Enhanced catalytic performance of Cu2ZnSnS4/MoS2 nanocomposites based counter electrode for Pt-free dye-sensitized solar cells

Abstract

Low abundance, high cost and corrosiveness towards the liquid electrolyte is the main limitation of Platinum (Pt) as a counter electrode (CE) in dye-sensitized solar cells (DSSCs) in spite of its excellent electrochemical properties. The present study focuses to enhance the electrochemical properties of CZTS by compositing it with MoS2 towards the replacement of Pt. Pure CZTS, pure MoS2, CZTS/MoS2 nanocomposites are synthesized by hydrothermal method, then characterized and compared to analyze their properties. The outcomes of characterizations techniques from XRD, Raman, XPS, SEM, EDS and TEM confirmed the formation of CZTS/MoS2 nanocomposites. The electrochemical characterizations and Impedance analysis of the pure CZTS, pure MoS2 and CZTS/MoS2 are compared. Results showed enhanced catalytic property and lower charge transfer resistance for the CZTS/MoS2 nanocomposites. Nanocomposite with 8 wt% of MoS2 in CZTS exhibited higher carrier concentration of 6.126 × 1018 cm−3, higher mobility of 5.03 cm2Vs−1 and lower resistivity of 2.62 Ωcm compared to CZTS and other nanocomposites. Electrical conductivity and catalytic activity were improved with increase in the wt% of MoS2 in the Cu2ZnSnS4/MoS2 nanocomposites. DSSC device fabricated by interpolating di-tetrabutylammonium cis-bis(isothiocyanate)bis(2,2″-bipyridyl-4,4′dicarboxylato) ruthenium (II) (N719) dye-loaded titanium dioxide (commercial P25 TiO2 as photoanode) and with CZMo8 (as CE) using iodine/iodide as a liquid electrolyte exhibited the maximum open circuit voltage of 720 mV, a short circuit current of 8.45 mA/cm2, a fill factor of 0.66, and a power conversion efficiency of 4.07%.