Graphene-Modified Photoelectrodes for Efficient Dye-Sensitized Solar Cells: A Review

Dye-sensitized solar cells (DSSCs) have emerged as a promising alternative to conventional photovoltaic technologies due to their cost-effectiveness, color transparency, flexibility, and environmental compatibility, particularly for building-integrated photovoltaic (BIPV) applications. Despite these advantages, the practical commercialization of DSSCs has been limited by their relatively low photoconversion efficiency (PCE) and stability issues. Central to the performance of DSSCs is the photoelectrode, which is typically composed of mesoporous TiO₂layers responsible for dye adsorption and electron transport. However, intrinsic limitations such as sluggish electron transport, high recombination rates, and insufficient light harvesting capability significantly hinder the overall device performance. Graphene’s exceptional electron mobility, high-surface area, and tunable electronic properties enhance electron transfer, minimize recombination losses, and improve light absorption and scattering. Although numerous reviews have broadly addressed graphene incorporation into DSSC components, a detailed analysis emphasizing the specific roles and performance implications of graphene within individual layers of the photoelectrode remains limited. This comprehensive review critically assesses the role of graphene-modified photoelectrodes across three distinct layers: the blocking layer, the transparent mesoporous layer, and the scattering layer. By systematically reviewing literature from the past 15 years, this work elucidates the impact of different graphene forms on each layer’s functionality and overall DSSC efficiency. The challenges associated with graphene defects and conductivity trade-offs, as well as practical considerations for optimizing graphene-based photoelectrodes, are also highlighted. This structured overview serves as a valuable guide for researchers aiming to further optimize graphene-based DSSCs and advance their commercial viability.