High-Efficiency Flexible Cs2AgBiBr6-Based Visible Photodetector with Transferable TiO2 Nanorod Electron-Transport Layer

Abstract

In this work, a flexible perovskite photodetector is demonstrated with a transferable TiO2 nanorod (NR) as an electron transport layer (ETL). The TiO2 NRs are grown by the hydrothermal method on Ni metal buffer layer/Si (100) substrates. During the growth process of TiO2 NRs in solution, the Ni sacrificial buffer layer is removed by hydrochloric acid in the initial stage. The resulting suspended seed layer can then sustain the growth of TiO2 NRs in both the top and bottom directions. The successfully grown TiO2 NRs are now transferred onto an ITO-coated PET substrate as an ETL for the flexible Cs2AgBiBr6 perovskite photodetectors. The fabricated photodetector operates under a wavelength of 405 nm, and at an external bias voltage of −0.3 V, it exhibits an outstanding performance with an on/off ratio of 1.23 × 104, photoresponsivity (R) of 0.666 A W−1, and a detectivity (D*) of 9.29 × 1012 Jones. In terms of flexibility, the optoelectronic performance of each device is well kept within 5% after 300 bending test cycles with a radius of 1 cm. The suggested transferable TiO2 NRs can improve the efficiency of flexible optoelectronic devices that require synergistic electron transfer effects by using heterostructures with TiO2 nanostructures.