Dual Effects of Slow Recrystallization and Defects Passivation Achieve Efficient Tin‐Based Perovskite Solar Cells with Good Stability Up to One Year

• Published in: Advanced functional materials Vol. 33; no. 12
• Main Authors: Zheng, Chunqiu, Qiu, Peng, Zhong, Shoudeng, Luo, Xinyi, Wu, Shengcheng, Wang, Qiwei, Gao, Jinwei, Lu, Xubing, Gao, Xingsen, Shui, Lingling, Wu, Sujuan, Liu, Jun‐Ming
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.03.2023
• Subjects: Charge transfer; Circuits; Crystal defects; defect passivation; Energy conversion; Materials science; one year; Optoelectronics; Oxidation; Perovskites; Photomicrographs; Photovoltaic cells; Recrystallization; Solar cells; Stability; thiourea; Thioureas; tin‐based perovskite solar cells; Toxicity
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202212106

Tin‐based perovskite solar cells (TPSCs) have become a star candidate in lead‐free perovskite cells due to their excellent optoelectronic properties and low toxicity. However, there are a lot of problems such as uncontrollable crystallizationprocess, easy oxidation of Sn2+ and high defect density have not been completely resolved in TPSCs. Here, the thiourea (TU) and amidine thiourea (ASU) are added into the perovskite precursor to regulate the microstructure, inhibit the oxidation of Sn2+ and promote charge transfer. The characterization results demonstrate that the TU additive can not only improve the micrograph, crystallinity and antioxidant, but also significantly induce recrystallization and passivate trap states. Thus, the TPSCs with TU (TU‐modified TPSCs) show a significantly higher power conversion efficienc (PCE) and better stability than those of the TPSCs with ASU (ASU‐modified PSCs) and reference TPSCs. After stored in N2 atmosphere for 8 months, the unencapsulated TU‐modified PSCs achieve a champion PCE of 10.9% with an open‐circuit voltage of 0.79 V. Furthermore, the unsealed TU‐modified PSCs can maintain 115% of its initial efficiency after stored in N2 atmosphere for one year. This is the longest lifetime of unencapsulated pure TPSCs in N2 atmosphere. Thiourea and amidine thiourea additives are used to improve the film quality, inhibit the oxidation of Sn2+ to Sn4+ and slowly passivate the trap states, respectively. Significantly, through the dual effects on slow recrystallization and defect passivation, thiourea‐modified device exhibits a champion efficiency of 10.9% and maintains 115% of its initial efficiency after stored for 1 year.