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Defect suppression via precursor additives is crucial to achieving high efficiency and stable perovskite quantum dot light‐emitting diodes (Pe‐QLEDs). Herein, a strategy using 4‐dodecylbenzenesulfonic acid (DBSA) is developed to simultaneously suppress halide interstitial and vacancy defects by tuning the crystallization process of perovskite quantum dots (Pe‐QDs) through coordinate bonding and chemical circumstance modulation, leading to faster radiative recombination and less carrier accumulation in the device. Meanwhile, the Pe‐QDs with defect suppression demonstrate higher ion migration activation energies. Thanks to the defect suppression strategy with the aid of the alkyl sulfonic group, the obtained Pe‐QDs exhibit an external quantum efficiency (EQE) of up to 20.4% and an operating lifetime of over 100 h in QLED, which is the leading performance of green Pe‐QLEDs. This work provides a strategy from a different aspect for the perovskite QLED field in improving the performance and stability of devices. [ABSTRACT FROM AUTHOR]

The luminescence thermal quenching (LTQ) behavior is one of the detrimental effects which result in poor stability and hinder the practical applications of luminescent nanocrystals (NCs) severely. Suppressing the LTQ effect is fundamentally important, especially for the recent rising star lead halide perovskite NCs while related investigations are rare. Herein, taking CsPbBr3 NCs with high photoluminescence quantum yield (PLQY) as examples, a surface anchoring mechanism is proposed and the LTQ effect is successfully overcome. By introducing hybrid ligand system with large binding effect and steric hindrance, ligand desorption induces irreversible LTQ effect and the formation of surface atom vibration related transient traps is suppressed. As a result, 96.3% and 75.6% of the initial PL intensity are maintained up to 378 and 423 K, respectively, which are even superior to conventional core–shell NCs. Notably, after being treated under 333 K for 15 days, a PL intensity remnant of >88.4% is achieved. Such anti‐LTQ mechanism is also extended to blue perovskite NCs. Temperature‐tolerant stimulated emission and high temperature lasing phenomenon are fulfilled with considerable thermal stability. This work provides a new mechanism which can possibly help to solve the bottleneck toward practical luminescence applications for perovskite nanostructures. [ABSTRACT FROM AUTHOR]