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

Abstract 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, Sb 3+ /Mn 2+ co‐doped Cs 2 NaInCl 6 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. Sb 3+ /Mn 2+ 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 cm 2 )—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.