Application of benz[c,d]indolenine-based unsymmetrical squaraine dyes to near-infrared dye-sensitized solar cells

Abstract Novel benz[ c,d ]indolenine-based unsymmetrical near-infrared squaraine dyes having germinal butyl ( η  = 0.55%) and octyl ( η  = 0.58%) groups at another indolenine ring exhibited higher conversion efficiency than the usually used methyl derivative ( η  = 0.38%). The germinal butyl and octyl groups can inhibit aggregation formation and approaching I 3 − species to improve the conversion efficiency.