<p>Dye-sensitized solar cells (DSSCs) are being extensively researched to develop cost-effective and high performance photovoltaic cells, with the counter electrode material playing a crucial role in determining their overall cost. Carbon-based materials, particularly activated carbon derived from waste, have gained significant attention as viable alternatives to platinum due to their excellent electrical conductivity, high catalytic activity, and affordability. Incorporating composite materials alongside activated carbon further enhances DSSCs performance due to their multifunctionality. In this study, a composite paste of activated carbon derived from bamboo sticks and graphene in a 1:1 ratio was prepared as the counter electrode and evaluated in a solid-state DSSCs. Another critical strategy for improving DSSCs efficiency is enhancing the conductivity and stability of polymer electrolytes. To achieve this, multi-walled carbon nanotubes were employed as secondary fillers, while montmorillonite acted as a primary filler in poly(ethylene oxide)-based polymer electrolyte films, leading to improved electrical conductivity. The inclusion of a small amount of multi-walled carbon nanotubes facilitated the formation of conductive layers, increasing A.C. conductivity from 5.6 × 10⁻⁴ S cm⁻¹ to 6.63 × 10⁻³ S cm⁻¹. The combination of carbonized bamboo sticks with graphene as a counter electrode and an efficient solid polymer electrolyte resulted in the highest recorded solar efficiency of approximately 4.0%, demonstrating the potential of these materials in advancing DSSCs technology.</p>