A double-acceptor as a superior organic dye design for p-type DSSCs: high photocurrents and the observed light soaking effectElectronic supplementary information (ESI) available: Detailed electrochemical and photochemical data. See DOI: 10.1039/c4cp04010d

Herein, we report three novel single donor double acceptor dyes, BH2, 4, and 6, for use in p-type dye sensitized solar cells (DSSCs). BH4 yields one of the highest photocurrents, 7.4 mA cm −2 , to date. The high performance is achieved via a shorter synthetic route and no exotic materials or cell-building techniques. We suggest a structural principle when building dyes whereby one adopts a double acceptor/single anchor when a triphenylamine moiety is incorporated into a dye for p-type DSSCs. This strategy increases the molar extinction coefficient while simultaneously reducing the number of synthetic steps. The molar extinction coefficients (99 980 M −1 cm −1 ) reported herein are among the highest reported. Finally, we report the first-ever-observed light soaking effect in p-type DSSCs. A double-acceptor architecture for organic dyes is explored through device fabrication, DFT, impedance spectroscopy, electrolyte screening, and adsorption studies yielding very high molar extinction coefficients (99 980 M −1 cm −1 ), high photocurrents (7.4 mA cm −2 ), and the light soaking effect.