强化载流子传输实现高亮度高效率钙钛矿量子点发光二极管

Strengthening Carrier Transmission to Achieve High Brightness and High Efficiency of Perovskite Quantum Dot Light Emitting Diodes

金属卤化物钙钛矿量子点因其具有高光致发光量子产率、高色纯度、带隙可调等优良的光学性能,具备成为下一代发光显示材料的潜力。目前,红绿钙钛矿量子点发光二极管(PQLED)的电致发光效率已经达到有机发光二极管(OLED)的水平。然而,有机长链配体阻碍了电荷的传输,导致钙钛矿量子点发光二极管在最大外量子效率(EQE)下的亮度较低。为了实现钙钛矿量子点发光二极管在最大EQE下仍然具有较高的发光亮度,我们用无机配体CaBr2部分替换有机长链配体,强化PQLED中的载流子传输,并提升电致发光的载流子注入。同有机长链配体和有机短链配体相比,无机配体能够减缓有机链存在所造成的电绝缘性,改善QDs电导性,进一步增强QDs的发光特性。基于这种策略,我们实现了在3753 cd/m^(2)高亮度下峰值EQE为10.57%的钙钛矿量子点发光二极管。在6.6 V的工作电压下,PQLED的最大亮度高达116612 cd/m^(2)。

Metal halide perovskite quantum dots have the potential to become the next generation of luminescent display material because of their excellent optical properties such as high photoluminescence quantum yield,high color purity and adjustable band gap.At present,the electroluminescence efficiency of red-green perovskite quan‐tum dot light-emitting diode(PQLED)has reached the level of organic light-emitting diodes(OLED).However,or‐ganic long-chain ligands hinder charge transport,resulting in a lower brightness of perovskite quantum dot light-emit‐ting diodes at maximum external quantum efficiency(EQE).In order to realize that the perovskite QDs still have high luminescence brightness at the maximum EQE,we replaced the organic long-chain ligand with the inorganic li‐gand CaBr2,strengthened the carrier transmission in PQLED,and enhanced the electroluminescent carrier injec‐tion.Compared with organic long-chain ligand and organic short-chain ligand,inorganic ligand can slow down the electrical insulation caused by the existence of organic chains,improve the conductance of QDs,and further enhance the luminescence characteristics of QDs.Based on this strategy,we achieved perovskite quantum dot light-emitting diodes with a peak EQE of 10.57%at a high brightness of 3753 cd/m^(2).At an operating voltage of 6.6 V,the maxi‐mum brightness of the PQLED is 116612 cd/m^(2).