High spectral response heteroleptic ruthenium (II) complexes as sensitizers for dye sensitized solar cells

Heteroleptic ruthenium(II) bipyridyl complex, cis-Ru(II)(4,4’-bis(4-tert-butylstyryl)-2,2’-bipyridyl) (4,4’-dicarboxy-2,2’-bipyridyl) (NCS2) (H112) was synthesized and characterized by 1H-NMR, MASS, Spectrofluorometer and UV-Vis spectroscopes. The photo-voltaic performance of the sensitizer was evaluated in Dye Sensitized Solar Cell (DSSC) under irradiation of AM 1·5G solar light and the photovoltaic characteristics were compared with those of reference cells of HRS1 and N719 fabricated under comparable conditions. Compared to N719, H112 sensitizer showed enhanced molar extinction coefficient and relatively better monochromatic incident photon-to-current conversion efficiency (IPCE) across the spectral range of 400 to 800nm with solar energy-to-electrical conversion efficiency (η) of 2·43% [open circuit photovoltage (V OC)=0·631V, short-circuit photocurrent density (J SC)=8·96mA/cm2, fill factor (ff)=0·430], while η values of 2·51% (V OC=0·651V, J SC=9·41 mA/cm2, ff=0·410) and 2·74% (V OC=0·705V, J SC=8·62mA/cm2, ff=0·455) were obtained for HRS1 and N719 sensitized solar cells respectively. The introduction of 4,4’-bis(4-tert-butylstyryl) moieties on one of the bipyridine moieties of N719 complex shows higher light absorption abilities, IPCE and J SC.