Electrochemical and power conversion performance of different counter electrode materials for flexible dye-sensitized solar cells

Abstract

Carbon dots and copper indium sulfide are promising photovoltaic materials, which have so far been fabricated mainly by chemical deposition methods. In this work, carbon dots (CDs) and copper indium sulfide (CIS) were separately combined with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) for the preparation of stable dispersions. These prepared dispersions were used to produce CIS-PEDOT:PSS and CDs-PEDOT:PSS films using the ultrasonic spray deposition (USD) approach; furthermore, platinum (Pt) electrodes were fabricated and tested for flexible dye sensitized solar cells (FDSSCs). All the fabricated electrodes were utilized as counter electrodes for FDSSCs, and the power conversion efficiency of the FDSSCs reached 4.84% after 100 mW cm⁻² AM1.5 white light was used to excite the cells. More investigation reveals that the improvement might be caused by the CDs film's porosity network and its strong connection to the substrate. These factors increase the number of sites available for the effective catalysis of redox couples in the electrolyte and facilitate the movement of charge in the FDSSC. It was also emphasized that the CIS film in the FDSSC device helps to generate a photo-current. In the beginning, this work shows how the USD approach can create CIS-PEDOT:PSS and CDs-PEDOT:PSS films and confirms that a CD based counter electrode film produced using the USD method is an interesting replacement for the Pt CE in FDSSC devices, while the results obtained from CIS-PEDOT:PSS are also comparable with standard Pt CE in FDSSCs.