Dynamics of energy transfer of a dioxolane-substituted pentacene dispersed in 4,4-bis[N-1-naphthyl-N-phenylamino]biphenyl

We examine the steady-state and time-resolved photoluminescence of guest-host films featuring a dioxolane-substituted pentacene derivative (2,2,10,10-tetraethyl-6,14-bis(triisopropylsilylethynyl)-1,3,9,11-tetraoxadicyclopentab,m]pentacene, EtTP-5) dispersed in the hole transporting material (4,4-bisN-1-naphthyl-N-phenylamino]biphenyl, alpha-NPD). The films show bright red emission (lambda(max) = 640 nm) as a result of efficient F?rster energy transfer from alpha-NPD host molecules to EtTP-5 guest molecules. High absolute photoluminescence (PL) quantum yield (phi(PL) = 76% +/- 4%) and fluorescence lifetime (tau = 18.6 +/- 0.8 ns) were measured at low concentration (0.28 mol % EtTP-5), with moderate PL quenching observed upon increasing the EtTP-5 concentration. The concentrated films (> or = 1.50 mol % EtTP-5) show less evidence of aggregation than previously seen when EtTP-5 was dispersed in tris(quinolin-8-olato)aluminum(III), making alpha-NPD a superior host for the red-emitting EtTP-5.