Tri(N-carbazolyl)triphenylamine-based starburst organic dyes: effects of different acceptors on the optical, electrochemical and photovoltaic properties

Abstract

Two novel tri(N-carbazolyl)triphenylamine-based organic dyes were designed, synthesized and applied as photosensitizers for dye-sensitized solar cells. The superiority of the starburst structure of these dyes is suppressing the intermolecular interactions and guaranteeing a fast electron injection into the TiO₂ semiconductor. Cyanoacrylic acid and rhodanine-3-acetic acid were separately used as electron acceptors/anchoring groups to compose the photosensitizers. Different acceptors led to striking changes in the photophysical, electrochemical and photovoltaic properties. An overall power conversion efficiency of 6.53% with a short-circuit photocurrent density of 13.4 mA cm⁻², an open-circuit photovoltage of 735 mV and a fill factor of 0.66 was achieved by the dye with tri(N-carbazolyl)triphenylamine as the donor and cyanoacrylic acid as the acceptor under AM 1.5 illumination (100 mW cm⁻²).