Dye Sensitized Solar cells

The global demand for clean and renewable energy sources has led to extensive research and development in photovoltaic technologies, with solar cells emerging as a key solution to the energy crisis. Solar energy is an abundant, sustainable, and environmentally friendly alternative to fossil fuels, which contribute to greenhouse gas emissions and climate change. Third-generation solar technologies, such as Dye-Sensitized Solar Cells (DSSCs), quantum dot solar cells (QDSC), perovskite solar cells, and hybrid solar cells offer a cost-effective and flexible alternative, making solar energy more accessible. DSSCs leverage photoelectrochemical principles, providing an efficient way to harvest sunlight even under low-light conditions, thus expanding their applicability in diverse environments. To enhance the efficiency and stability of DSSCs, significant research is focused on optimizing two critical components: the counter electrode (CE) and the photoanode.

Photoanode

The photoanode is responsible for light absorption and electron transport in DSSCs. Titanium dioxide (TiO₂) is the most commonly used material due to its high surface area and favorable band structure. However, research is ongoing to improve charge separation and transport by exploring for that we have synthesized Ag nanoparticles on TiO₂/rGO nanostructures as a photoanode in DSSC with superior photovoltaic performance with a maximal Jsc of 16.05 mA/cm2 which leads to an enhanced efficiency of 7.27 % (Nanomaterials., 2022, 13, 65). In order to tailor the band edge potential BaSnO₃ photoanode by including the Y³⁺ showed the optimum band edge potential of (-0551 eV) facilitates the charge transfer from the dye molecule (J. Phys. Chem. Solids., 2023, 179, 111367). The ZnO nano spindle decorated over TiO₂ mesosphere to explore the photon-induced charge carrier migration/transfer kinetics in the photoanode system. Regarding the power conversion efficiency, the TiO₂/ZnO exhibits improved photovoltaic characteristics at different temperatures (CrystEngComm, 2023, 21, 3198-3209).

Fig 1. Device fabrication using co-doped materials and their charge transfer band diagram (Schematic)

Moreover, the influence of co-dopant Y³⁺/La³⁺ in Ba site of BaSnO₃ has improved the overall efficiency where TiO₂ has been utilized as a compact layer effectively alter the band alignment of valence and conduction band (Opt. Mat.,2024, 156, 115952).

Counter Electrode in DSSCs

The counter electrode (CE) is a crucial component of Dye-Sensitized Solar Cells (DSSCs), playing a vital role in the regeneration of the redox electrolyte and the overall efficiency of the cell. Positioned opposite the photoanode, the counter electrode facilitates electron transfer to the electrolyte, enabling continuous power generation. Traditionally, platinum (Pt) is used as the counter electrode material due to its excellent catalytic activity and conductivity. However, to reduce costs and improve sustainability, alternative materials such as carbon-based electrodes, conductive polymers, and transition metal compounds are being explored. Optimizing the counter electrode is essential for enhancing DSSC performance, stability, and scalability for practical applications.

Addressing the challenges associated with conventional DSSC counter electrodes, such as high material costs, limited stability, and complex fabrication processes, is a key focus of our research. We aim to replace expensive and scarce platinum-based electrodes with cost-effective and stable alternatives, including inorganic materials like NiO, SnS₂, ZnCo₂O₄ and Co-based materials composited with carbon-based materials. To enhance large-scale production feasibility, we have adopted a hydrothermal growth method on conductive substrates, eliminating the need for complex coating techniques. This approach ensures improved catalytic activity, durability, and scalability for real-world DSSC applications. The initial phase of our research focuses on optimizing the coating the materials on conductive substrates, analyzing their structural and morphological properties, and improving electrochemical performance. Strategies such as doping, band engineering, and surface modifications are employed to enhance catalytic activity and electron transfer, ultimately boosting the overall efficiency and stability of DSSCs.

Fig 2. Band energy levels and intrinsic charge carrier transfer within the device (Schematic)

Our research focuses on optimizing material coatings on conductive substrates, enhancing structural properties, improving electrochemical performance, and boosting catalytic activity, achieving an efficiency of 7.10% (Int. J. Hydrogen Energy, 2024, 91, 380-392). We synthesized SnS₂ and rGO composites, which exhibited a power conversion efficiency (PCE) of 7.3%, surpassing Pt CE (6.5%) and pristine SnS₂ (4.7%), attributed to enhanced redox reaction kinetics (Opt. Mater., 2024, 157, 116243). Furthermore, nitrogen-enriched porous g-C₃N₄/rGO demonstrated superior electrochemical properties, achieving a PCE of 6.9% as a DSSC counter electrode (Electrochim. Acta, 2025, 512, 145370). Similarly, cobalt (Co)-substituted NiO nanosheets (NSs) were synthesized via a hydrothermal method and used as CEs for DSSCs. Structural and electrochemical analyses confirmed an enhanced surface area, improved charge transfer, and superior electrocatalytic activity, resulting in a PCE of 5.01% (Sol. Energy, 2025, 286, 113124).