[The charge transfer process of PAN-C60 copolymer films by time-resolved fluorescence spectra]

The charge transfer (CT) process in PAN-C60 copolymer films was studied by absorption and picosecond time-resolved photoluminescence (TRPL) spectra. The CT process can be confirmed from the appearing of new absorption bands and fluorescence quenching of pure PAN in the copolymer films. The TRPL result revealed that excitation state relaxation obeyed biexponential decay process, which were 160 ps and 1,500 ps for the fast and slow decay process, respectively. The fast decay process results from the interaction of chains in the polymer, and a slow decay process comes from the singlet excition recombination. In the copolymer, the singlet excition state lifetime of PAN becomes shorter due to CT process between PAN and C60, which lead to PL quenching of PAN. Additionally, C60 molecules also affect the interchain interaction of PAN by its spacial shape, which closely relates with the fast decay process.