Ti₃C₂T_x MXene‐Assisted CuBO₂ Hole Transport Layer for High‐Performance Ultraviolet Photodetectors

Abstract The efficient separation and extraction of holes can be attributed to the favorable properties possessed by the hole transport layer (HTL). Herein, a novel solution‐processable hybrid HTL based on CuBO₂ and Ti₃C₂T_x MXene (CuBO₂@MXene) is developed to enhance the performance of ultraviolet photodetectors (UV PDs). By optimizing the ratio of Ti₃C₂T_x MXene to CuBO₂, the optimized responsivity and detectivity of the UV PDs based on the composite HTL have achieved 184 mA W⁻¹ and 2.88 × 10¹³ cm Hz^1/2 W⁻¹ in self‐powered mode, respectively, and even up to 3.25 × 10⁴ mA W⁻¹ at −1.5 V. This significant improvement in device performance can be attributed to the interlaced architecture of CuBO₂@MXene, which ameliorates hole mobility and charge extraction capability while reducing the trap state density of the HTL. The built‐in electric field of the TiO₂/CuBO₂ heterojunction is strengthened by the incorporation of Ti₃C₂T_x MXene, thereby significantly reinforcing the photovoltaic effect. Moreover, the lower thermal conductivity of CuBO₂@MXene suppresses its pyroelectric effect, weakening the blocking effect of the thermoelectric potential on hole transport and ultimately leading to a remarkable boost in the output current. These results indicate the promising potential of the hybrid CuBO₂@MXene HTL for constructing high‐performance optoelectronic devices.