title: Porphyrin-sensitized solar cells with cobalt (II/III)-based redox electrolyte exceed 12 percent efficiency.
abstract: The iodide/triiodide redox shuttle has limited the efficiencies accessible in dye-sensitized solar cells. Here, we report mesoscopic solar cells that incorporate a Co((II/III))tris(bipyridyl)-based redox electrolyte in conjunction with a custom synthesized donor-π-bridge-acceptor zinc porphyrin dye as sensitizer (designated YD2-o-C8). The specific molecular design of YD2-o-C8 greatly retards the rate of interfacial back electron transfer from the conduction band of the nanocrystalline titanium dioxide film to the oxidized cobalt mediator, which enables attainment of strikingly high photovoltages approaching 1 volt. Because the YD2-o-C8 porphyrin harvests sunlight across the visible spectrum, large photocurrents are generated. Cosensitization of YD2-o-C8 with another organic dye further enhances the performance of the device, leading to a measured power conversion efficiency of 12.3% under simulated air mass 1.5 global sunlight.
authors: Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, Lausanne-1015, Switzerland.
authors: Aswani
authors: A
authors: Yella
authors: Hsuan-Wei
authors: HW
authors: Lee
authors: Hoi Nok
authors: HN
authors: Tsao
authors: Chenyi
authors: C
authors: Yi
authors: Aravind Kumar
authors: AK
authors: Chandiran
authors: Md Khaja
authors: MK
authors: Nazeeruddin
authors: Eric Wei-Guang
authors: EW
authors: Diau
authors: Chen-Yu
authors: CY
authors: Yeh
authors: Shaik M
authors: SM
authors: Zakeeruddin
authors: Michael
authors: M
authors: Grätzel