Efficient Homojunction Tin Perovskite Solar Cells Enabled by Gradient Germanium Doping

Zhenzhu Zhao, Mulin Sun, Yuyang Ji, Kaitian Mao, Zongming Huang, Chengjian Yuan, Yuqian Yang, Honghe Ding, Yingguo Yang, Yu Li*, Wenjing Chen*, Junfa Zhu, Jing Wei, Jixian Xu, Watcharaphol Paritmongkol, Antonio Abate, Zhengguo Xiao, Lixin He*, Qin Hu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

P-type self-doping is known to hamper tin-based perovskites for developing high-performance solar cells by increasing the background current density and carrier recombination processes. In this work, we propose a gradient homojunction structure with germanium doping that generates an internal electric field across the perovskite film to deplete the charge carriers. This structure reduces the dark current density of perovskite by over 2 orders of magnitude and trap density by an order of magnitude. The resultant tin-based perovskite solar cells exhibit a higher power conversion efficiency of 13.3% and excellent stability, maintaining 95% and 85% of their initial efficiencies after 250 min of continuous illumination and 3800 h of storage, respectively. We reveal the homojunction formation mechanism using density functional theory calculations and molecular level characterizations. Our work provides a reliable strategy for controlling the spatial energy levels in tin perovskite films and offers insights into designing intriguing lead-free perovskite optoelectronics.

Original languageEnglish
Pages (from-to)5513-5520
Number of pages8
JournalNano Letters
Volume24
Issue number18
DOIs
Publication statusPublished - 8 May 2024

Keywords

  • gradient homojunction
  • perovskite solar cells
  • tin-based perovskite

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