Optimizing Green Perovskite Light-Emitting Diodes Through a Solution-Processed Triple-Layer HTL Strategy

Improving hole injection/transport and achieving charge balance through a multilayer hole-transporting layer (HTL) structure is a key technology for enhancing the performance of perovskite light-emitting diodes (PeLEDs). However, the stacking of a multilayer HTL through a solution process is constrained by the issue of erosion. We propose the use of 1,2-dichloroethane (DCE) as an orthogonal solvent for PTAA HTL, and a triple-layer HTL of [PTAA/TFB/PVK] was successfully realized solely through a solution-process. With an increase in the number of HTLs, there was an observed rise in external quantum efficiency (EQE) and a simultaneous reduction in turn-on voltage (Von) of the PeLED devices, attributed to a gradual decrease in the hole-injection barrier. In addition to the HTL, the integration of a double-layer electron-transporting layer (ETL) of [TPBi/PO-T2T] further enhanced overall device performance, resulting in a maximum EQE over 12 % and a Von as low as 2.22 V. The source of this enhancement was also investigated through time-resolved photoluminescence analysis and single-carrier device characterizations.