Graded Heterojunction Improves Wide-Bandgap Perovskite for Highly Efficient 4-Terminal Perovskite/Silicon Tandem Solar Cells

Wenming Chai; Lindong Li; Weidong Zhu; Dazheng Chen; Long Zhou; He Xi; Jincheng Zhang; Chunfu Zhang; Yue Hao

doi:10.34133/research.0196

Graded Heterojunction Improves Wide-Bandgap Perovskite for Highly Efficient 4-Terminal Perovskite/Silicon Tandem Solar Cells

Research (Wash D C). 2023 Jul 17:6:0196. doi: 10.34133/research.0196. eCollection 2023.

Authors

Wenming Chai¹, Lindong Li¹, Weidong Zhu^{1

2

1}, Dazheng Chen^{1

2}, Long Zhou^{1

2}, He Xi¹, Jincheng Zhang¹, Chunfu Zhang^{1

2

1}, Yue Hao¹

Affiliations

¹ State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology & Shaanxi Joint Key Laboratory of Graphene, School of Microelectronics, Xidian University, Xi'an, Shaanxi 710071, China.
² Xi'an Baoxin Solar Technology Co., Ltd., Xi'an, 710071, China.

Abstract

Wide-bandgap (WBG) perovskite solar cells (PSCs) are essential for highly efficient and stable silicon/perovskite tandem solar cells. In this study, we adopted a synthetic strategy with lead thiocyanate (Pb(SCN)₂) additive and methylammonium chloride (MACl) posttreatment to enhance the crystallinity and improve the interface of WBG perovskite films with a bandgap of 1.68 eV. The excessive PbI₂ was formed at grain boundaries and converted into MAPbI_3-xCl_x perovskites, which are utilized to form the graded heterojunction (GHJ) and compressive strain. This is beneficial for passivating nonradiative recombination defects, suppressing halide phase segregation, and facilitating carrier extraction. Subsequently, the device with GHJ delivered a champion efficiency of 20.30% and superior stability in ambient air and under 85 °C. Finally, we achieved a recorded efficiency of 30.91% for 4-terminal WBG perovskite/TOPCon tandem silicon solar cells. Our findings demonstrate a promising approach for fabricating efficient and stable WBG PSCs through the formation of GHJ.