MoSe2 nanoflowers as a counter electrode for quantum dots sensitized solar cells

Layered transition metal dichalcogenides hold tunable and promising photoelectrochemical properties. MoSe2 is a potential candidate of the transition metal dichalcogenide family, which attracted interests of various fields such as photocatalytic, electrocatalytic, energy storage, sensing and optoelectronic applications. MoSe2 demonstrates high surface activity and strong absorption contributing to its enhanced electrocatalysis properties. The conversion from bulk structure to 2D nanosheets of MoSe2 increases the bandgap from 1.1 eV (indirect) to 1.55 eV (direct) analogous to Si, leading to wide utilization in optoelectronics. Herein, we have developed flowers-like nanostructured molybdenum diselenide (MoSe2) via hydrothermal method and studied their efficiency as counter electrode (CE) in TiO2/CdS/ZnS-based quantum dot-sensitized solar cells (QDSSC). The electrical conductivity studies indicate that the MoSe2 CE has higher electrical conductivity as compare to the conventional CuS CE as observed in this study. Accordingly, the power conversion efficiency of the developed QDSSC with MoSe2 as a CE is found to be 2.08%, while it is only 1.09% when CuS is used as the CE. The obtained efficiency of MoSe2 is attributed to their enhanced crystallinity along with 2D structure, high surface area and conductivity properties.