Charge Transport in Blue Quantum Dot Light‐Emitting Diodes

Abstract

AbstractAlthough quantum dot light‐emitting diodes (QLEDs) are extensively studied nowadays, their charge transport mechanism remains a subject of ongoing debate. Here, the hole transport in blue quantum dots (QDs) (CdZnSe/ZnSe/ZnS/CdZnS/ZnS based) is investigated by combining current‐voltage and transient electroluminescence measurements. The study demonstrates that the hole transport in QD thin films is characterized by a trap‐free space‐charge‐limited current with a zero‐field room temperature mobility of 4.4 × 10−11 m2 V−1 s−1. The zero‐field hole mobility is thermally activated with an activation energy of 0.30 eV. Applying the Extended Gaussian Disorder model provides a consistent description of the QD hole current as a function of voltage and temperature. The QD hole mobility is characterized by a hopping distance of 2.8 nm in a Gaussian broadened density of states with a width of 0.12 eV.