Thin-film crystalline silicon solar cell using a nanoimprinted photonic-plasmonic back-reflector structure

Patent metadata

Field	Value
Publication number	US-12166147-B2
Application number	US-202217834242-A
Country	US
Kind code	B2
Filing date	Jun 7, 2022
Priority date	Dec 9, 2019
Publication date	Dec 10, 2024
Grant date	Dec 10, 2024

Abstract

Disclosed are embodiments of a thin-film photovoltaic technology including a single-junction crystalline silicon solar cell with a photonic-plasmonic back-reflector structure for lightweight, flexible energy conversion applications. The back-reflector enables high absorption for long-wavelength and near-infrared photons via diffraction and light-concentration, implemented by periodic texturing of the bottom-contact layer by nanoimprint lithography. The thin-film crystalline silicon solar cell is implemented in a heterojunction design with amorphous silicon, where plasma enhanced chemical vapor deposition (PECVD) is used for all device layers, including a low-temperature crystalline silicon deposition step. Excimer laser crystallization is used to integrate crystalline and amorphous silicon within a monolithic process, where a thin layer of amorphous silicon is converted to a crystalline silicon seed layer prior to deposition of a crystalline silicon absorber layer via PECVD. The crystalline nature of the absorber layer and the back-reflector enable efficiencies higher than what is achievable in other thin-film silicon devices.

First claim

What is claimed is:

1. A solar cell device comprising:
a photonic-plasmonic back-reflector comprising a photonic crystal and a reflective and plasmonic metal contact disposed on the photonic crystal;
a first layer of amorphous silicon disposed on the metal contact of the back reflector;
a seed layer crystallized from a portion of a thickness of the first layer of amorphous silicon using a laser annealing process;
a crystalline silicon absorber layer disposed on the laser annealed seed-layer, the crystalline silicon absorber layer comprising a thickness of 20 μm or less; and
a second layer of amorphous silicon disposed on the crystalline silicon absorber layer.

2. The solar cell device of claim 1 , wherein the photonic-plasmonic back-reflector includes a transparent conductive oxide layer that is disposed on top of the metal contact to form a tunnel-diode to the first layer of amorphous silicon.

3. The solar cell device of claim 2 , wherein the transparent conductive oxide layer comprises at least one of aluminum-doped zinc oxide, silicon dioxide, or zinc oxide.

4. The solar cell device of claim 1 , wherein the first layer of amorphous silicon is n-type doped.

5. The solar cell device of claim 1 , wherein the first layer of amorphous silicon is n-type doped at a concentration of at least 1×10 18 cm −3 .

6. The solar cell device of claim 1 , wherein the first layer of amorphous silicon is p-type doped.

7. The solar cell device of claim 1 , wherein the first layer of amorphous silicon is p-type doped at a concentration of at least 1×10 18 cm −3 .

8. The solar cell device of claim 1 , wherein the crystalline silicon absorber layer is deposited using PECVD at a deposition temperature of 550° C. or less.

9. The solar cell device of claim 1 , wherein the first layer of amorphous silicon is hydrogenated at a concentration of 10 at % or less.

10. The solar cell device of claim 1 , wherein the first layer of amorphous silicon is hydrogenated at a concentration of 5 at % or less.

11. The solar cell device of claim 1 , wherein the crystalline silicon absorber layer comprises a thickness of 10 μm or less.

12. The solar cell device of claim 1 , wherein the crystalline silicon absorber layer comprises a thickness of 5 μm or less.

13. The solar cell device of claim 1 , wherein the crystalline silicon absorber layer comprises a thickness of 2 μm or less.

14. The solar cell device of claim 1 , wherein the seed layer after laser annealing contains crystalline grains of at least 1 μm.

15. The solar cell device of claim 1 , wherein the solar cell device is configured as a multi-junction device with one or more additional junctions disposed in a series configuration.

16. The solar cell device of claim 1 , wherein at least one of the first layer of amorphous silicon, the seed layer, the crystalline silicon absorber layer, or the second layer of amorphous silicon is alloyed with an additional element to increase or decrease a bandgap of the first layer of amorphous silicon, the seed layer, the crystalline silicon absorber layer, or the second layer of amorphous silicon.

17. The solar cell device of claim 16 , wherein the additional element comprises at least one of germanium or carbon.

18. The solar cell device of claim 1 , where the first or second layers of amorphous silicon within the solar cell device are alloyed with an additional element to increase or decrease a bandgap of the first or second layers of amorphous silicon and create a heterojunction with the crystalline silicon absorber layer.

19. The solar cell device of claim 18 , wherein the additional element comprises at least one of germanium or carbon.

20. The solar cell device of claim 1 , where the crystalline silicon absorber layer is undoped, n-type doped, or p-type doped.

21. The solar cell device of claim 1 , where the crystalline silicon absorber layer undergoes hydrogen passivation during or after deposition to reduce defects associated with grain boundaries.

Assignees

• Dalal Vikram
• Keogh David
• Pacific Integrated Energy Inc
• Univ Iowa State Res Found Inc

Inventors

• Dalal Vikram
• Keogh David

Classifications

• H10F77/413

  directly associated or integrated with the devices, e.g. back reflectors (directly associated or integrated with photovoltaic cells H10F77/42) · CPC title

• H10F71/128

  Annealing · CPC title

• H10F71/103

  including only Group IV materials · CPC title

• H10F10/166

  the Group IV-IV heterojunctions being heterojunctions of crystalline and amorphous materials, e.g. silicon heterojunction [SHJ] photovoltaic cells · CPC title

• H10F71/131

  Recrystallisation; Crystallization of amorphous or microcrystalline semiconductors · CPC title