Co-sensitization of N719 with an Organic Dye for Dye-sensitized Solar Cells Application

Abstract

The co-sensitization of N719 with a cyclic thiourea functionalized organic dye, coded AZ5, for dye-sensitized solar cells (DSSCs) was demonstrated. Due to its intensive absorption in ultraviolet region, AZ5 could compensate the loss of light harvest induced by triiodide, thereby the short-circuit photocurrent density (<TEX>$J_{sc}$</TEX>) was increased for co-sensitized (N719+AZ5) DSSC. Moreover, the electron recombination and dye aggregation were retarded upon N719 cocktail co-sensitized with AZ5, thus the open-circuit voltage (<TEX>$V_{oc}$</TEX>) of co-sensitized device was enhanced as well. The increased <TEX>$J_{sc}$</TEX> (17.9 <TEX>$mA{\cdot}cm^{-2}$</TEX>) combined with the enhanced <TEX>$V_{oc}$</TEX> (698 mV) ultimately resulted in an improved power conversion efficiency (PCE) of 7.91% for co-sensitized DSSC, which was raised by 8.6% in comparison with that of N719 (PCE = 7.28%) sensitized alone. In addition, co-sensitized DSSC exhibited a better stability than that of N719 sensitized device probably due to the depression of dye desorption.