100% fluorescence efficiency of 4,4′-bis[(N-carbazole)styryl]biphenyl in a solid film and the very low amplified spontaneous emission threshold -: art. no. 071110

We examined the amplified spontaneous emission (ASE) characteristics of fluorescent styryl benzene derivatives doped into a 4,4'-di(N-carbazolyl)biphenyl (CBP) host. In particular, 4,4'-bis[(N-carbazole)styryl]biphenyl (BSB-Cz) demonstrated an extremely low ASE threshold of E-th = 0.32 +/- 0.05 muJ/cm(2). We observed that the 6 wt %-BSB-Cz:CBP film has an ultimate photoluminescence (PL) quantum efficiency of Phi(PL) = 100% and a short transient lifetime of tau(f) = 1.0 +/- 0.1 ns, leading to a large radiative decay rate of k(r) = 1 x 10(9) s(-1). We demonstrated that the extremely low ASE threshold originated from the large radiative decay rate of BSB-Cz. (C) 2005 American Institute of Physics.