双层膦氧化物分子修饰制备高效的大面积纯蓝光钙钛矿量子点发光二极管

Bilayer phosphine oxide modification toward efficient and large-area pure-blue perovskite quantum dot light-emitting diodes

蓝光卤素钙钛矿发光二极管(LED)由于其高色纯度和全色钙钛矿LED发展需求目前受到越来越多的关注.通过钝化卤素钙钛矿中的缺陷来提高LED性能是主要研究方向,然而,用于有效钝化混合卤素蓝光钙钛矿并获得性能优异、光谱稳定的纯蓝光LED方法还很有限.本文开发了一种使用含有膦氧基团的双层有机分子对混合卤素蓝光钙钛矿量子点进行固相修饰,不仅有效提高了量子点薄膜的发光性能,而且有效改善了LED的电荷平衡,显著提高了器件性能,获得了最大外量子效率为4.87%的纯蓝光LED(469 nm).作者发现双层膦氧分子与量子点之间可以发生强相互作用,从而有效钝化量子点,并有助于获得大面积单层钙钛矿量子点薄膜.其中,发光面积为64 mm2,波长为469 nm的LED最大外量子效率为3.91%.本文所述策略有助于推动性能优异的大面积钙钛矿量子点光电器件开发.

Blue emissive halide perovskite light-emitting diodes(LEDs)are gaining increasing attention.Reducing defects in halide perovskites to improve the performance of the resulting LEDs is a main research direction,but there are limited passivation methods for achieving efficient and spectrally-stable pure-blue LEDs based on mixed-halide perovskites.In this work,double modification layers containing phosphine oxides,i.e.,diphenyl[4-(triphenylsilyl)phenyl]phosphine oxide(TSPO1)and 2,7-bis(diphenylpho sphoryl)-9,90-spirobifluorene(SPPO13),are developed to passivate mixed-halide perovskite quantum dot(QD)films.The comprehensive spectroscopic and structural characterization results indicate the presence of strong interactions between TSPO1/SPPO13 and the QDs.Besides,the combination of the bilayer exhibits a synergistic hole-blocking effect,improving the charge balance of the LEDs.LEDs based on the QD/TSPO1/SPPO13 films deliver stable electroluminesence at 469 nm and present a maximum external quantum efficiency(EQE)and luminance of 4.87%and 560 cd m^(-2),respectively.Benefiting from the uniform QD/TSPO1/SPPO13 film over a large area,LEDs with an area of 64 mm^(2) show a maximum EQE of 3.91%,which represents the first efficient large-area mixed-halide perovskite LED with stable pure-blue emission.This work provides a method to improve the perovskite QDs-based film quality and optoelectronic properties,and is a step toward the fabrication of highly-efficient large-area blue perovskite LEDs.