Multi-color Poly(Fluorenylene Ethynylene)s with On-Chain Phosphorescent Iridium(III) Complexes Through Energy Transfer

Abstract: A series of multi-color emitting conjugated polymers, poly(fluorenylene ethynylene) (PFE) with on-chain phosphorescent iridium(III) complex (Ir(thq)₂dbm) is synthesized. PFE copolymers with various contents of Ir(III)-complex units in the main chain are characterized by ¹H NMR, ¹³C NMR, and gel permeation chromatography. The photophysical properties, including absorption, photoluminescence (PL), PL excitation spectra, PL quantum efficiency, and PL decay are investigated in detail. Similar to the phase transition from α phase to β phase of polyfluorene, two kinds of conformations are found for PFE in solutions. The α-like phase is dominant in dilute solution, while β-like phase is dominant in condensed solution. Blue, yellow, and red emissions are achieved from the copolymer film with the Ir(thq)₂dbm feed ratios of 0, 8, and 16 mol%, respectively. Effect of ethynyl link in copolymer is discussed. Difference of PL spectra found for this series of copolymers between solution and film is analyzed using the energy transfer from PFE host to Ir(III)-complex guest. Graphical Abstract: A multi-color emitting conjugated polymer, poly(fluorenylene ethynylene) (PFE) with on-chain phosphorescent iridium(III) complex (Ir(thq)₂dbm), is synthesized. The photophysical properties are investigated. Blue, yellow, and red emissions are achieved from the copolymer film with the Ir(thq)₂dbm feed ratios of 0, 8, and 16 mol%, respectively. Difference of PL spectra found for PFE copolymers between solution and film is analyzed using the energy transfer from PFE host to Ir(thq)₂dbm guest.[Figure not available: see fulltext.]