Title: Photovoltaic Device with over 5% Efficiency Based on an n-Type Ag₂ZnSnSe₄ Absorber

Abstract

The kesterite material Cu₂ZnSn(S,Se)₄ (CZTSSe) is an attractive earth–abundant semiconductor for photovoltaics. However, the power conversion efficiency is limited by a large density of I–II antisite defects, which cause severe band tailing and open–circuit voltage loss. Ag₂ZnSnSe₄ (AZTSe) is a promising alternative to CZTSSe with a substantially lower I–II antisite defect density and smaller band tailing. AZTSe is weakly n–type, and this study reports for the first time on how the carrier density is impacted by stoichiometry. Here, this study presents the first–ever photovoltaic device based on AZTSe, which exhibits an efficiency of 5.2%, which is the highest value reported for an n–type thin–film absorber. Due to the weakly n–type nature of the absorber, a new architecture is employed (SnO:F/AZTSe/MoO₃/ITO) to replace conventional contacts and buffer materials. Using this platform, it is shown that the band tailing parameter in AZTSe more closely resembles that of CIGSe than CZTSSe, underscoring the strong promise of this absorber. In demonstrating the ability to collect photogenerated carriers from AZTSe, this study paves the way for novel thin–film heterojunction architectures where light absorption in the n–type device layer can supplement absorption in the p–type layer as opposed to producing a net optical loss.

Authors:

Gershon, Talia ^[1]; Sardashti, Kasra ^[2]; Gunawan, Oki ^[1]; Mankad, Ravin ^[1]; Singh, Saurabh ^[1]; Lee, Yun Seog ^[1]; Ott, John A. ^[1]; Kummel, Andrew ^[2]; Haight, Richard ^[1]

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+ Show Author Affiliations

1. IBM T J Watson Research Center, Yorktown Heights, NY (United States)
2. University of California, San Diego, CA (United States)

Publication Date:

Mon Aug 22 00:00:00 EDT 2016

Research Org.:

International Business Machines Corp., Armonk, NY (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:

1533062

Alternate Identifier(s):

OSTI ID: 1401226

Grant/Contract Number:  

EE0006334

Resource Type:

Accepted Manuscript

Journal Name:

Advanced Energy Materials

Additional Journal Information:

Journal Volume: 6; Journal Issue: 22; Journal ID: ISSN 1614-6832

Publisher:

Wiley

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Chemistry; Energy & Fuels; Materials Science; Physics; AZTSe; Band tailing; CZTSSe; Kesterite; N‐type