High-Performance and Stability of CsPbBr₃/WSe₂ Hybrid Photodetectors Functionalized Using Quaternary Ammonium Ligands

The 2D–0D hybrid photodetector, with its special structure, high sensitivity, and wavelength tunability, is reported as a promising candidate system for optoelectronic devices. As research on hybrid lead halide perovskite quantum dots (PQDs) has progressed, PQDs with high photoluminescence (PL) quantum yield and excellent absorption properties are increasingly applied in optoelectronic devices; however, PQD stability remains one of the biggest limitations on device performance. Here, it is reported that the properties and stability of the hybrid photodetectors are improved by surface passivation using the quaternary ammonium ligand (didodecyldimethylammonium bromide, DDAB). The average carrier lifetime of DDAB treated CsPbBr₃ PQDs (DDAB-capped PQDs) is longer than that of pristine CsPbBr₃ PQDs by 6.68–14.88 ns. It is confirmed that the durability against water is reduced by only 25.8% at PL intensity and is preserved for more than 16 h. A 2D–0D hybrid photodetector is then fabricated by deposition of DDAB-capped PQDs on the WSe₂ field-effect transistor device for a high-performance photodetector. The WSe₂/DDAB-capped PQD hybrid photodetector exhibits an enhanced responsivity of 1.4 × 10³ A W⁻¹ and an improved detectivity of 3.1 × 10¹³ Jones under 40.0 µW cm⁻² of a 405 nm laser.