Energy Band Alignment by Solution-Processed Aluminum Doping Strategy toward Record Efficiency in Pulsed Laser-Deposited Kesterite Thin-Film Solar Cell

Tong Wu; Juguang Hu; Shuo Chen; Zhuanghao Zheng; Michel Cathelinaud; Hongli Ma; Zhenghua Su; Ping Fan; Xianghua Zhang; Guangxing Liang

doi:10.1021/acsami.2c22174

Energy Band Alignment by Solution-Processed Aluminum Doping Strategy toward Record Efficiency in Pulsed Laser-Deposited Kesterite Thin-Film Solar Cell

ACS Appl Mater Interfaces. 2023 Mar 7. doi: 10.1021/acsami.2c22174. Online ahead of print.

Authors

Tong Wu^{1

2}, Juguang Hu¹, Shuo Chen¹, Zhuanghao Zheng¹, Michel Cathelinaud¹, Hongli Ma², Zhenghua Su¹, Ping Fan¹, Xianghua Zhang², Guangxing Liang¹

Affiliations

¹ Shenzhen Key Laboratory of Advanced Thin Films and Applications, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, Guangdong, P. R. China.
² CNRS, ISCR (Institut des Sciences Chimiques de Rennes) UMR 6226, Univ Rennes, Rennes F-35000, France.

PMID: 36880785
DOI: 10.1021/acsami.2c22174

Abstract

Kesterite-based Cu₂ZnSnS₄ (CZTS) thin-film photovoltaics involve a serious interfacial dilemma, leading to severe recombination of carriers and insufficient band alignment at the CZTS/CdS heterojunction. Herein, an interface modification scheme by aluminum doping is introduced for CZTS/CdS via a spin coating method combined with heat treatment. The thermal annealing of the kesterite/CdS junction drives the migration of doped Al from CdS to the absorber, achieving an effective ion substitution and interface passivation. This condition greatly reduces interface recombination and improves device fill factor and current density. The J_SC and FF of the champion device increased from 18.01 to 22.33 mA cm^-2 and 60.24 to 64.06%, respectively, owing to the optimized band alignment and remarkably enhanced charge carrier generation, separation, and transport. Consequently, a photoelectric conversion efficiency (PCE) of 8.65% was achieved, representing the highest efficiency in CZTS thin-film solar cells fabricated by pulsed laser deposition (PLD) to date. This work proposed a facile strategy for interfacial engineering treatment, opening a valuable avenue to overcome the efficiency bottleneck of CZTS thin-film solar cells.

Keywords: carrier transport; energy band alignment; heterojunction heat treatment; kesterite solar cell; pulsed laser deposition.