Critical Role of Carrier Cooling Mechanism in WS2/CsPbBr3 Hybrid Nanocomposites for Enhanced Photodetector Performances

Heterostructures and nanocomposites comprising transition metal dichalcogenides (TMDCs) and halide perovskite nanocrystals (NCs) are prominently used in several optoelectronic devices. Hot carriers (HCs) are the charge carriers possessing higher kinetic energy than surrounded thermal distributions. Properly utilizing these HCs by slowing down their cooling mechanism reduces the energy losses in optoelectronic devices. Herein, employing the femtosecond transient absorption spectroscopy (fs-TAS) technique, the slowdown processes of HC relaxations are reported in WS2/CsPbBr3 hybrid-nanocomposites due to the hot-phonon bottleneck. HCs relaxation time increases from approximate to 6 ps in CsPbBr3 NCs to approximate to 10 ps in WS2/CsPbBr3 nanocomposites at an excitation fluence of 17.7 mu J cm(-2). The maximum HCs temperature T-C increased to 1181 K in WS2/CsPbBr3 nanocomposites with an observed T-C of 856 K in pristine NCs. The electron transfer process from NCs to WS2 nanosheets has been observed in these nanocomposites with time component t(2) approximate to 38.0-102.4 ps in pristine NCs and 20.9-66.9 ps in nanocomposites, became faster at excitation-fluence of 17.7-99.8 mu J cm(-2). Furthermore, a significant enhancement in nanocomposite-based photodetector confirmed the efficient charge transfer at the heterojunction, resulting approximate to 400%, approximate to 420%, and approximate to 200% increase in the photocurrent, responsivity, and detectivity, respectively, compared to the pristine devices.