Platinum-free dye-sensitized solar cells by flower-like mixed-phase CoxSy/NixSy/MoxSy composites

Abstract

Many materials have been explored as a counter electrode material to replace platinum electrode in dye-sensitized solar cells (DSSCs). In this work, Co_xS_y/Ni_xS_y/Mo_xS_y composites at two different compositions, namely, CNM10, CNM25 were synthesized via hydrothermal method. The XRD, FE-SEM, and EDX analysis of the samples confirmed the formation of CNM10 and CNM25 composites. The cyclic voltammetry (CV) study of CNM10 and CNM25 electrodes showed faster triiodide ion reduction at the electrode/electrolyte interface than the Pt electrode. The electrochemical impedance spectroscopy studies of CNM10 and CNM25 electrodes showed lower R_CT values for both CNM10 and CNM25 electrodes than that of a Pt electrode. Tafel polarization measurement showed a higher limiting current value of CNM25 followed by CNM10 and Pt electrodes. Based on these studies, DSSCs were fabricated using CNM10, CNM25, and Pt CE. CNM25 CE showed an enhanced power conversion efficiency (PCE) (7.8%) with V_OC of 824 mV, and J_SC of 15.7 mA cm⁻², whereas, Pt CE showed PCE of 6.5% with V_OC of 775 mV and J_SC of 13.2 mA cm⁻².