Four new pyrrole-based organic sensitizers with different isolation groups were conveniently synthesized and applied to dye sensitized solar cells (DSCs). The introduction of isolation group in the side chain could both suppress the formation of dye aggregates and electron recombination. Especially, when two pieces of D-π-A chromophore moieties shared one isolation group to construct the “H” type dye, the performance was further improved. Consequently, in the corresponding solar cell of LI-57, a short-circuit photocurrent density (Jsc) was tested to be 13.85 mA cm–2, while 0.72 V for the open-circuit photovoltage (Voc), 0.64 for the fill factor (FF), and 6.43% for the overall conversion efficiency (η), exceeding its analogue LI-55 (5.94%) with the same isolation group. The results demonstrated that both the size (bulk and shape) and the linkage mode between the D-π-A chromophores and the isolation groups, could affect the performance of sensitizers in DSCs in a large degree, providing a new approach to optimize the chemical structure of dyes to achieve high conversion efficiencies.Keywords: dye-sensitized solar cell; isolation group; organic sensitizer; pyrrole; “H” type dyes;

The synthesis, one- and two-photon absorption (2PA) and emission properties of two novel pyrrole-based conjugated polymers (P1 and P2) are reported. They emitted strong yellow-green and orange fluorescence with fluorescent quantum yields (Φ) of 46 and 33%, respectively. Their maximal 2PA cross sections (δ) measured by the two-photon-induced fluorescence method using femtosecond laser pulses in THF were 2392 and 1938 GM per repeating unit, respectively, indicating that the 2PA chromophores consisting of the triphenylamine with nonplanar structure as the donor and electron-rich pyrrole as the conjugated bridge could be the effective repeating units to enhance the δ values.