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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]

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]

Abstract: Halide perovskite microplatelets (HPeMs) with ultrahigh crystallinity and large lateral dimension provide a good potential for realizing new micrometer‐scale light sources. However, the difficulty of obtaining uniform microplatelet thin films imposes the impediment for getting light sources in the conventional vertical configuration. Here, bright electroluminescence (EL) from a light‐emitting device based on solution‐processed large HPeMs is obtained using alternating current (AC) voltage in a planar device configuration. The bright and stable EL driven by 50 Hz demonstrates that this AC‐driven light‐emitting device can directly couple with household power supplies, thereby simplifying the electrical circuit modulation. The low‐frequency‐driven capability can be originated from the high charge carrier mobility and long carrier lifetime in perovskites, i.e., the hole accumulation can be reduced near the metal electrode to allow more hole injection, and more long‐lifetime holes can wait for injected electrons to recombine. Moreover, the shift of peak position and full‐wavelength‐at‐half‐maximum in the temperature‐dependent EL spectra reveals that the electric‐induced ionized scattering centers and related ion migration might have been neglected in the widely studied temperature‐dependent photoluminescence measurements. This work demonstrates an alternative operating mechanism and light‐emitting device configuration for obtaining EL from perovskites, offering a new manner to get novel micrometer‐scale perovskite light sources. [ABSTRACT FROM AUTHOR]