Back Contact Interfacial Modification in Highly-Efficient All-Inorganic Planar n-i-p Sb2Se3 Solar Cells

Cong Liu; Kai Shen; Dongxu Lin; Ye Cao; Shudi Qiu; Jianzha Zheng; Feixiong Bao; Yanyan Gao; Hongbing Zhu; Zhiqiang Li; Yaohua Mai

doi:10.1021/acsami.0c10629

Back Contact Interfacial Modification in Highly-Efficient All-Inorganic Planar n-i-p Sb₂Se₃ Solar Cells

ACS Appl Mater Interfaces. 2020 Aug 26;12(34):38397-38405. doi: 10.1021/acsami.0c10629. Epub 2020 Aug 14.

Authors

Cong Liu¹, Kai Shen¹, Dongxu Lin², Ye Cao³, Shudi Qiu¹, Jianzha Zheng¹, Feixiong Bao¹, Yanyan Gao¹, Hongbing Zhu¹, Zhiqiang Li⁴, Yaohua Mai¹

Affiliations

¹ Institute of New Energy Technology, College of Information Science and Technology, Jinan University, Guangzhou 510632, China.
² Siyuan Laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Department of Physics, Jinan University, Guangzhou 510632, China.
³ The College of Electronic Information, Qingdao University, Qingdao 266071, China.
⁴ National-Local Joint Engineering Laboratory of New Energy Photoelectric Devices, College of Physics Science and Technology, Hebei University, Baoding 071002, China.

PMID: 32805980
DOI: 10.1021/acsami.0c10629

Abstract

Sb₂Se₃ is an emerging and promising light-absorbing material with superior photovoltaic properties. However, the specific one-dimensional structure of Sb₂Se₃ limits the doping density, preventing a high built-in potential. Moreover, in the superstrate devices the back contact is often non-ohmic. In this work, we have successfully applied tungsten oxide (WO_3-x) as a hole-transport layer in superstrate n-i-p Sb₂Se₃ solar cells. It is found that an interfacial dipole is formed at Sb₂Se₃/WO_3-x interface via Sb-W bonds, which reduces the barrier for hole extraction. Meantime, gap states are present at a suitable energy level to serve as intermediate states for hole-transport from the Sb₂Se₃ absorber to the metal anode. In addition, the introduction of WO_3-x can suppress carrier recombination at the back interface, enhance the built-in potential, and improve the spectral response in the long-wavelength region. Consequently, the superstrate devices with the incorporated WO_3-x layer achieve a champion efficiency of 7.10% due to the enhancement of all device parameters. Furthermore, the all-inorganic devices with WO_3-x hole-transport layer exhibit excellent air stability and thermal stability.

Keywords: Sb2Se3 solar cells; WO3-x; gap states; hole-transport layer; interfacial dipole.