Fabrication of flexible Cs2AgBiBr6 photodetector by using TiO2 nanorods electron-transport layer

Abstract

In this work, we demonstrate a perovskite photodetector with transferable TiO2 electron transfer layer (ETL) formed by chemical lift off (CLO) method with a metal buffer layer. TiO2 nanorods (NRs) were grown by hydrothermal method on Cu-buffer layer /Si(100) substrates. During the growth process of TiO2 NRs in solution, Cu buffer buffer layer is removed by hydrochloric acid at initial stage, and the suspended both sides of seed layer can sustain the growth of TiO2 NRs in a separate form and can be easily separated by PET. The TiO2 NRs transferred onto the ITO coated PET substrate as a ETL for flexible Cs2AgBiBr6(CABB) perovskite photodetectors. The fabricated PD has 405nm operating wavelength under an external bias voltage of -0.2V with an outstanding on/off ratio of 484, photoresponsivity (R) of 18.7 mA/W, and a detectivity (D*) of 3.11 ×1010 Jones. Since ETL's can improve electron transfer efficiency, devices with Ni-TiO2 ETL and CuTiO2 ETL have 41.2 and 65.4 times higher on/off ratio and 9.7 and 16.9 times higher detectivity than CABB single devices.Our suggested transferable TiO2 NRs could pave the way to improve efficiency of flexible optoelectronic devices requiring heterostructures.