Efficient light emitting devices utilizing CdSe(ZnS) quantum dots in organic host matrices

Abstract

We demonstrate efficient electroluminescence from thin film structures containing core-shell CdSe(ZnS) quantum dots dispersed in molecular organic host materials. In the most efficient devices, excitons are created on the quantum dot sites via energy transfer from organic host molecules, and direct charge injection into the quantum dots is minimized. For quantum dots with core diameter 38 [Angstroms], the electroluminescence spectra peak at 562nm and have full width at half maximum as narrow as 32nm. Saturated color devices have external quantum efficiencies as high as 0.61% at the current density of 7mA/cm². At 125mA/cm², the device luminance is 1900cd/m², which corresponds to a luminescence efficiency of 1.5 cd/A. The yield over hundreds of devices is greater than 90%, indicating a robust material system.