Rhodanine-3-acetic acid containing D-π-A push-pull chromophores: Effect of methoxy group on the performance of dye-sensitized solar cells

Three organic photosensitizers (TPA-R9, J-R9, CAR-R9) comprising of triphenylamine, julolidine and carbazole with methoxy group as an additional auxiliary donor and rhodanine-3-acetic acid as an acceptor were synthesized, and used in dye-sensitized solar cells application. The impact of the different donors with additional methoxy group on the photophysical, electrochemical, and photovoltaic properties are studied. The electron transfer kinetics are investigated by transient absorption spectroscopy and impedance spectroscopy. At a fixed V-OC, the electron lifetime increases in the order of donors: julolidine < diphenylamine < carbazole which are in accordance with the order of increasing V-OC. The transient absorption decays, in the presence of an electrolyte show half-times (tau(1/2)) of 1.40, 1.98, and 3.81 mu s of CAR-R9, TPA-R9, and J-R9 respectively. The short lifetime observed for the CAR-R9 proves the highest dye regeneration by I- allowing the highest short-circuit photocurrent density of 11.29 mA cm(-2). The efficiency of sensitizers obtained without addition of TBP ranged from 3.01 to 5.40%. The CAR-R9 shows superior photovoltaic performance with a short-circuit photocurrent density (Jsc) of 11.29 mA cm(-2), an open-circuit photovoltage (V-OC) of 0.656 V and a fill factor (FF) of 0.728, leading to power conversion efficiency (eta) of 5.40% under AM 1.5 irradiation (100 mW cm(-2)). An additional methoxy group significantly contributes to improving performance of the device.