Colloidal II–VI quantum dots (QDs) exhibit near‐unity photoluminescence (PL) quantum yield (QY) when they are dissolved in dilute solution. However, when they are assembled into thin film, the PL QY is decreased significantly due to the presence of nonradiative Förster resonance energy transfer (FRET) among the close‐packed QDs. In this work, the FRET is suppressed by developing a binary‐QD light emission layer (EML), where blue‐QDs are introduced as spacers to spatially separate the red‐QDs. Due to the separation of red‐QDs, the FRET among red‐QDs is effectively suppressed and thus the emission properties of red‐QDs are well preserved. As a result, the PL QY of red‐QD thin film is enhanced by 1.5 times. When the binary‐QD EML is integrated into devices, the resultant QD light‐emitting diodes (QLEDs) exhibit a high external quantum efficiency of 21.64%. The work offers a new, simple and effective approach to suppress the FRET and improve the QY of QD thin film, which may open up a new avenue for developing efficient QLEDs with near‐unity internal quantum efficiency.

中文翻译：

---

抑制密装量子点薄膜中的Förster共振能量转移：朝着具有超过21.6％的外部量子效率的高效量子点发光二极管的方向发展

当胶体II–VI量子点（QD）溶解在稀溶液中时，它们会表现出近统一的光致发光（PL）量子产率（QY）。但是，当它们组装成薄膜时，由于密排QD之间存在非辐射福斯特共振能量转移（FRET），因此PL QY大大降低。在这项工作中，通过开发二进制QD发光层（EML）来抑制FRET，其中将蓝色QD作为间隔物引入以在空间上分隔红色QD。由于红色QD的分离，有效抑制了红色QD之间的FRET，因此可以很好地保留红色QD的发射特性。结果，红色QD薄膜的PL QY增强了1.5倍。当将二进制QD EML集成到设备中时，最终的QD发光二极管（QLED）的外部量子效率高达21.64％。这项工作为抑制FRET和改善QD薄膜的QY提供了一种新的，简单而有效的方法，这可能为开发具有近统一内部量子效率的高效QLED开辟新途径。