High efficiency green InP quantum dot light-emitting diodes by balancing electron and hole mobility

Abstract

The industrialization of quantum dot light-emitting diodes (QLEDs) requires the use of less hazardous cadmium-free quantum dots, among which ZnSe-based blue and InP-based green and red quantum dots have received considerable attention. In comparison, the development of InP-based green QLEDs is lagging behind. Here, we prepare green InP/ZnSe/ZnS quantum dots with a diameter of 8.6 nm. We then modify the InP quantum dot emitting layer by passivation with various alkyl diamines and zinc halides, which decreases electron mobility and enhances hole transport. This, together with optimizing the electron transport layer, leads to green 545 nm InP QLEDs with a maximum quantum efficiency (EQE) of 16.3% and a current efficiency 57.5 cd/A. EQE approaches the theoretical limit of InP quantum dots, with an emission quantum yield of 86%.