Molecule-induced ripening control in perovskite quantum dots for efficient and stable light-emitting diodes

Perovskite quantum dots (QDs) show an excellent application perspective in semiconductor optoelectronic devices. However, problems of ligand loss during the growth, purification, film formation, and storage process always induce the aggregation and ripening of QDs, adversely affecting QDs' and QD-based devices' performance. Here, we use a bidentate molecule to control ripening toward a notable performance boost in CsPbI₃ QDs. The strong interaction between QDs and the bidentate molecules maintains stable surface states of QDs, inhibiting QDs' undesirable ripening and generation of defects. We fabricate QD-based light-emitting diodes (LEDs) with a maximum external quantum efficiency (EQE) of 26.0% at 686 nm and an operating half-life of 10,587 hours at an initial radiance of 190 mW sr^-1 m^-2 (equivalent to a luminance of 100 cd m^-2 for green perovskite LEDs). Benefiting from the high storability of the target QDs, the as-fabricated devices based on the QD solution storing for 1 month show a maximum EQE of 21.7% (20.3% for 3 months).