Evaluation of amplified spontaneous emission from photopumped thiophene/phenylene co-oligomers in polycrystalline states

Abstract

We examined the thermal crystallization of deposited films made of 2,5-bis(4-biphenylyl)thiophene (BP1T) and 1,4-bis(5-phenylthiophen-2-yl)benzene (AC5), which are thiophene/phenylene co-oligomers (TPCOs). The deposited films of both BP1T and AC5 showed a microcrystalline phase, and initial microcrystals got larger 10 -100 times with thermal treatment. Furthermore, we measured the optical properties of microcrystals of BP1T and AC5. At the energy density below the spontaneous amplified emission threshold, it was found that there was a big fluorescent difference between femtosecond laser irradiation and continuous lamp irradiation.