Hysteresis-free low-temperature-processed planar perovskite solar cells with 19.1% efficiency

• Published in: Energy & environmental science 2016-07, Vol.9 (7), p.2262-2266
• Main Authors: Yoon, Heetae, Kang, Seong Min, Lee, Jong-Kwon, Choi, Mansoo
• Format: Article
• Language: English
• Subjects: Buckminsterfullerene; Devices; Fullerenes; Grain boundaries; Perovskites; Photoelectric effect; Photovoltaic cells; Solar cells
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/c6ee01037g

Hysteresis-free, highly efficient and stable perovskite solar cells processed at low temperatures are strongly demanded to realize flexible or perovskite-based tandem solar cells. Here, we report a hysteresis-free planar CH 3 NH 3 PbI 3 perovskite solar cell with a power conversion efficiency of 19.1% using a room-temperature vacuum-processed C 60 electron transport layer (ETL) without the hole blocking layer. By optimizing the thickness of the C 60 layer, the highly homogeneous, uniform, and dense ETL with a thickness of 35 nm is found to not only passivate the grain boundaries and surfaces of the perovskite layer, but also enhance charge transport properties. Thus, the C 60 layer deposited on perovskites eliminates the photocurrent hysteresis and improves the cell efficiency. Also, compared to the device adopting the C 60 and bathocuproine (BCP) combination, the one with the C 60 layer without the BCP layer shows better performance due to enhanced electron extraction properties. Furthermore, for the first time, we have demonstrated a hysteresis-free flexible perovskite solar cell using the C 60 ETL on a polyethylene naphthalate (PEN) substrate with 16.0% efficiency. Hysteresis-free and highly efficient CH 3 NH 3 PbI 3 perovskite solar cells employing a compact C 60 material as an electron transport layer have been developed for the first time using both rigid glass and plastic substrates.