Enhanced efficiency of DSSC by lyophilized tin-doped molybdenum sulfide as counter electrode

• Sn doped MoS 2 as counter electrode for dye sensitized solar cell. • Lyophilization process enhanced the performance of the counter electrodes. • Better crystallinity, morphology and electrocatalytic properties due to lyophilization. • The chemical state of elements was confirmed from XPS analysis. • The maximum efficiency (η) for the DSSC obtained is 7.14% by using the lyophilized Sn doped MoS 2 counter electrodes. The influence of lyophilization on the electrochemical properties of hydrothermally synthesized tin (Sn) doped molybdenum sulfide (MoS 2 ) nanostructures are investigated thoroughly. The lyophilized tin doped MoS 2 used as counter electrode (CE) in dye-sensitized solar cells (DSSCs) showed high efficiency and better stability. Power conversion efficiency (PCE) of 7.14% is achieved using lyophilized 2.5% Sn-doped MoS 2 as CE in DSSCs, which is much higher than devices made of CE comprising oven air annealed samples (5.74%). The major enhancement of PCE is due to the large surface area of Sn-doped lyophilized MoS 2 nanostructures as well as the high electrocatalytic activity of MoS 2 towards reduction reaction, which are observed from BET, CV and EIS measurements. Sequential CV scanning further showed the high electrochemical stability of the Sn-doped MoS 2 nanostructures. This indicates the useful application of lyophilizer technique to produce various other metal sulfide nanostructures to increase the porosity and overall surface area of the materials for optimum device performance.