Quantum dot-based photo energy storage and visible-light sensitization of polyoxometalate systems

Quantum-dot light-emitting diodes (QLEDs) are being developed into next-generation display devices because of their high color saturation, tunability of dispersion and structural durability. Aside from displays, quantum dots (QDs) feature importantly in energy studies owing to their photoinduced charge transfer characteristics. Specifically, the integration of QDs with molecular electron acceptors has been highlighted for solar energy conversion and photocatalysis. Among different candidates, CuInS2 quantum dots (QDs) have shown considerable potential in sensitizing polyoxometalates (POMs) upon visible-light excitation. POMs are redox-active clusters that can accumulate several electrons without concomitant structure degradation and thus function as very good electron reservoirs. Photoluminescence quenching and reduction of lifetime experiments validate that photoexcited electrons formed in CuInS2 QDs are effectively transferred to POMs, including SiW12O40 and W10O32, usually with the assistance of stabilizers like polypyrrole or surfactants. Here, QDs serve as light-harvesting antennas, and POMs as charge-storage units. The synergy between the two systems displays both photoenergy storage and visible-light sensitization. During illumination, POMs trap the photogenerated electrons from QDs; in dark conditions, the stored charges are discharged via redox reactions like the reduction of noble-metal ions. This synergy underscores the potential of QDs–POM assemblies for application in photocatalysis, energy conversion and future solar technologies.