Near‐Infrared Photoresponse of One‐Sided Abrupt MAPbI3/TiO2 Heterojunction through a Tunneling Process |
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| Authors: | Keyou Yan Zhanhua Wei Tiankai Zhang Xiaoli Zheng Mingzhu Long Zefeng Chen Weiguang Xie Teng Zhang Yuda Zhao Jianbin Xu Yang Chai Shihe Yang |
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| Affiliation: | 1. Department of Chemistry, The Hong Kong University of Science and Technology, Kowloon, Hong Kong;2. Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong;3. Siyuan Laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Department of Physics, Jinan University, Guangzhou, Guangdong, China;4. Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong |
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| Abstract: | 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/TiO2 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 TiO2 region (<5 nm), to the N‐type TiO2 electrode. The trap states inject carriers into TiO2 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. |
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| Keywords: | carbon counter electrodes infrared absorption perovskites photodetection tunneling |
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