Acidochromic pyrimidine-based dyes for highly efficient dye-sensitized solar cells

Abstract

Dye-sensitized solar cells (DSCs), employing dyes adsorbed on the surface of mesoporous titanium dioxide (TiO₂) films to convert light into electricity, have attracted great attention as viable alternatives in photovoltaic technology. However, the short-circuit current density (J_SC) of the device remains modest, limiting the power conversion efficiency (PCE). Extending the spectral response of the dyes is expected to boost the J_SC and thus PCE for DSCs. Herein, we report two D–A–A-featured dyes, MOTS₂P-Pyc and MOTP-Pyc, which utilize N-(pyrimidin-5-yl)pyrimidin-2-amine as an acidochromic core. Upon acid treatment of the MOTS₂P-Pyc-sensitized TiO₂ film, the absorption spectrum is significantly red-shifted by 100 nm, leading to a remarkable increment of the J_SC from 10 to 18 mA cm⁻² in the DSCs, which is among the highest for the DSCs sensitized with a single dye. This research opens a new path for designing acidochromic dyes, aiming to expand the spectral response and thereby enhance the light-to-electricity conversion efficiency of DSCs.