Quasi-solid-state dye-sensitized indoor photovoltaics with efficiencies exceeding 25%

Abstract

In this study, highly efficient dye-sensitized indoor photovoltaics (DSiPVs) are fabricated using quasi-solid-state cobalt-complex electrolytes. PVDF-HFP and PMMA polymers are employed as gelling agents to prepare these gel-type electrolytes. Although such polymers cause slow diffusion of redox couples, the related quasi-solid-state DSiPV cell still outperforms the liquid-state one under artificial-light conditions, which is attributed to the suppressed charge recombination at the photoelectrode/electrolyte interface. By regulating the PVDF-HFP/PMMA ratio and the electrolyte composition, this charge recombination can further be inhibited, thereby creating higher open-circuit voltages. Furthermore, in order to increase short-circuit currents, a cosensitization system and a polymeric catalyst are introduced, which respectively can broaden the light-harvesting region and facilitate interfacial charge transfer at the counter electrode. Consequently, the resultant quasi-solid-state DSiPV cell not only exhibits long-term stability during a 2000 h test, but also achieves a power conversion efficiency (PCE) beyond 25% under 1000-lux fluorescent lighting. The above materials are further utilized to assemble bifacial DSiPVs; the PCE obtained under rear illumination can surpass 91% of the front-illuminated value. Large-area module devices are also demonstrated herein, expressing the ability of powering small electronics in a fluorescent-light environment. This quasi-solid-state DSiPV technology is promising for self-powered electronics in the internet of things.