Corrosion-Free Pyridine Derivatives for the Stable Perovskite Solar Cells
Liyuan Han a, Youfeng Yue a, Xing Li a b
a National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305, Japan
b East China University of Science and Technology, 130 Meilong Road, Shanghai, China
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
Proceedings of International Conference Asia-Pacific Hybrid and Organic Photovoltaics (AP-HOPV17)
Yokohama-shi, Japan, 2017 February 2nd - 4th
Organizers: Tsutomu Miyasaka and Iván Mora-Seró
Poster, Xing Li, 117
Publication date: 7th November 2016

Perovskite solar cells (PSCs) based on lead halide perovskite (e.g., CH3NH3PbI3) have recently attracted worldwide attention in the photovoltaic technology field because of their low costs and high efficiency. The power conversion efficiencies (PCEs) of these devices have increased from approximately 4.0 % to 22.0 %. However, the large-scale application of highly efficient PSCs has been restricted by the poor long-term stability, which is induced by several complicated degradation processes, such as photoreaction at TiO2 surface, thermal-instability of perovskite, iodide diffusion at bias, water incursions or corrosion induced by additives in organic hole-transporting materials (HTMs).

Herein, we fabricated mesoscopic PSCs with various pyridine-based additives in 2,2′,7,7′-tetrakis(N,N-di-pmethoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) and compared their photovoltaic performance with that of a 4-tertbutyl pyridine (TBP)-based device. We observed that Lewis-base pyridine additives could strongly enhance the photovoltaic performance of the PSCs. We also confirmed that most of the investigated pyridine derivatives corroded perovskite due to the formation of new complexes with PbI2. This corrosion phenomenon led to chemical decomposition of the perovskite and deteriorated the interface between the perovskite and the HTMs. Most importantly, we found a new additive of pyridine with a long alkyl chain substituted at the o-position chemically stable with no corrosion to perovskite, thereby substantially improving PSC stability.

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