In Situ Room-Temperature Synthesis of All-Colloidal Quantum Dot CsPbBr3–PbS Heterostructures

In optoelectronics, all-colloidal quantum dot (all-CQD) heterostructures featuring processability and extending the functionalities of individual quantum dots (QDs) have garnered significant attention. Particularly, perovskite and chalcogenide QD heterostructures present a compelling platform for integrating visible- and near-infrared spectral responses through effective carrier transfer. However, a lack of controllable and low-cost synthesis methodologies currently curtails the development and application of such intricate structures. Herein, we report a facile and replicable in situ room-temperature synthesis approach for yielding spectrally tunable, low-cost processing all-CQD CsPbBr3–PbS heterostructures. This approach utilizes the controllable growth and high surface reactivity of amine-free CsPbBr3 QDs, together with a highly reactive sulfur source, to facilitate the in situ formation of heterostructures at room temperature. Our fabricated all-CQD CsPbBr3–PbS heterostructures possess excellent processability and showcase sustainable dual emission in both visible and infrared spectra. The control over which is finely tuned through the manipulation of the Pb/S ratio. Transient absorption spectroscopy reveals ultrafast interdot carrier injection (initiating in less than ∼1 ps) from the perovskite to PbS within the heterostructures, allowing the photons absorbed by CsPbBr3 QDs to be efficiently provided for PbS's infrared emission. Based on their low-cost processability, we debuted their application in short-wave infrared imaging by harnessing ultraviolet light. We attained a resolution with a low response threshold of 18 mW/cm2 (365 nm), which approaches the International Electrotechnical Commission's safety limit (10 mW/cm2), significantly surpassing the performance of standalone PbS QDs. Our research presents a reproducible technique for creating controllable and low-cost processing all-CQD heterostructures, which sets the stage for future developments in their application.