Organic ligands that capped the surfaces of perovskite nanocrystals (PeNCs) strongly influence the optical and electrical properties of the obtained PeNC films, which are fundamental for efficient perovskite light-emitting diodes (PeLEDs). Here, we systematically investigate the ligand effect through introduction of a ligand with strong π conjugation, 1-(1-naphthyl)ethylamine bromide (NEABr), for the fabrication of FAPbBr₃ PeNCs. Compared to the widely applied ligand phenylethylamine bromide (PEABr), NEABr molecules containing naphthalene rings have more delocalized electrons and better conductivity, which is beneficial for charge injection and transportation between interfaces. By varying the ligand ratio, high quality three dimensional FAPbBr₃ PeNC films with photoluminescence quantum yields up to 80% are fabricated. Based on the optimized PeNC films, electroluminescent (EL) devices achieve a maximum external quantum efficiency of 8.6%, which is about three times higher than that of EL devices based on PEABr. Importantly, by understanding the ligand effect, we demonstrate that the enhanced device efficiency is attributed to the lower defect densities and decreased interfacial resistance in the NEABr derived EL devices. Our findings about the effect of ligand conjugation on device performance may benefit other perovskite based optoelectronic devices.

中文翻译：

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高效FAPbBr3基绿色发光二极管配体共轭的调制

覆盖钙钛矿纳米晶体（PeNCs）表面的有机配体会强烈影响所得PeNC膜的光学和电学性质，这对于有效的钙钛矿发光二极管（PeLED）至关重要。在这里，我们通过引入具有强π共轭作用的配体1-（1-萘基）乙胺溴化物（NEABr），系统地研究配体效应，以制备FAPbBr ₃ PeNCs。与广泛使用的配体苯乙胺溴化物（PEABr）相比，含有萘环的NEABr分子具有更多的离域电子和更好的电导率，这有利于电荷注入和界面之间的传输。通过改变配体比例，获得高质量的三维FAPbBr ₃制备了具有高达80％的光致发光量子产率的PeNC膜。基于优化的PeNC膜，电致发光（EL）器件可实现8.6％的最大外部量子效率，这是基于PEABr的EL器件的约三倍。重要的是，通过了解配体效应，我们证明了增强的器件效率归因于NEABr衍生的EL器件中较低的缺陷密度和降低的界面电阻。我们关于配体结合对器件性能的影响的发现可能有益于其他基于钙钛矿的光电器件。