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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]

In‐situ and real‐time modulation of the optical properties of semiconductor nanoemitters by a CMOS‐compatible strategy holds great promise for developing functional and integrated optoelectronic devices. Herein, the reversible and giant (>13 times) enhancement of the photoluminescence (PL) from inorganic halide perovskite nanoplatelets by electrical bias is demonstrated for the first time. Based on the comprehensive spectroscopic analysis, the improved PL performance is attributed to the dynamic surface healing effect by bias‐induced ion redistribution. The switching from PL quenching to PL enhancement from CsPbBr3 nanoplatelet is manifested at threshold temperature of ≈190 K. Moreover, the temperature dependent measurements unravel the activation energy of 142.8 ± 31.1 meV, corroborating that the drifted species of anion (Br−) or VBr dominates the trap healing process. Accordingly, a three‐stage defect passivation model of the vertical configuration is established. The synergistic effects of ion redistribution and charge injection caused by thermal equilibrium energy band bending on the optical properties of the perovskite is further investigated by contacting the perovskite with indium tin oxide electrode. These results provide novel insight into the photophysical properties of halide perovskites and are beneficial for display and lighting applications in future, especially on‐chip integrated photonics circuits and systems. [ABSTRACT FROM AUTHOR]