High-photoresponse mixed-dimensional CuOx/WSe2 p-type phototransistor with van der Waals interface

Mixed-dimensional heterostructures, which utilize the complementary advantages of diverse materials, hold great promise for high-performance photodetectors. However, p-type photodetection is constrained by the scarcity of suitable photosensitive materials and challenges in interface engineering, particularly over-coupling at the hetero-interface, which significantly impacts detection performance. In this work, we present a p-type CuOx/WSe2 phototransistor that achieves both high responsivity and broad bandwidth. Using CuOx nanoparticles with abundant copper vacancies for broadband light absorption and two-dimensional WSe2 as a high-mobility channel, this device demonstrates an exceptional responsivity of up to 1.8 × 105 A/W across wavelengths from 365 to 810 nm. The high performance originates from hole injection from defect-rich CuOx into WSe2, combined with electron trapping in vacancy states. The weak van der Waals interaction at the interface effectively decouples the optical absorption (in CuOx) from charge transport (in WSe2), enabling high gain without sacrificing response speed.