Near-UV Phototransistors Based on an All-Inorganic Lead-Free Cs<sub>3</sub>Cu<sub>2</sub>I<sub>5</sub>/CuTCNQ Hierarchical Heterostructure
Zhi Jiang, Hezhuang Liu, Jihua Zou, Yixuan Huang, Zhaoquan Xu, Caihong Li, Desheng Liu
Abstract
With the rapid advances in metal halide perovskite optoelectronics, eliminating toxic lead from perovskites has been an urgent demand. However, state-of-the-art lead-free perovskite photodetectors are still challenged with issues of low photoresponse, poor stability, etc. Here, all-inorganic lead-free perovskite (Cs3Cu2I5) single crystals that possess good stability under air exposure are synthesized via a facile solid reaction method. Meanwhile, a higher photoluminescence quantum yield of 95.2% and a prolonged carrier lifetime of 1.127 μs are obtained by further optimizing the synthesis. Benefiting from the polyporous surface and hollow structure of Cu-7,7,8,8-tetracyanoquinodimethane (CuTCNQ) microtubes, more Cs3Cu2I5 nanocrystals can adhere on the innershell and outershell of CuTCNQ-15 microtubes. This unique structure contributes to the improved efficiency of utilizing incident light and promotes charge carrier generation and transportation. As a result, the hierarchical CuTCNQ/Cs3Cu2I5 (hollow microtube/nanocrystal) heterostructure phototransistor exhibits a high responsivity of 88.36 A W–1 and a large detectivity of 1.66 × 1012 Jones. The proposed lead-free perovskites and mixed-dimensional heterojunctions are promising for sensitive light detection.