One-Dimensional Rod-Structured Cryptomelane α-MnO ₂ /2H-MoSe ₂ /Polypyrrole Hybrid as an Efficient Counter Electrode for Natural DSSCs

Developing an efficient material as a counter electrode (CE) with excellent catalytic activity, intrinsic stability, and low cost is essential for the commercial application of dye-sensitized solar cells (DSSCs). Transition metal dichalcogenides have emerged as versatile catalytic materials with promising electrochemical properties for energy conversion systems. Here, we developed an α-MnO2-modified 2H-MoSe2/polypyrrole (MSPMN) ternary composite as a CE for DSSCs employing natural plant-derived dyes. A microwave-assisted synthesis method was used for the controlled incorporation of α-MnO2 into MoSe2/polypyrrole at varying ratios (3:1, 3:2, and 3:3), producing well-defined structural, chemical, and morphological characteristics confirmed by XRD, FTIR, Raman spectroscopy, FESEM, EDAX, and TGA/DTA analyses. Natural sensitizers extracted from Leucas aspera (L), Tibouchina urvilleana (T), and their cocktail blend (LT) were obtained using a microwave-assisted method and characterized using UV–vis absorption, FTIR, and FESEM to elucidate optical behavior and adsorption characteristics. DSSCs assembled with MSPMN-based CEs exhibited composition-dependent catalytic behavior, where the electrode with MSPMN2 composition (3:2 ratio) yielded the most favorable photovoltaic performance. Co-sensitization with the LT cocktail enhanced device performance through improved light harvesting and synergistic electron injection, resulting in a power conversion efficiency of 1.62% for the MSPMN2/LT device.