Organic dyes incorporating N-functionalized pyrrole as conjugated bridge for dye-sensitized solar cells: Convenient synthesis, additional withdrawing group on the π-bridge and the suppressed aggregation

Abstract

Two new N-functionalized pyrrole-based organic dyes were designed and synthesized for dye-sensitized solar cells. In addition to the normal acceptor of cyanoacetic acid moieties, another electron-withdrawing group, pentafluorophenyl or cyanophenyl one, was linked to the nitrogen atom of the pyrrole ring, with the aim to both suppress the aggregation of the dyes on the TiO2 surface and expand the electronic absorption spectra. As a result, dye LI-6 with pentafluorophenyl group as the auxiliary acceptor showed remarkable power conversion efficiencies of up to 6.23%, under AM 1.5G simulated solar light (100 mW/cm2), while that of N719 was tested to be 7.83% at the same measuring conditions.