Co-sensitization of “H”-type dyes with planar squaraine dyes for efficient dye-sensitized solar cells

Abstract

Three “H”-type dyes with different linkage mode of two “D–π–A” moieties (LI-101, LI-102 and LI-103) were synthesized and applied to the co-sensitized system with the famous metal-free NIR squaraine dye of SQ2. Thanks to the advantage of the “H” configuration and their complementary spectra, the co-sensitized system exhibited the much improved photovoltaic performance of about a 70% enhancement, in comparison with that of SQ2 itself. Among them, the LI-102/SQ2 co-sensitized solar cell exhibited the highest conversion efficiency of 7.44% with 16.6 mA cm⁻² for J_sc, 714 mV for V_oc, 0.63 for FF.