Near-Unity Quantum Yield Conductive Inks of Lead-Free Double Perovskite Quantum Dots for White LEDs.

Double perovskite quantum dots (QDs) with self-trapped exciton emission provide an eco-friendly route to broadband white-light generation. Yet severe charge losses arising from trap-mediated recombination and inefficient carrier transport remain major obstacles to their integration into electroluminescent devices. Here, Sb3+/Mn2+ co-doped Cs2NaInCl6 QD inks are reported that enable the fabrication of defect-suppressed, conductive QD films with low charge transport and hole-injection barriers in light-emitting diode (LED) devices. Sb3+/Mn2+ co-doping not only induces white emission but also suppresses cation disorder, leading to near-unity photoluminescence quantum yield. Moreover, replacing long-chain ligands with short-chain 2-ethylhexanoic acid and 3,3-diphenylpropylamine chloride enhances the film conductivity by nearly 20-fold and induces a favorable band alignment with the poly(9-vinylcarbazole):poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine] hole transport layer, hereby reducing the injection barrier by 0.4 eV. These improvements enable an LED external quantum efficiency of 0.91% (0.05 cm2)-the highest reported for double perovskite QDs and nearly 1.3 the previous record. It is anticipated that this work provides a viable route toward overcoming the key limitations of double perovskite electroluminescence and advancing eco-friendly solid-state lighting.