Ligand memory effect in purple quantum dot LEDs

Abstract

We report a ligand-dependent, trap state memory effect in a purple quantum dot light emitting diode. The measured, bistable current-voltage characteristics show a high conductance state and a low conductance state. Thereby, a memory window with an ON state and an OFF state is achieved, which can be reversed by applying a negative bias. The height of the memory window depends strongly on the length of the ligand passivating the quantum dot (QD). Together with a 5 nm thick aluminum film under the hole transport layer, charges accumulate at the charge transport/quantum dot ligand interface, leading to an increase in conductance during the forward voltage sweep. During a reverse voltage sweep, p..