Co-sensitization of amphiphilic ruthenium (II) sensitizer with a metal free organic dye: Improved photovoltaic performance of dye sensitized solar cells

A co-sensitization approach has been evaluated for achieving enhanced performance in dye sensitized solar cells wherein an amphiphilic ruthenium (II) sensitizer (Ru) is co-sensitized with a simple donor-pi-conjugated-acceptor (D-pi-A) type metal free alkoxy substituted organic dye (Y3). When compared to the devices fabricated from individual sensitizers, the co-sensitized device (Ru + Y3) showed significantly enhanced J(sc) value. Upon optimization, the device made of Ru + Y3 system yielded J(sc) = 14.32 mA/cm(2), V-oc = 0.602 V, ff = 0.73 and power conversion efficiency (PCE) = 6.29%. This performance is superior to that of either of the individual DSSCs sensitized with Ru (PCE = 5.21%) and Y3 (PCE = 3.30%) under similar fabrication and evaluation conditions. The enhanced PCE has been attributed to the fact that the co-adsorbent effectively overcome the competitive light absorption by I-/I-3(-), avoid dye aggregation, and reduce the charge recombination. (C) 2012 Elsevier B. V. All rights reserved.