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

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In this work, a flexible perovskite photodetector is demonstrated with a transferable TiO 2 nanorod (NR) as an electron transport layer (ETL). The TiO 2 NRs are grown by the hydrothermal method on Ni metal buffer layer/Si (100) substrates. During the growth process of TiO 2 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 TiO 2 NRs in both the top and bottom directions. The successfully grown TiO 2 NRs are now transferred onto an ITO‐coated PET substrate as an ETL for the flexible Cs 2 AgBiBr 6 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 × 10 4 , photoresponsivity ( R ) of 0.666 A W −1 , and a detectivity ( D * ) of 9.29 × 10 12 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 TiO 2 NRs can improve the efficiency of flexible optoelectronic devices that require synergistic electron transfer effects by using heterostructures with TiO 2 nanostructures.