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

Ganbaatar Tumen-Ulzii; Chuanjiang Qin; Dino Klotz; Matthew R Leyden; Pangpang Wang; Morgan Auffray; Takashi Fujihara; Toshinori Matsushima; Jin-Wook Lee; Sung-Joon Lee; Yang Yang; Chihaya Adachi

doi:10.1002/adma.201905035

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

Adv Mater. 2020 Apr;32(16):e1905035. doi: 10.1002/adma.201905035. Epub 2020 Feb 27.

Authors

Ganbaatar Tumen-Ulzii^{1

2}, Chuanjiang Qin^{1

2}, Dino Klotz³, Matthew R Leyden^{1

2}, Pangpang Wang⁴, Morgan Auffray^{1

2}, Takashi Fujihara⁴, Toshinori Matsushima^{2

3}, Jin-Wook Lee⁵, Sung-Joon Lee⁵, Yang Yang⁵, Chihaya Adachi^{1

2

3

4}

Affiliations

¹ Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan.
² Japan Science and Technology Agency (JST), ERATO, Adachi Molecular Exciton Engineering Project, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan.
³ International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan.
⁴ Institute of Systems, Information Technologies and Nanotechnologies (ISIT), Fukuoka Industry-Academia Symphonicity (FiaS), 4-1 Kyudaishinmachi, Nishi, Fukuoka, 819-0388, Japan.
⁵ Department of Materials Science and Engineering and California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA.

PMID: 32104961
DOI: 10.1002/adma.201905035

Abstract

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.

Keywords: perovskite solar cells; photolysis of PbI2; stability; unreacted PbI2.

Abstract

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