Near-Infrared Photoresponse of One-Sided Abrupt MAPbI₃/TiO₂ Heterojunction through a Tunneling Process

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• 作者：Keyou Yan ; Zhanhua Wei ; Tiankai Zhang ; Xiaoli Zheng ; Mingzhu Long ; Zefeng Chen ; Weiguang Xie ; Teng Zhang ; Yuda Zhao ; Jianbin Xu ; Yang Chai and Shihe Yang
• 刊名：Advanced Functional Materials
• 出版年：2016
• 出版时间：December 13, 2016
• 年：2016
• 卷：26
• 期：46
• 页码：8545-8554
• 全文大小：2212K
• ISSN：1616-3028

文摘

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.