Cadmium Selenide Based Photovoltaic Devices And Methods For Forming The Same

Patent metadata

Field	Value
Publication number	US-2025063848-A1
Application number	US-202218723069-A
Country	US
Kind code	A1
Filing date	Dec 23, 2022
Priority date	Dec 23, 2021
Publication date	Feb 20, 2025
Grant date	—

Abstract

Provided are photovoltaic devices with polycrystalline type II-VI semiconductor absorber materials including n-type absorber compositions and having p-type hole contact layers are described herein. Methods of treating semiconductor absorber layers and forming hole contact layers are described.

First claim

What is claimed is:

1 . A tandem photovoltaic device comprising an upper submodule over a lower submodule, wherein the upper submodule comprises:
an absorber layer consisting essentially of CdSe, wherein:
the absorber layer is n-type;
the absorber layer has an n type carrier concentration of less than 1×10 17 cm −3 ; and
the absorber layer includes chlorine in grain boundaries at a level equal to or greater than 1×10 13 cm −3 in the grain boundaries as measured by secondary-ion mass spectrometry; and
a hole contact forming a p-n junction with the absorber layer.

2 - 3 . (canceled)

4 . The tandem photovoltaic device of claim 1 , wherein the absorber layer has an n type carrier concentration of less than or equal to 1×10 16 cm −3 .

5 - 6 . (canceled)

7 . The tandem photovoltaic device of claim 1 , wherein the absorber layer includes a dopant comprising rubidium (Rb).

8 . The tandem photovoltaic device of claim 1 , wherein the absorber layer is a polycrystalline film having a thickness in a range of 0.25 μm to 2.0 μm and an average grain size in a range of 1.3 μm to 3.0 μm.

9 . The tandem photovoltaic device of claim 1 , wherein the absorber layer is a polycrystalline film wherein a ratio of grains having (103) orientation relative to (002) orientation is equal to or greater than 1:1000.

10 . The tandem photovoltaic device of claim 1 , wherein the hole contact comprises a high work function layer having a work function greater or equal to than 5 eV.

11 . The tandem photovoltaic device of claim 1 , wherein the hole contact comprises a layer having a p mobility to n mobility ratio of less than 2.

12 . The tandem photovoltaic device of claim 1 , wherein:
the hole contact comprises a p+ layer of a n+/p+ tunnel junction, n+/p+ tunnel junction has a n+ side and a p+ side, and the absorber layer forms the p-n junction with the p+ side of the n+/p+ tunnel junction.

13 . The tandem photovoltaic device of claim 12 , wherein:
the n+ side of the n+/p+ tunnel junction comprises a layer of a metal oxide doped n+, and the metal oxide comprises at least one of: SnO 2 :F, ITO, Cd 2 SnO 4 , WO 3 , MoO 3 , CrO 3 , or V 2 O 5 .

14 - 21 . (canceled)

22 . The tandem photovoltaic device of claim 12 , wherein the n+ side of the n+/p+ tunnel junction comprises at least one of: GaP, BP, or ZnSe.

23 - 24 . (canceled)

25 . The tandem photovoltaic device of claim 1 , wherein the hole contact comprises a p-type transparent conductive oxide.

26 - 27 . (canceled)

28 . The tandem photovoltaic device of claim 25 , wherein the p-type transparent conductive oxide is doped with B, Mg, N, Sb, or any combination thereof.

29 . The tandem photovoltaic device of claim 1 , wherein the hole contact comprises at least one of: PTAA, PDI, CBP, TCTA, TCP, F8BT, CuAlS 2 , CuAlSe 2 , CuGaO 2 , GeMgP 2 , BP, GaP, ZnSe, TaO x N (1-x) , MoS 2 , WS 2 , NbS 2 , VS, TaS 2 , TiS 2 , or a p-type alloy of Zn, S, Se, and Te.

30 - 45 . (canceled)

46 . A method for forming an absorber layer of a photovoltaic device comprising:
providing a layer stack comprising a p-type layer; depositing a polycrystalline film over the p-type layer, wherein the polycrystalline film consists essentially of CdSe; contacting an exposed surface of the polycrystalline film with a halogen compound and an accelerant; heating the polycrystalline film in a controlled environment to form the absorber layer, wherein the controlled environment comprises oxygen and selenium, whereby:
the absorber layer has an n type carrier concentration of less than 1×10 17 cm −3 ; and
the absorber layer includes chlorine in grain boundaries at a level equal to or greater than 1×10 13 in the grain boundaries.

47 - 48 . (canceled)

49 . The method of claim 46 , wherein the halogen compound comprises at least one of: CdCl 2 , NH 4 Cl, CdBr 2 , CdI 2 , MgCl 2 , or Ba(ClO 3 ) 2 .

50 . The method of claim 46 , wherein the accelerant comprises at least one of: Li, Na, K, Rb, or Cs.

51 . The method of claim 46 , wherein the accelerant comprises rubidium chloride.

52 - 53 . (canceled)

54 . The method of claim 46 , wherein an average grain size of the polycrystalline film is in a range of 1.3 μm to 3.0 μm.

55 . A method for forming a photovoltaic device comprising:
annealing an absorber layer consisting essentially of CdSe in the presence of a halogen compound, whereby a grain size of the absorber layer grows and halogen diffuses into the absorber layer; and treating the absorber layer by heating in a controlled environment comprising Se and O 2 , whereby the treating reduces Se vacancies in the absorber layer.

56 . The method of claim 55 , wherein the annealing step and the treating step are performed sequentially, wherein the annealing step precedes the treating step.

57 - 82 . (canceled)

Assignees

• First Solar Inc

Inventors

• Ablekim Tursun
• Grover Sachit
• Hack James
• Hettiaratchy Elline
• Hill Taylor
• Kniajanski Sergei
• Metzger Wyatt
• Valdes Nicholas
• Xiong Gang

Classifications

• H10F77/1233

  characterised by the dopants · CPC title

• H10F71/125

  The active layers comprising only Group II-VI materials, e.g. CdS, ZnS or CdTe · CPC title

• H10F71/128

  Annealing · CPC title

• H10F10/19

  Photovoltaic cells having multiple potential barriers of different types, e.g. tandem cells having both PN and PIN junctions · CPC title

• H10F10/16

  Photovoltaic cells having only PN heterojunction potential barriers · CPC title