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

The optoelectronic properties and film-formation characteristics of CuCrO ₂ 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 CuCrO ₂ is enhanced due to a decrease in trap-state density and an increase in hole concentration, thereby facilitating carrier transport. With a work function ( W _F ) of 5.24 eV and an electron affinity ( χ) of 2.29 eV, the CuCrO ₂ 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/TiO ₂ NRs/O, N co-doped CuCrO ₂/Au structure reach 188 mA W ⁻¹ and 3.14 × 10 ¹³ cm Hz ^1/2 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 × 10 ⁵ 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 CuCrO ₂ HTL for constructing high-performance optoelectronic devices.