Charge Carrier Dynamics in 6 nm CsPbBr3–Pb4S3Br2 Heterostructured Quantum Dots

Abstract

Epitaxial CsPbBr3–Pb4S3Br2 heteronanocrystals (HNCs) with coherent interfaces are promising for wave function modulation. Herein, we synthesize 6 nm CsPbBr3–Pb4S3Br2 heterostructured quantum dots (HQDs) in a ZnBr2-stabilized Br–-rich system and probe their interfacial charge transfer via steady-state absorption, photoluminescence (PL), time-resolved PL (TRPL) and transient absorption spectroscopy (TAS). Relative to pure CsPbBr3 QDs, the 6 nm HQDs show PL quenching and faster ground-state bleaching (GSB) recovery. Reducing size from 15 nm HNCs to 6 nm HQDs induces a prominent blue shift and weakened amplitude of the GSB signal of Pb4S3Br2 domain, verifying efficient charge carrier spatial separation: electrons are distributed in the CsPbBr3 domain while holes accumulate in the Pb4S3Br2 domain. Benefiting from such separation, photoconductive devices based on 6 nm HQDs achieve photocurrent 3 orders of magnitude higher than pure CsPbBr3 QD devices. This study expands the regulation strategies for CsPbBr3–Pb4S3Br2 heterostructures beyond facet and morphology control.