Photoexcitations in polycarbazolyldiacetylenes in different time regimes

Abstract We present the results of photoinduced absorption (PA) studies carried out on oligomers of 1(-N-carbazzolyl)penta-1,3-diyn-5-acetoxy (CPDA). From the temperature, laser intensity and chopper frequency dependence of the PA signals upon excitation at 488 nm, we have demonstrated that in the msec-sec range the dominant photocarries are charged bipolarons. The picosecond decay kinetics have been obtained on CPDA oligomer solutions by transient saturated absorption at 627 nm, measured by femtosecond pump and probe technique. The decay curves could be fitted to biexponential functions. These results are discussed in terms of the relaxation model proposed for other polydiacetylenes.