductivity layer is thicker than at least one of the diffusion barrier layer or the capping layer, and the thickness of the high conductivity layer is less than 300 nm.
  11. A tandem photovoltaic device according to any one of claims 1 to 10, wherein the thickness of the transparent conductive layer exceeds 40 nm and is less than 400 nm.
  12. The tandem photovoltaic device according to any one of claims 1 to 11, wherein the transparent conductive layer has an average transmittance of more than 85% for light having a wavelength of 800 nm to 1,300 nm.
  13. The tandem photovoltaic device according to any one of claims 1 to 12, wherein the average quantum efficiency of the thin-film junction in light having wavelengths of 800 nm to 1,300 nm is less than 20%.
  14. The tandem photovoltaic device according to any one of claims 1 to 13, wherein the absorber layer of the thin-film junction comprises at least one of zinc and selenium.
  15. The tandem photovoltaic device according to any one of claims 1 to 14, wherein the thin film junction comprises a back contact layer, the back contact layer is disposed between the absorber layer and the transparent conductive layer, and the back contact layer comprises zinc and tellurium.
  16. The tandem photovoltaic device according to any one of claims 1 to 15, wherein the average quantum efficiency of the second junction in light having wavelengths of 800 nm to 1,300 nm is greater than 50%, and the second junction includes a semiconductor different from the absorber layer of the thin film junction.
  17. The tandem photovoltaic device according to any one of claims 1 to 16, wherein the thin film junction comprises a transparent conductive oxide layer, and the absorber layer of the thin film junction is disposed between the transparent conductive oxide layer and the transparent conductive layer.
  18. The tandem photovoltaic device according to claim 17, wherein the transparent conductive oxide layer contains indium tin oxide.
  19. The tandem photovoltaic device according to claim 17, wherein the transparent conductive oxide layer contains cadmium stannate, and the cadmium stannate is crystalline.
  20. A tandem photovoltaic device comprising a thin film bond, a second bond, and a transparent conductive layer, The thin film junction comprises an absorber layer containing cadmium and tellurium; The second junction is electrically connected to the thin film junction; and the transparent conductive layer is disposed between the thin film junction and the second junction, wherein the transparent conductive layer comprises a high conductivity layer, a diffusion barrier layer and a capping layer. The diffusion barrier layer contains cadmium stannate, The capping layer contains cadmium stannate, The high conductivity layer contains cadmium oxide having a charge density greater than 1 × 10¹⁸ cm⁻³ , and the high conductivity layer is located between the diffusion barrier layer and the capping layer. The above-mentioned tandem photovoltaic device.

Description

[0001] This specification generally relates to transparent conductive layers for photovoltaic devices, and more specifically to the use of specific combinations of materials and layer parameters for improving the efficiency of photovoltaic devices. [0002] Photovoltaic devices generate electricity by converting light into electricity using semiconductor materials that exhibit the photovoltaic effect. Certain semiconductor materials can be difficult to manufacture. For example, material layers placed on top of a semiconductor material may have both desirable and undesirable properties. Unfortunately, the manufacturing processes necessary to efficiently produce the semiconductor material may enhance the undesirable properties of other material layers. Therefore, material layers added to a photovoltaic device to improve efficiency may ultimately decrease its efficiency. [0003]Therefore, an alternative layer structure is needed for use in photovoltaic devices. [0004]This figure schematically illustrates a photovoltaic device according to one or more embodiments shown and described herein.[0005] This figure schematically shows a cross-section along 2-2 of the photovoltaic device of Figure 1 according to one or more embodiments shown and described herein.[0006] This figure schematically shows a substrate according to one or more embodiments shown and described herein.[0007] This figure schematically shows the transparent conductive layer of the photovoltaic device of Figures 1 and 2 according to one or more embodiments described herein.[0008] This figure schematically shows a cross-section of a tandem photovoltaic device according to one or more embodiments shown and described herein. [0009] A photovoltaic device may be formed from a laminate of functional layers formed on a substrate. One or more functional layers may include thin films of material; that is, the photovoltaic device may be a thin-film photovoltaic device. A thin-film photovoltaic device may include an absorber layer for converting light into charge carriers and a conductive layer for collecting charge carriers. In some cases, the conductive layer may be formed in the direction of the back surface of the module relative to the absorber layer. In single-junction devices, the conductive layer may be located on the back surface of the module, and an opaque metal layer can be used as a component. However, such opaque layers may not be suitable for use as a conductive layer located between junctions in multi-junction photovoltaic devices or tandem photovoltaic devices. Embodiments provided herein relate to a transparent conductive layer and a photovoltaic device comprising the transparent conductive layer. The disclosed transparent conductive layer improves the reliability and durability of the current collector of the photovoltaic device and, at the same time, enables the use of the photovoltaic device in applications requiring transparency, such as windows, skylights, and tandem devices. [0010] Referring here to Figure 1, one embodiment of the photovoltaic device 100 is schematically shown. The photovoltaic device 100 may be configured to receive light and convert the light into electrical energy, for example, photons may be absorbed from light and converted into electric current via the photovoltaic effect. Therefore, for discussion and clarification, the photovoltaic device 100 may define a front surface 102 configured to face a primary light source, such as the sun. Furthermore, the photovoltaic device 100 may also define a back surface 104 isolated from the front surface 102, for example, by multiple functional layers of material. Note that the term “light” can refer to various wavelengths of the electromagnetic spectrum, including, but is not limited to, ultraviolet (UV), infrared (IR), and wavelengths of the visible portion of the electromagnetic spectrum. “Sunlight” as used herein refers to light emitted by the sun. [0011] The photovoltaic device 100 may include a plurality of layers arranged between the front surface 102 and the back surface 104. As used herein, the term “layer” refers to the thickness of the material provided on the surface. Each layer may cover all or any portion of an adjacent surface. In some embodiments, the layers of the photovoltaic device 100 may be divided into an array of solar cells 200. For example, the photovoltaic device 100 may be scribed according to a plurality of series scribes 202 and a plurality of parallel scribes 204. The series scribes 202 extend along the length Y of the photovoltaic device 100 and can define the boundaries of the solar cells 200 along the length Y of the photovoltaic device 100. A plurality of adjacent cells in the solar cells 200 may be connected in series along the width X of the photovoltaic device 100. In other words, a monolithic interconnect of a plurality of adjacent cells 200 may be formed adjacent to the series scribes 202. The parallel scribe 204 extends along the width X of