Two-Photon Fluorescence Properties and Ultrafast Responses of a Hyperbranched Diketo-Pyrrolo-Pyrrole Polymer with Triphenylamine as the Core**Supported by the National Natural Science Foundation of China under Grant Nos 11404048, 61205154 and 11375034, the Fundamental Research Funds for the Central Universities under Grant Nos 3132015233, 3132013104, 3132014337, 3132015144 and 3132015152, the State Key Laboratory of Fine Chemicals (KF1409), and the Program for

Abstract

The two-photon fluorescence properties and ultrafast responses of a hyperbranched polyyne (hb-DPP-J2) with triphenylamine as the central core, Diketo-Pyrrolo-Pyrrole as the connecting unit and electron acceptor are studied. The polymer has a D-π-A-π-D conjugated structure along the extended polyyne π-bridge systems, and the effective conjugated unit repeats itself in the whole hyperbranched polymer chain. The polymer exhibits a large two-photon absorption cross section and high fluorescence quantum yields. The ultrafast dynamic results give a deep understanding of the excited energy transfer processes under excitation, and reveal a long relaxation lifetime of the intramolecular charge transfer (ICT) state.