Unsymmetrical squaraines incorporating quinoline for near infrared responsive dye-sensitized solar cells.

Two new unsymmetrical squaraines (WCH-SQ10 and WCH-SQ11), wherein the electron-rich 3,4-ethylenedioxy-thiophene conjugated fragment was linked unconventionally to the squaraine core and triphenyl amine donor, and carboxylic acid substituted quinoline was used as an acceptor, were prepared. WCH-SQ10 and WCH-SQ11 dyes in ethanol have the λ(max) of 686 and 673 nm, respectively. The corresponding photovoltaic devices exhibit an attractively panchromatic response over 1000 nm, suggesting that quinoline benefits the low energetic electron injection.