New organic dyes based on a dibenzofulvene bridge for highly efficient dye-sensitized solar cells

Three novel organic dyes, coded TK1, TK2 and TK3, incorporating two donor moieties, cyanoacrylic acid as an acceptor/anchoring group, the dibenzofulvene core and an oligothiophene spacer in a 2D–π–A system, were designed, synthesized, and successfully utilized in dye-sensitized solar cells. The dye TK3, containing two thiophene rings as spacers, shows an IPCE action spectrum with a high plateau from 390 nm to 600 nm, increased open-circuit photovoltage by 40 mV and short-circuit photocurrent by 7.03 mA cm−1, with respect to TK1. Using CDCA as the co-adsorbent material, the Jsc of TK3 was increased to 14.98 mA cm−1 and a strong enhancement in the overall conversion efficiency (7.45%) was realized by TK3 compared to TK1 (1.08%), in liquid electrolyte-based DSSCs.