Luminence Efficiency and Color Stabilization of Blue Organic Light-Emitting Devices Fabricated Utilizing a 4,7-diphenyl-1,10-phenanthroline Electron Transport Layer Containing an Ultra Thin Trap Layer

Abstract

The hole blocking barrier in organic light-emitting devices (OLEDs) fabricated utilizing a 4,7-diphenyl-1,10-phenanthroline (BPhen) electron transport layer (ETL) with an ultra thin trapping layer was affected by the 5,6,11,12-tetraphenylnaphthacene (rubrene) or the tris(8-hydroxyquinoline) (Alq₃) trapping layer, acting as a trapping layer in the ETL. While the rubrene layer in the ETL decreased the number of electrons and holes in the emitting layer (EML), resulting in a decrease in the current density and the luminence of the OLEDs, the Alq₃ layer in the BPhen ETL did not block effectively the holes transfer from the EML to the ETL, resulting in a decrease in the luminence efficiency. The electroluminescence spectra showed that the magnitude of the holes blocked by the ETL was not significantly affected by the thin rubrene layer embedded in the BPhen ETL.

Keywords:

• Color stabilization
• luminence efficiency
• optical properties
• organic light-emitting devices

Acknowledgments

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2010-0018877).