Optical and Electroluminescent Studies of White-Light-Emitting Copolymers Based on Poly(9,9-dioctylfluorene) and Fluorenone Derivatives

A novel type of single white-light-emitting copolymers, PF-DTFO x, derived from poly(9,9-dioctylfluorene) (PF) in which 2,7-di-(2-thienyl)-9-fluorenone (DTFO) is introduced as an orangeemitting unit, is reported, and their application in white-light polymer light-emitting devices (PLEDs) is explored. Because of the very simple structure of DTFO, the synthetic routes to PFDTFO x are not complicated, and the raw materials are cheap; these are advantageous in reducing the fabrication cost of white-light PLEDs. In the fluorescence spectra, PF-DTFO x in solid powder shows dual peaks at around 460 and 560 nm. In white-light PLEDs, the color of the white-light emission is tunable; this can be achieved by changing the content of DTFO in PF-DTFO x. The light-emission color varies from bluewhite to pure white and orange-white when the composition of DTFO increases. All the PLEDs based on PF-DTFO x exhibit maximum luminance above 1800 cd m(-2) and a color rendering index above 80.