Improved Quantum Efficiency of Organic Light Emitting Diodes with Gradiently Doped Double Emitting Zone
GAO Wen-Bao1, JIANG Wen-Long2, SUN Jia-Xin1, FENG Jing1, HOU Jing-Ying1, LIU Shi-Yong1
1National Laboratory of Integrated Optoelectronics, Jilin University, Changchun 130023
2Electronic Information and Engineering Department, Jilin Normal University, Siping 136000
Improved Quantum Efficiency of Organic Light Emitting Diodes with Gradiently Doped Double Emitting Zone
1National Laboratory of Integrated Optoelectronics, Jilin University, Changchun 130023
2Electronic Information and Engineering Department, Jilin Normal University, Siping 136000
Abstract： We investigate electroluminescent characteristics of gradiently doped organic light-emitting diodes, which were gradiently doped in both the hole and the electron-transporting layer to form a double emitting zone. The device structure was ITO/(15 nm) CuPc/(60 nm)NPB:rubrene/(30 nm)Alq3:rubrene (20 nm)Alq3/(0.5 nm)LiF/Al. We observed that charge carriers were well trapped by the dopant molecules and the main emitting zone was localized at the NPB:rubrene side close to the interface of NPB:rubrene/Alq3:rubrene. The quantum efficiency (cd/A) was enhanced to 5.89 cd/A at 6 V. We attributed this improvement to the charge carriers trapping and the emitting of the double emitting zone.
2003, Vol. 20 
