High efficiency bifacial quasi-solid-state dye-sensitized solar cell based on CoSe2 nanorod counter electrode

Abstract

For traditional dye-sensitized solar cells, one method to increase the long-term stability and enhance the power conversion efficiency (PCE) is to explore the use of bifacial and quasi-solid-state cells (BQDSSCs). In the current work, CoSe2 nanorods with lengths of 70–500 nm and widths of 20–60 nm were prepared via a simple hydrothermal method and served as the counter electrode (CE) material. The photovoltaic results of the bifacial cell revealed that the front and rear irradiation PCEs of the CoSe2 CE can reach 8.02% and 4.22%, which are higher than those of Pt CE (7.46% and 4.04%, respectively), by employing a polyvinylidene fluoride quasi-solid-state electrolyte. Moreover, the CoSe2 nanorod CE possess a good light on-off photocurrent response and switching stability in the BQDSSCs device. The excellent efficiency and long-term photovoltaic stability of the CoSe2 CE-based BQDSSCs were derived from the unique one-dimensional nanostructure and superior electrocatalytic properties for the reduction reaction of I3− to I−, as revealed by cyclic voltammetry (CV), Tafel polarization, and electrochemical impedance spectroscopy (EIS) measurements. Furthermore, the CoSe2 CE material exhibits excellent electrochemical stability for catalyzing the reduction of I3−. Our work inspires the development of high efficiency selenides electrode materials for use in the BQDSSCs field.