Nontoxic CuInS₂/ZnS Colloidal Quantum Dots for White Light-Emitting Diodes

CuInS₂ quantum dots (CIS QDs), with tunable photoluminescence spanning from the visible to near-infrared (NIR) region, hold significant potential for consumer electronics and bioimaging due to their favorable photophysical properties and absence of toxic elements. However, their intrinsic lack of short-wavelength emission has hindered their use in white light-emitting applications. Herein, we report a facile synthesis of zinc-acetate-oleylamine (Zn-Ac-OAm) and oleylamine (OAm)-coencapsulated CIS/ZnS QDs that deliver full-spectrum sunlight-like emissions, characterized by a distinct 455 nm peak and an ultrabroad full width at half-maximum (fwhm) of 241 nm. The Zn-Ac-OAm emitter produces blue-green fluorescence, effectively compensating for the short-wavelength deficiency of the CIS/ZnS QDs. More importantly, strong interactions between Zn-Ac-OAm and CIS/ZnS QDs enable efficient energy transfer within coencapsulated structures. As a proof of concept, white light-emitting diodes (WLEDs) fabricated using these coencapsulated CIS/ZnS QDs exhibit excellent photophysical performance, achieving a high color rendering index (CRI) of 92.1 and external quantum efficiency (EQE) of 7.2%. This coencapsulation strategy, together with the elucidated photophysical mechanisms, provides viable pathways for extending the application of long-wavelength-emitting nanomaterials in next-generation lighting and display technologies.