High-Efficiency and Stable Green InP-QLED Enabled by Lowering Electron Injection Barrier

The external quantum efficiencies (EQE) and luminances of red InP-based and blue ZnTeSe-based quantum dot light-emitting diodes (QLEDs) have exceeded 20% and 80 000 cd m −2 , respectively, and the T 50 @100 cd m −2 (time for the luminance decreasing by 50%) operational lifetime of red InP-based QLEDs also have exceeded 1 000 000 h, nearing industrial application standards. However, the low EQE, luminance, and inferior lifetime of green InP-based QLEDs restrict the application for their full-color Cd-free display and lighting applications. The large electron injection barrier and severe exciton quenching caused by defect states of ZnMgO (ZMO) nanoparticles (NPs) lead to lower electron concentration in the emitting layer, which results in reduced radiative recombination. Here, with the surface passivation of MgCl 2 , the exciton quenching sites are significantly suppressed, and the electron injection barrier is reduced owing to the conduction band minimum (CBM) levels upshift of ZMO. As a result, a high EQE of 21.43%, maximum luminance of 25 5985 cd m −2 , along with a long T 50 @1000 cd m −2 (over 4 600 h) and T 50 @100 cd m −2 (over 290 000 h) operational lifetime is achieved for green InP-based QLEDs. These values have all exceeded the previous best values of green InP-based QLEDs.