Boosting Efficiency of InP Quantum Dots-Based Light-Emitting Diodes by an In-Doped ZnO Electron Transport Layer

InP quantum dots (QDs)-based light-emitting diodes (QLEDs) are considered as one of the most promising candidates for environmentally cadmium (Cd)-free electroluminescence devices. However, the performance of InP QLEDs still lags far behind that of Cd-containing QLEDs, which limits their practical applications in next-generation displays and lighting. Here, we report an all-solution processed green InP QLED, which is enabled by an electron transport layer (ETL) of In-doped ZnO (IZO) nanoparticles (NPs). The ETL of IZO NPs can not only suppress the exciton quenching of InP QDs emitting layer due to the reduced defect states, but also improve the charge balance by partially blocking the injection of electrons, and thus the device performance. The optimized InP QLED exhibits a maximum external quantum efficiency (EQE) of 5.42% corresponding to a current efficiency (CE) of 21.22 cd A(-1), which is three times higher than that of the control device based on ZnO ETL, respectively. Our work suggests that IZO NPs can function as a good ETL material in QLEDs and other optoelectronic devices.