Direct Contact of Selective Charge Extraction Layers Enables High-Efficiency Molecular Photovoltaics

Abstract

Summary Dye-sensitized solar cells (DSCs) are molecular photovoltaics that operate efficiently in direct solar and ambient light by employing dye-impregnated mesoscopic TiO 2 films with a redox electrolyte or hole conductor. Here, we report on an advanced DSC architecture, which achieves efficiencies of 13.1% under air mass 1.5 global, 100 mW cm −2 solar radiation, and power conversion efficiency of 32% under a standard Osram 930 Warm White fluorescent tube light at 1,000 lux intensity. The cell substantially benefits from the direct contact of the dye-impregnated TiO 2 film with the poly(3,4-ethylenedioxythiophene) (PEDOT) counter electrode acting as a hole collector. This reduces the diffusion path of redox mediator to merely the mesoporous TiO 2 film attenuating the Warburg resistance, which thereby boosts the photovoltaic performance. This architecture will not only accelerate the practical exploitation of DSCs, but also foster new types of light-harvesting devices using mesoscopic TiO 2 and PEDOT as electron and hole collection layers, respectively.