Emergent P-N interfacial synergy in CoWO4-SnO2 nanohybrids unlocks efficient triiodide redox kinetics in dye-sensitized solar cells

In this work, we have successfully developed a CoWO 4 -SnO 2 nanohybrid using an eco-friendly hydrothermal synthesis method to construct dye-sensitized solar cells (DSSCs). The phase morphology, functional groups, and optical properties of the synthesized compounds using various characterization analytical tools. The self-assembled SnO 2 nanorods strongly connected with the CoWO 4 nanoparticles and confirmed by FE-SEM and HR-TEM results. The synthesized materials were employed as counter electrodes for DSSCs, and their performance metrics short-circuit current density (J sc ), open-circuit voltage (V oc ), fill factor (FF) and power conversion efficiency (PCE) were measured at 10.59 mA cm -2 , 0.725 V, 0.723 and 5.55%, respectively. The DSSC stability results showed that the PCE remained at 77% after 100 h, confirming the good stability of the fabricated DSSCs. The CoWO 4 -SnO 2 heterostructure exhibited superior electrocatalytic activity toward the reduction of the triiodide/iodide (I 3 - /I - ) redox couple. This improvement can be attributed to the synergistic interaction between CoWO 4 and SnO 2 . Mott-Schottky (M-S) analysis confirmed that P-type CoWO 4 and N-type SnO 2 form a P-N heterojunction at their interface, which facilitates interfacial charge transfer, reduces charge-transfer resistance, and thereby enhances the photovoltaic performance of the fabricated DSSCs.