Enhanced photovoltaic efficiency of hierarchically structured Cu2MnSnS4-PVP counter electrodes for platinum-free dye-sensitized solar cells

Quaternary chalcogenide, Cu₂MnSnS₄ (CMTS) was synthesized by hydrothermal method as a non-precious counter electrode (CE) for dye sensitized solar cells (DSSCs). PVP in different concentration was used along with CMTS, to generate various nanostructures. This work focusses on investigating the role of PVP on electrocatalytic properties of the different CMTS nanostructures. The structural, morphological, and electrocatalytic properties was done. XRD measurement confirmed stannite structure of CMTS. FESEM analysis showed flower like morphology of CMTS with PVP. The PVP concentration tunned the morphology of the CMTS nanostructure. In addition to morphology, electrical and electrochemical properties were changed. Cyclic voltammetry analysis revealed that the catalytic properties enhanced due to increase the PVP concentration. For the 1 g of PVP with CMTS exhibited high cathodic current density 0.0022 mA/cm² compared to the Pt CE. With increase in PVP concentration the resistivity decreased, and the mobility increased. Highest carrier concentration was observed for highest PVP concentration in CMTS. Nyquist plot displayed a decrease in series resistance and charge transfer resistance. DSSCs were fabricated using the CMTS samples as CE. I-V characterization were learned out to determine the efficiency of the devices. Open circuit voltage V_oc of 1 g of PVP with CMTS 0.74 V and short circuit current J_sc of 7.06 mA. cm^-2 which is comparable to Pt CE V_oc of 0.74 V and J_sc of 7.65 mA. cm^-2. Power conversion efficiency PCE of 1 g of PVP with CMTS 3.33% higher than other CMTS CE. This indicates electrocatalytic activity of flower like 1 g of PVP with CMTS was better for I^-/I₃^- redox reaction. Hence it is a good counter electrode material comparable to Pt CE for DSSC.