100% fluorescence efficiency of 4,4′-bis[(N-carbazole)styryl]biphenyl in a solid film and the very low amplified spontaneous emission threshold

We examined the amplified spontaneous emission (ASE) characteristics of fluorescent styrylbenzene 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 Eth=0.32±0.05μJ∕cm2. We observed that the 6 wt %-BSB-Cz:CBP film has an ultimate photoluminescence (PL) quantum efficiency of ϕPL=100% and a short transient lifetime of τf=1.0±0.1ns, leading to a large radiative decay rate of kr=1×109s−1. We demonstrated that the extremely low ASE threshold originated from the large radiative decay rate of BSB-Cz.

[1]  N. Williams.  Collaboration Across Continents , 1996, Science.

[2]  C. Adachi,et al.  Ultraviolet amplified spontaneous emission from thin films of 4,4′-bis(9-carbazolyl)-2,2′-biphenyl and the derivatives , 2004 .

[3]  S. Forrest,et al.  Nearly 100% internal phosphorescence efficiency in an organic light emitting device , 2001 .

[4]  Chihaya Adachi,et al.  Simple Accurate System for Measuring Absolute Photoluminescence Quantum Efficiency in Organic Solid-State Thin Films , 2004 .

[5]  Alan J. Heeger,et al.  Low threshold distributed feedback lasers fabricated from blends of conjugated polymers: Reduced losses through Förster transfer , 2002 .

[6]  Stephen R. Forrest,et al.  Study of lasing action based on Förster energy transfer in optically pumped organic semiconductor thin films , 1998 .

[7]  OkumuraYasuaki,et al.  Low Threshold Gain-Narrowing Characteristics of Fluorescent Styrylbenzene Derivatives as a Guest Molecule in an Organic Thin-Film Optical Waveguide , 2000 .

[8]  S. Mashiko,et al.  Supernarrowing mirrorless laser emission in dendrimer-doped polymer waveguides , 2000 .

[9]  Tadashi Kusumoto,et al.  Highly efficient blue electroluminescence from a distyrylarylene emitting layer with a new dopant , 1995 .

[10]  A. Dodabalapur,et al.  Light amplification in organic thin films using cascade energy transfer , 1997, Nature.

[11]  Stephen R. Forrest,et al.  Prospects for electrically pumped organic lasers , 2002 .

[12]  Alan J. Heeger,et al.  Laser emission from solutions and films containing semiconducting polymer and titanium dioxide nanocrystals , 1996 .

[13]  Hidetoshi Yamamoto,et al.  Amplified spontaneous emission under optical pumping from an organic semiconductor laser structure equipped with transparent carrier injection electrodes , 2004 .

[14]  S. Forrest,et al.  Laser action in organic semiconductor waveguide and double-heterostructure devices , 1997, Nature.

[15]  R. H. Friend,et al.  Lasing from conjugated-polymer microcavities , 1996, Nature.