Novel zinc porphyrin sensitizers for dye-sensitized solar cells: Synthesis and spectral, electrochemical, and photovoltaic properties

摘要

Two donor-π-spacer-acceptor porphyrin dyes were synthesized for use in dye-sensitized solar cells. The dyes comprised the same donor (porphyrin derivative) consisting of 3,4,5-trimethoxybenzaldehyde and acceptor/anchoring group (carboxyl group) but varying π-spacer consisting of a Schiff base structure. Each of the dyes displayed different adsorption behavior and coverage on the TiO_2 surface. The porphyrin dyes P_(Zn)BIACOOH studied in this work exhibit red-shifted and broadened electronic spectra respect to the reference P_(Zn)COOH as expected. By the introduction of Schiff base unit at the meso positions, the energy level of E_(ox) (excited-state oxidation potentials) is significantly shifted to the positive compared with the reference P_(Zn)COOH, indicating a decreased HOMO-LUMO gap. The highest power conversion efficiency of the two dyes based on DSSCs reached 1.75% under AM 1.5 G irradiation.