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Near‐Infrared Photoresponse of One‐Sided Abrupt MAPbI 3 /TiO 2 Heterojunction through a Tunneling Process
Author(s) -
Yan Keyou,
Wei Zhanhua,
Zhang Tiankai,
Zheng Xiaoli,
Long Mingzhu,
Chen Zefeng,
Xie Weiguang,
Zhang Teng,
Zhao Yuda,
Xu Jianbin,
Chai Yang,
Yang Shihe
Publication year - 2016
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.201602736
Subject(s) - quantum tunnelling , materials science , heterojunction , optoelectronics , perovskite (structure) , infrared , photovoltaics , semiconductor , charge carrier , photovoltaic system , optics , physics , chemistry , ecology , biology , crystallography
Trap states in semiconductors usually degrade charge separation and collection in photovoltaics due to trap‐mediated nonradiative recombination. Here, it is found that perovskite can be heavily doped in low concentration with non‐ignorable broadband infrared absorption in thick films and their trap states accumulate electrons through infrared excitation and hot carrier cooling. A hybrid one‐sided abrupt perovskite/TiO 2 p‐N heterojunction is demonstrated that enables partial collection of these trap‐filled charges through a tunneling process instead of detrimental recombination. The tunneling is from broadband trap states in the wide depleted p‐type perovskite, across the barrier of the narrow depleted TiO 2 region (<5 nm), to the N‐type TiO 2 electrode. The trap states inject carriers into TiO 2 through tunneling and produce around‐unity peak external quantum efficiency, giving rise to near‐infrared photovoltaics. The near‐infrared response allows photodetecting devices to work in both diode and conductor modes. This work opens a new avenue to explore the near‐infrared application of hybrid perovskites.