Abstract

By doping bis-styrylbenzene derivative (BSB) into a wide energy gap 4,4′-bis(9-carbazole)-2,2′-biphenyl (CBP) host, we demonstrate an extremely low ASE threshold of E_th~0.1 μJ/cm² (220 W/cm²) which is the lowest amplified spontaneous emission (ASE) threshold ever reported. Further, we demonstrate a narrow emission from a thick co-deposited organic thin film, 6wt%-4,4′-bis-[(N-carbazole)styryl]-biphenyl (BSB-Cz) doped into a CBP host, under continuous-wave (CW) excitation. Although we observed no clear threshold characteristics on the spectral narrowing, we confirmed that the emission centered at a wavelength of λ,ASE = 462 nm, corresponding to the 0-1 transition of BSB-Cz, have a transverse electric (TE) mode with a narrow full width at half maximum of λ,FWHM = 3.4 nm, indicating occurrence of ASE. No excited state absorptions of singlet and triplet excited states of BSB-Cz are confirmed around λ,ASE leading to large net gain for the light amplification.

© 2007 APS DLS