Understanding the Origin of Degradation of InP‐Quantum Dot Light‐Emitting Diodes

Abstract

Abstract The origin of degradation of InP‐QLED (quantum dot LED) is reported by comparing the stability of Cd‐QDs and organic Bebq 2 :Ir(mphmq) 2 (tmd) emissive layers (EMLs). The degradation causes of InP‐QLED are checked by measuring the stability of hole and electron only devices (HOD and EOD) against hole/electron, exciton stress, and hole/electron‐exciton stress conditions. The results show that the InP‐QDs layer is more vulnerable to exciton and electron‐exciton stress compared to the Cd‐QDs and Bebq 2 :Ir(mphmq) 2 (tmd) due to the increase of surface defects in the InP‐QDs after exciton and electron‐exciton stress, which increases non‐radiative Auger recombination process. However, InP‐QDs are relatively less stable against electron and hole stress than the Cd‐QDs and Bebq 2 :Ir(mphmq) 2 (tmd). To reduce the electron‐exciton stress on the InP‐QDs, an inverted red QLED with InP‐QDs:DBTA EML is fabricated. The QLED with InP‐QDs: hole transport layer (DBTA) shows a low driving voltage of 5.7 V, high external quantum efficiency (EQE) of 10.2%, and longer lifetime ( T 50 :557 h at 1000 cd m −2 ) than the reference InP‐QDs device ( T 50 : 29 h at 1000 cd m −2 ).