NH2-rich silica nanoparticle as a universal additive in electrolytes for high-efficiency quasi-solid-state dye-sensitized solar cells and quantum dot sensitized solar cells

Abstract

In this paper, a novel kind of functional NH2-rich silica nanoparticle (A-SiO2) as an electrolyte additive is reported, which is employed to assemble high-efficiency quasi-solid-state dye-sensitized solar cells (DSCs) and quantum dot sensitized solar cells (QDSCs), while the additional solidifying character of A-SiO2 makes it superior to the common additives. It is found that the A-SiO2 nanoparticle as an additive for ionic-liquid electrolyte can significantly improve the photovoltaic performance of quasi-solid-state DSCs, especially the open-circuit photovoltage (Voc) and fill factor (FF) through (1) negatively shifting the TiO2 conduction band (CB) edge, (2) effectively facilitating the ions transport and (3) remarkably inhibiting the charge recombination. Notably, DSC fabricated using the A-SiO2 based ionic-liquid gel electrolytes achieves a power conversion efficiency (PCE) of 7.30% under 1 sun illumination (AM 1.5 G, 100 mW cm−2), which is higher than that of DSC with the ionic-liquid electrolyte employing N-methylbenzimidazole (NMBI) and Guanidinium thiocyanate (GuNCS) as additives (PCE = 6.23%). Moreover, the A-SiO2 additive is of the universality in organic electrolytes for DSCs and polysulfide electrolytes for QDSCs. The PCE of CdS/CdSe co-sensitized QDSCs using A-SiO2 additives is improved by 34.9% due to the enhancement of short-circuit current density (Jsc) and Voc, resulting in a champion PCE of 7.11%, which is one of the best results for CdS/CdSe co-sensitized QDSCs.