Copoly(aryl ether)s with electron-transporting 2,7-bis(3-(trifluoromethyl) phenyl)-9,9-dihexylfluorene segments: Synthesis, optical, and electrochemical properties

We prepared and characterized three new copoly(aryl ether)s (P1-P3) consisting of alternate electron-transporting 2,7-bis(3(trifluoromethyl)phenyl)-9,9-dihexylfluorene and hole-transporting fluorophores (PI: 3,6-distyryl-N-2-ethylhexylcarbazole; P2: 2,7distyryl-9,9-dihexylfluorene; P3: 1,4-distyryl-2,5-dihexylbenzene) separated by ether spacers. The copolymers were soluble in common organic solvents such as chloroform, NMP, and 1,1,2,2-tetrachloroethane and exhibited good thermal stability with T(d)s higher than 360 degrees C. Optical properties of P1-P3 were investigated by comparing their absorption and photoluminescence spectra with those of compositional model compounds M1-M4. The emissions of P1-P3 are originated from both fluorophores (PI) or dominated by fluorophores with longer emissive wavelength via efficient energy transfer (P2 and P3). Cyclic voltammetric investigations confirm that incorporation of isolated hole-and electron-transporting segments leads to simultaneous enhancement of electron and hole affinity in these copoly(aryl ether)s. The HOMO and LUMO energy levels of P1-P3 are -5.15, - 5.28, - 5.17 and - 3.04, -3.06, -3.08 eV, respectively, and double-layer light emitting diodes of P1-P3 reveal emission maxima around 450-500 nm. (c) 2005 Elsevier Ltd. All rights reserved.