Improved efficiency of organic light-emitting devices employing bathocuproine doped in the electron-transporting layer

Abstract

We fabricate an organic light-emitting device (OLED) with improved efficiency by doping bathocuproine (BCP) into tris-(8-hydroxyquinoline) aluminium (Alq) as an electron-transporting and hole-blocking layer. The BCP dopant does not emit light itself, but adjusts the charge balance in the OLEDs by obstructing the passage of the redundant holes to the cathode and confining the exciton in the emitting zone, therefore resulting in the increased efficiency of the OLEDs. The cell with 5% BCP doping concentration has the highest luminous efficiency of 4.3 cd A−1 at 9 V, which is more than twice that of the undoped cell, and the highest power efficiency of 1.7 lm W−1 at 8 V, which is nearly twice that of the undoped cell. This is an effective method to improve the luminous efficiency of OLEDs.