Affiliation:
1. Sustainable Chemical Science and Technology Taiwan International Graduate Program and Institute of Chemistry Academia Sinica Taipei 11529 Taiwan
2. Department of Applied Chemistry National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan
3. Department of Electrical Engineering Graduate Institute of Photonics and Optoelectronics National Taiwan University Taipei 10617 Taiwan
4. Center for Organic Photonics and Electronics Research (OPERA) and International Institute for Carbon Neutral Energy Research (WPI‐I2CNER) Kyushu University Fukuoka 819‐0395 Japan
5. Research Center for Applied Sciences Academia Sinica Taipei 11529 Taiwan
6. Department of Electrical Engineering Yuan Ze University Taoyuan 32003 Taiwan
Abstract
AbstractBased on the classic 1,1′:4′,1″‐terphenyl fluorophore, a novel near‐ultraviolet (NUV) fluorescent BB4Ph (4,4″′‐bis(2,3,4,5‐tetraphenylphen‐1‐yl)(1,1′:4′,1″‐terphenyl) is designed, synthesized, and characterized. BB4Ph exhibits a NUV fluorescence with a λmax of 373 and 380 nm in solution and as a thin film, respectively. The grazing incidence wide‐angle X‐ray scattering (GIWAXS) reveals BB4Ph having a high value of order parameter (SGIWAXS) of 0.59 for a molecular layer array normal to the substrate; the angle‐dependent photoluminescence (ADPL) measurement shows Θ (horizontal–dipole ratios) as high as 95% with the neat film. The non‐doped BB4Ph organic light‐emitting diodes (OLEDs) show external quantum efficiency (EQE) up to 5.24% with 1931 Commission Internationale de l’ Eclairage coordinates (CIEx,y) of (0.16, 0.04), a NUV electroluminescence. With 4P‐Cz (9,9′‐(1,1′:4′,1″:4″,1′″‐quaterphenyl‐4,4′″‐diyl)dicarbazole) as a dopant emitter, doped BB4Ph OLEDs show the highest EQE of 6.99% and a NUV 1931 CIEx,y (0.16, 0.04). The photoluminescence quantum yield is measured for the thin film of BB4Ph and 4P‐Cz:BB4Ph as 68% and 96%, respectively. Hence, the low limits of light outcoupling efficiency (ηout) of the two individual OLEDs are estimated as 31% and 29%, respectively.
Funder
Ministry of Science and Technology
National Taiwan University
Subject
Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials