New Solution-Processed Surface Treatment to Improve the Photovoltaic Properties of Electrodeposited Cu(In,Ga)Se2 (CIGSe) Solar Cells

Qing Gao; Yongheng Zhang; Jianping Ao; Jinlian Bi; Liyong Yao; Jiajia Guo; Guozhong Sun; Wei Liu; Fangfang Liu; Yi Zhang; Wei Li

doi:10.1021/acsami.1c00270

New Solution-Processed Surface Treatment to Improve the Photovoltaic Properties of Electrodeposited Cu(In,Ga)Se₂ (CIGSe) Solar Cells

ACS Appl Mater Interfaces. 2021 Jun 2;13(21):25451-25460. doi: 10.1021/acsami.1c00270. Epub 2021 May 19.

Authors

Qing Gao¹, Yongheng Zhang¹, Jianping Ao¹, Jinlian Bi², Liyong Yao³, Jiajia Guo¹, Guozhong Sun¹, Wei Liu¹, Fangfang Liu¹, Yi Zhang¹, Wei Li²

Affiliations

¹ Key Laboratory of Photo-electronic Thin Film Devices and Technology of Tianjin, Engineering Research Center of Thin Film Photo-electronic Technology, Ministry of Education, Institute of Photo-electronic Thin Film Devices and Technology of Nankai University, Tianjin 300350, P.R. China.
² Tianjin Key Laboratory of Film Electronic and Communication Devices School of Electrical and Electronic Engineering, Tianjin University of Technology, Tianjin 300384, China.
³ Tianjin Institute of Power Source, Tianjin 300384, P. R. China.

PMID: 34009933
DOI: 10.1021/acsami.1c00270

Abstract

The surface Ga content for a CIGSe absorber was closely related to variation in the open-circuit voltage (V_OC), while it was generally low on a CIGSe surface fabricated by two-step selenization. In this work, a solution-processed surface treatment based on spin-coating GaCl₃ solution onto a CIGSe surface was applied to increase the Ga content on the surface. XPS, XRD, Raman spectroscopy, and band gap extraction based on the external quantum efficiency response demonstrated that GaCl₃ post deposition treatment (GaCl₃-PDT) can be used to enhance the Ga content on the surface of a CIGSe absorber. Meanwhile, a solution-processed surface treatment with KSCN (KSCN-PDT) was employed to form a transmission barrier for holes by moving the valence band maximum downward and decreasing the interface recombination between the CdS and CIGSe layers. Admittance spectroscopy results revealed that deep defects were passivated by GaCl₃-PDT or KSCN-PDT. By applying the combination of GaCl₃-PDT and KSCN-PDT, a champion device was realized that exhibited an efficiency of 13.5% with an improved V_OC of 610 mV. Comparing the efficiency of the untreated CIGSe solar cells (11.7%), the CIGSe device efficiency with GaCl₃-PDT and KSCN-PDT exhibited 15% enhancement.

Keywords: CIGSe; post deposition treatment; solar cells; solution-processed; surface treatment.