Study on the Performance of Oxygen-Rich Zn(O,S) Buffers Fabricated by Sputtering Deposition and Zn(O,S)/Cu(In,Ga)(S,Se)2 Interfaces

Yuxian Li; Daming Zhuang; Ming Zhao; Chen Wang; Hao Tong; Liangzheng Dong; Shengye Tao; Hanpeng Wang

doi:10.1021/acsami.2c04919

Study on the Performance of Oxygen-Rich Zn(O,S) Buffers Fabricated by Sputtering Deposition and Zn(O,S)/Cu(In,Ga)(S,Se)₂ Interfaces

ACS Appl Mater Interfaces. 2022 Jun 1;14(21):24435-24446. doi: 10.1021/acsami.2c04919. Epub 2022 May 17.

Authors

Yuxian Li¹, Daming Zhuang^{1

2

3}, Ming Zhao^{1

2

3}, Chen Wang¹, Hao Tong⁴, Liangzheng Dong¹, Shengye Tao¹, Hanpeng Wang¹

Affiliations

¹ School of Materials Science and Engineering, Tsinghua University, 100084 Beijing, PR China.
² Key Laboratory for Advanced Materials Processing Technology of Ministry of Education, 100084 Beijing, PR China.
³ State Key Laboratory of New Ceramics and Fine Processing, 100084 Beijing, PR China.
⁴ College of Mechanical and Vehicle Engineering, Taiyuan University of Technology, 030024 Taiyuan, PR China.

PMID: 35580322
DOI: 10.1021/acsami.2c04919

Abstract

We developed a novel process for fabricating oxygen-rich Zn(O,S) buffer layers by magnetron reactive sputtering with a single oxygen-rich Zn(O,S) target, suitable for industrial all-dry production. Then, we successfully fabricated Cd-free Cu(In,Ga)(S,Se)₂ (CIGSSe) solar cells. By varying the oxygen partial pressure during sputtering from 0 to 20%, we precisely controlled the Zn(O,S) composition, then systematically investigated its effects on the quality of oxygen-rich Zn(O,S) films, the properties of formed p-n junctions, and the performance of CIGSSe solar cells with Zn(O,S) buffer. We demonstrated that reactive sputtering with a Zn(O,S) target can generate a homogeneous, high-quality oxygen-rich Zn(O,S) buffer on large-area substrates. We observed a unique and unusual phenomenon: the appropriate content of secondary phase ZnSO₄ and ZnSO₃ improved the band alignment for oxygen-rich Zn(O,S). Combining our proposed schematic diagram of band alignmentat the Zn(O,S)/CIGSSe interface, we established a crucial correlation between the device performance and the interfacial properties at the p-n junction. For the CIGSSe device performance, the band alignment matching at the heterojunction plays a primary role, and the quality of oxygen-rich Zn(O,S) films plays a secondary role. Consequently, an excellent oxygen-rich Zn(O,S) buffer can be obtained with 10% Zn(O,S) deposition oxygen partial pressure , and the optimized device shows a higher V_oc (447 mV) and a similar conversion efficiency (11.2%) than conventional CIGSSe devices with CdS buffer.

Keywords: Cd-free Cu(In,Ga)Se2 solar cell; band alignment; oxygen-rich Zn(O,S); p−n junction property; reactive sputtering; secondary phase in Zn(O,S).