Enhanced light out-coupling efficiency and reduced efficiency roll-off in phosphorescent OLEDs with a spontaneously distributed embossed structure formed by a spin-coating method. Issue 69 (12th September 2017)

• Record Type: Journal Article
• Authors: Yuan, Shuqing; Hao, Yuying; Miao, Yanqin; Sun, Qinjun; Li, Zhanfeng; Cui, Yanxia; Wang, Hua; Xu, Bingshe
• Is Part Of: RSC advances. Volume 7:Issue 69(2017)
• Page Start: 43987
• Page End: 43993
• Publication Date: 2017-09-12
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c7ra06921a
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : A randomly distributed scattering structure formed by a low cost simple solution based method to enhance efficiency and reduce efficiency roll-off. Abstract : A simple and low-cost spin-coating method was proposed to form a spontaneously distributed embossed structure. With such an embossed structure produced by Al2 O3 nanospheres (NPs) with different diameters, the out-coupling efficiency is increased in all viewing directions without introducing significant spectral changes and the efficiency roll-off is suppressed at the same time. When the concentration of Al2 O3 ethanol solution is chosen as 0.08 mg ml −1, a peak current efficiency (CE) of 52.1 cd A −1, peak power efficiency (PE) of 32.7 l m W −1, and peak external quantum efficiency (EQE) of 20.9% are obtained. From the maximum efficiency value to the case where the brightness is 3000 cd m −2, the roll-off of CE, PE and EQE for device B are only 6.53%, 26.30% and 6.22%, respectively. The improved properties are attributed to greatly enhanced light extraction and an enlarged charge carrier recombination region.