Asymmetrical squaraines for high-performance small-molecule organic solar cells with a short circuit current of over 12 mA cm−2

Abstract

An asymmetrical squaraine dye (Py-3) with its two electron-donating aryl groups directly linked to the electron-withdrawing squaric acid core possesses an ideal bandgap of 1.33 eV, together with an intense and broad absorption band in the range 550–950 nm. Hence, the resulting solution-processed solar cells display an impressive J_sc of 12.03 mA cm⁻² and a PCE of 4.35%.