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Surface Regulation of CsPbBr <sub/>3</sub> Quantum Dots for Standard Blue-Emission with Boosted PLQY
摘要： It is demonstrated that, via surface treatment of CsPbBr3 perovskite quantum dots (PeQDs) by introducing small amount of organic ammonium chlorides possessing short alkyl chain (C ≤ 4) in methyl acetate in the typical purification process, the emission can be tuned from green to blue region with boosted photoluminescence quantum yield (PLQY). The Cl? mainly works on the surface of PeQDs to fill bromide vacancy, which generates a passivated mixed-halide surface and avoids formation of defects deep within bandgap. Meanwhile, the replacement of initial long-chain ligands with short chain ammonium moiety benefits the film PLQY. Accordingly, a standard blue emission of 461 nm with a high film PLQY of 52% is accessed and the corresponding colloidal shows a PLQY of 80% at 456 nm. This method is also proved to be a versatile tool to boost the PLQY of PeQDs by using short chain ammonium halides bearing the same X with the initial CsPbX3. A near-unity colloidal PLQY of 97% and 98% is achieved for CsPbBr3 and CsPbI3 respectively. Quantum dots light-emitting diode (QLED) with treated CsPbBr3 affords a standard blue electroluminescence of 459 nm and a maximum external quantum efficiency of 0.3%.
关键词： perovskite quantum dots,vacancy passivation,surface regulation,standard blue emission
更新于2025-09-23 15:21:01
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Chlorine Vacancy Passivation in Mixed Halide Perovskite Quantum Dots by Organic Pseudohalides Enables Efficient Rec. 2020 Blue Light-Emitting Diodes
摘要： Blue-emitting perovskites are easily attainable by precisely tuning the halide ratio of mixed halide (Br/Cl) perovskites (MHPs). However, the adjustable halide ratio also hinders the passivation of Cl vacancies – the main source of trap states leading to inferior performance blue MHP light-emitting diodes (LEDs). Here, we report a strategy to passivate Cl vacancies in MHP quantum dots (QDs) using non-polar-solvent-soluble organic pseudohalide (n-dodecylammonium thiocyanate (DAT)), enabling blue MHP LEDs with greatly enhanced efficiency. Density-functional-theory calculations reveal that the thiocyanate (SCN-) groups fill in the Cl vacancies and remove electron traps within the bandgap. DAT-treated CsPb(BrxCl1-x)3 QDs exhibit near unity (~100%) photoluminescence quantum yields; and their blue (~470 nm) LEDs are spectrally stable with an external quantum efficiency (EQE) of 6.3% – a record for perovskite LEDs emitting in the 460-480 nm range relevant to Rec. 2020 display standards – and a half-lifetime of ~99 s.
关键词： light-emitting diodes,organic pseudohalides,blue emission,perovskite,chlorine vacancy passivation,quantum dots
更新于2025-09-19 17:13:59