(142d) Enhancing Quantum Dot Light Emitting Devices: Sub-Bandgap Turn-on and Electrobrightening Via Advanced Charge Transport Layer Engineering

Over the past decade, QD-LEDs have experienced remarkable improvements in device efficiency, yet the mechanism behind barrierless hole injection at voltages below the bandgap remained elusive. Our research team has identified the Fermi level alignment, influenced by surface states, as the key factor enabling this phenomenon. This alignment, coupled with the macroscopic electrostatic potential gain from the restructured energy environment, facilitates hole injection into quantum dots. Contrary to previous assumptions, we demonstrate that the
energy level alignment significantly outweighs the local carrier injection barrier alteration
caused by the Coulombic force of a charge in quantum dots. Our findings elucidate the
mechanism of barrierless carrier injection in QD-LEDs and propose a broader design principle for efficient electroluminescent systems utilizing nanocrystal emitters. Additionally, I will discuss the electrobrightening effect observed in quantum dots using ZnMgO as an electron
transport layer instead of ZnO.