Tailoring environment-friendly copper chalcogenide quantum dots for red light-emitting diodes

Colloidal copper chalcogenide quantum dots (QDs) have demonstrated low-toxicity, large absorption coefficients and high photoluminescence quantum yield (PLQY), holding great promise for high-performing QDs light-emitting diodes (QLEDs). However, their intrinsic Cu-related vacancies/defects could induce multiple sub-bands emission with broad full width at half maximum (FWHM), severely limiting the luminescence efficiency and color purity for display application. Herein, eco-friendly CuInGaS-ZnInS-ZnS (CIGS-ZIS-ZnS) QDs with passivated interfacial defects and improved donor-acceptor pair (DAP) radiative recombination were developed, showing a PLQY up to 95.3% at 632 nm with a relatively narrow FWHM of 78 nm. As a proof-of-concept, the fabricated CIGS-ZIS-ZnS QLEDs delivered a maximum external quantum efficiency (EQE) of ∼5% that is significantly higher than the control CIGS-ZnS QLED device (1.1%). These findings suggest that the rational design of heterostructured QDs is promising to resolve the long-standing trade-off between high PLQY and narrow FWHM in copper chalcogenide QDs for color-pure display application. • Environment-friendly CuInGaS-ZnInS-ZnS QDs with a precisely engineered interfacial layer are developed. • As-synthesized QDs exhibit a high PLQY of 95.3% with a narrow FWHM of 78 nm. • The ZnInS layer effectively suppresses interfacial defect states for enhanced DAP radiative recombination. • The fabricated red QLED delivers an EQE of ∼5%, outperforming most copper chalcogenide QLED devices.