Ying-Hsiao ChenKuo-Chun TangJiun-Yi ShenYu-Sin WuShih-Hung LiuChun-Shu LeeChang-Hsuan ChenTzu-Yu LaiSHIH-HUANG TUNGRU-JONG JENGWen-Yi HungMin JiaoCHUNG-CHIH WUPI-TAI CHOUChen Y.-T2019-10-242019-10-24201620416520https://scholars.lib.ntu.edu.tw/handle/123456789/427860https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971283979&doi=10.1039%2fc5sc04902d&partnerID=40&md5=564d7911b0d6e7516cbac6c6e94db0e5Fundamental insight into excimer formation has been gained by using 9,10-bis[4-(9-carbazolyl)phenyl]anthracene] (Cz9PhAn) as a probe. Cz9PhAn exhibits a highly emissive blue fluorescence in solution and is found to emit a panchromatic white light spectrum (400-750 nm) in film, powder and single crystal, in which an additional excimer band appears at ∼550 nm. Detailed structural analyses, emission relaxation dynamics and a theoretical approach conclude the formation of an anthracene∗/phenyl ring excimer through an overlap between π∗ (anthracene) and π (phenyl ring) orbitals in a face-To-edge stacking orientation. The rate of excimer formation is determined to be 2.2 × 109 s-1 at room temperature, which requires coupling with lattice motion with an activation energy of 0.44 kcal mol-1. Exploiting Cz9PhAn as a single emitter, a fluorescent white organic light emitting diode (WOLED) is fabricated with a maximum external quantum efficiency (ηext) of 3.6% at 1000 cd m-2 (4.2 V) and Commission Internationale de L'Eclairage (CIE) coordinates of (0.30, 0.33). The white-light Cz9PhAn reveals a preferred orientation of the transition dipole moment in the emitting layer to enhance light outcoupling. This non-doped, single component (Cz9PhAn) WOLED greatly reduces the complexity of the fabrication process, rendering a green and cost-effective alternative among the contemporary display/lighting technologies. © The Royal Society of Chemistry 2016.Activation energy; Anthracene; Cost effectiveness; Fluorescence; Light emitting diodes; Organic light emitting diodes (OLED); Single crystals; Contemporary displays; External quantum efficiency; Preferred orientations; Stacking orientation; Theoretical approach; Transition dipole moments; White organic light emitting diodes; White-light generation; Optoelectronic devicesjournal article10.1039/c5sc04902d2-s2.0-84971283979