O, N co-doped CuCrO2 as efficient hole transport layer for high-performance ultraviolet photodetectors

Abstract

The optoelectronic properties and film-formation characteristics of CuCrO2 are optimized through oxygen (O) and nitrogen (N) co-doping using the space-limited domain annealing method in ambient air. After O, N co-doping at 100 °C, the conductivity of CuCrO2 is enhanced due to a decrease in trap-state density and an increase in hole concentration, thereby facilitating carrier transport. With a work function (WF) of 5.24 eV and an electron affinity (χ) of 2.29 eV, the CuCrO2 films serves as both a hole transport layer (HTL) and an electron-blocking layer, playing a pivotal role in enhancing photogenerated holes extraction while suppressing nonradiative charge recombination at the heterojunction interface. Consequently, the responsivity and detectivity of the device with FTO/TiO2 NRs/O, N co-doped CuCrO2/Au structure reach 188 mA W−1 and 3.14 × 1013 cm Hz1/2 W−1 in self-powered mode, respectively. Simultaneously, the rise/decay time is reduced to just 31.2/32.1 ns. Furthermore, after applying a bias of − 2 V, the photodetector demonstrates significantly improved performance with a responsivity of up to 5 × 105 mA/W (365 nm, 0.97 mW cm−2) and an apparent quantum efficiency of ∼30,000%. These results highlight the promising potential of utilizing O, N co-doped CuCrO2 HTL for constructing high-performance optoelectronic devices.