Controllable and large-scale fabrication of rectangular CuS network films for indium tin oxide-and Pt-free flexible dye-sensitized solar cells

Here we present a highly flexible and large-area CuS transparent conductive film (TCF) fabricated by colloidal crackle pattern as a counter electrode (CE) for flexible dye sensitized solar cell (DSSC). This rectangular CuS TCF can be fabricated on arbitrary flexible substrates at low temperature and exhibits superior mechanical robustness in bending cycling measurement. The transmittance and conductivity can be accurately controlled by controlling the sizes and shapes of the crackle patterns, similar to 90% transmittance can be achieved when the sheet resistances (R-s) are similar to 60 Omega sq(-1). Moreover, such CuS TCF has strong receivable ability of pH (1-13) and temperature changes (0-100 degrees C). In the application of DSSC as CE, the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses of the CuS networks exhibit a comparable electrocatalytic behavior with the platinum (Pt) networks on polyethylene terephthalate (PET), yielding a power conversion efficiency (PCE) of 4.54% for DSSC based on CuS networks as CE and retaining > 90% PCE after 500 bending cycles. Such CuS TCF with high transparency, flexibility, conductivity and electrochemical catalytic ability shows great potentials in other wearable, light-weight electrochemical cells.