This work demonstrates a strategy to improve the photovoltaic performance of a well-known chlorophyll derivative, chlorin e(6), with molecular engineering. By introducing alkyl ester substituents at the C15 and C17 positions of the chlorin macrocycle of chlorin e(6), the short-circuit photocurrent (J(sc)), the open-circuit photovoltage (V-oc), and the solar energy-to-electricity conversion efficiency (eta) of dye-sensitized solar cells were improved from 2.5 mA cm(-2), 0.47 V, and 0.9% to 6.6 mA cm(-2), 0.60 V, and 2.9%, respectively. The eta value was further improved to 6.7% with J(sc) = 15.6 mA cm(-2), V-oc = 0.65 V, and fill factor (FF) = 0.66 with relocation of the carboxy group and extension of the cyclic pi system on the C3-substituent. These improvements were attributed to the reduced charge recombination between the TiO2 semiconductor and redox couple in the electrolyte as well as the enhanced electron-injection and light-harvesting efficiencies. (C) 2013 Elsevier B.V. All rights reserved.