Detrimental Effect of Unreacted PbI2 on the Long‐Term Stability of Perovskite Solar Cells

• Published in: Advanced materials (Weinheim) Vol. 32; no. 16; pp. e1905035 - n/a
• Main Authors: Tumen‐Ulzii, Ganbaatar, Qin, Chuanjiang, Klotz, Dino, Leyden, Matthew R., Wang, Pangpang, Auffray, Morgan, Fujihara, Takashi, Matsushima, Toshinori, Lee, Jin‐Wook, Lee, Sung‐Joon, Yang, Yang, Adachi, Chihaya
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.04.2020
• Subjects: Decomposition reactions; Degradation; Illumination; Iodine; Materials science; perovskite solar cells; Perovskites; Photodecomposition; photolysis of PbI2; Photovoltaic cells; Solar cells; Stability; unreacted PbI2
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.201905035

Excess/unreacted lead iodide (PbI2) has been commonly used in perovskite films for the state‐of‐the‐art solar cell applications. However, an understanding of intrinsic degradation mechanisms of perovskite solar cells (PSCs) containing unreacted PbI2 has been still insufficient and, therefore, needs to be clarified for better operational durability. Here, it is shown that degradation of PSCs is hastened by unreacted PbI2 crystals under continuous light illumination. Unreacted PbI2 undergoes photodecomposition under illumination, resulting in the formation of lead and iodine in films. Thus, this photodecomposition of PbI2 is one of the main reasons for accelerated device degradation. Therefore, this work reveals that carefully controlling the formation of unreacted PbI2 crystals in perovskite films is very important to improve device operational stability for diverse opto‐electronic applications in the future. Degradation of perovskite solar cells with excess PbI2 is investigated. Excess PbI2 in perovskite films undergoes photodecomposition (photolysis) under illumination, which produces lead and iodine and accelerates the degradation of PSCs.