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A Band‐Edge Potential Gradient Heterostructure to Enhance Electron Extraction Efficiency of the Electron Transport Layer in High‐Performance Perovskite Solar Cells
Author(s) -
Hou Yu,
Chen Xiao,
Yang Shuang,
Li Chunzhong,
Zhao Huijun,
Yang Hua Gui
Publication year - 2017
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201700878
Subject(s) - heterojunction , materials science , perovskite (structure) , optoelectronics , energy conversion efficiency , electron , layer (electronics) , electron mobility , photoelectric effect , charge carrier , nanotechnology , chemical engineering , physics , quantum mechanics , engineering
As the key component in efficient perovskite solar cells, the electron transport layer (ETL) can selectively collect photogenerated charge carriers produced in perovskite absorbers and prevent the recombination of carriers at interfaces, thus ensuring a high power conversion efficiency. Compared with the conventional single‐ or dual‐layered ETLs, a gradient heterojunction (GHJ) strategy is more attractive to facilitate charge separation because the potential gradient created at an appropriately structured heterojunction can act as a driving force to regulate the electron transport toward a desired direction. Here, a SnO 2 /TiO 2 GHJ interlayer configuration inside the ETL is reported to simultaneously achieve effective extraction and efficient transport of photoelectrons. With such an interlayer configuration, the GHJs formed at the perovskite/ETL interface act collectively to extract photogenerated electrons from the perovskite layer, while GHJs formed at the boundaries of the interconnected SnO 2 and TiO 2 networks throughout the entire ETL layer can extract electron from the slow electron mobility TiO 2 network to the high electron mobility SnO 2 network. Devices based on GHJ ETL exhibit a champion power conversion efficiency of 18.08%, which is significantly higher than that obtained from the compact TiO 2 ETL constructed under the comparable conditions.