Although much effort has been made to the cadmium-free quantum dot light emitting diodes (QLEDs), it is still a big challenge to achieve an efficient eco-friendly QLED. Here, an extremely efficient QLED based on Ag–In–Zn–S QDs is constructed with the insertion of an 1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene (TPBi) hole-spacing interlayer. The electrical properties of single carrier devices demonstrate the TPBi blocks the hole injection, leading to a more balanced charge injection in the device. Transient electroluminescence measurements confirm that the hole accumulation adjacent QDs is dramatically suppressed after the insertion of TPBi, hence limiting the interactions between excitons and holes. Consequently, the peak current (power) efficiency of 6.0 cd/A (6.5 lm/W) is achieved. To the best of our knowledge, this is the record efficiency for the Ag–In–Zn–S QLEDs reported to date. We anticipate this work will provide a new route for optimizing the performance of Cd-free QLEDs.

尽管已经对无镉量子点发光二极管（QLED）做出了很多努力，但是实现高效的环保QLED仍然是一个巨大的挑战。在这里，通过插入1,3,5-三（N-苯基苯并咪唑-2-基）苯（TPBi）的空穴间隔层，构造了基于Ag-In-Zn-S QDs的极其高效的QLED。单载流子器件的电性能证明TPBi阻止了空穴注入，从而使器件中的电荷注入更加平衡。瞬态电致发光测量结果证实，在插入TPBi之后，邻近QD的空穴积累得到了显着抑制，因此限制了激子与空穴之间的相互作用。因此，实现了6.0 cd / A（6.5 lm / W）的峰值电流（功率）效率。据我们所知，这是迄今为止报道的Ag-In-Zn-S QLED的记录效率。我们预计这项工作将为优化无镉QLED的性能提供一条新途径。