Revealing excited states dynamics in cross-linked covalent hybrids of graphene and diketopyrrolopyrrole oligomers via ultrafast transient absorption spectroscopy

We report on ultrafast dynamics in cross-linked covalent hybrids of graphene and diketopyrrolopyrrole (TDPP) oligomers. Comparisons between non-polymerizing (EXG-TDPP) and polymerizing (c-EXG-TDPP) hybrids show that charge/energy transfer occurs faster than 50 ps in EXGTDPP, while the c-EXG-TDPP system shows quenching within 18 ps. The transient response of c-EXGTDPP is completely quenched (>99%), while in EXG-TDPP full quenching occurs after 1.39 ns. Photocurrent studies of c-EXG-TDPP films show IPCE > 2%, indicating ultrafast charge transfer between TDPP and graphene.