A Review of the Synthesis and Properties of Graphene-TiO₂ Nanocomposites for Perovskite Solar Cells

The development of perovskite solar cells (PSCs) using sustainable green nanomaterials has indeed shown great promise in the renewable energy sector due to its high efficiency, low manufacturing cost, and potential for commercial viability. However, there are some issues that need to be addressed to make PSCs commercially available for the development of sustainable technology. These issues include stability, toxicity, scalability, and reliability. In this context, titanium dioxide (TiO₂) have been widely investigated as an electron transport layer (ETL) in PSCs due to its promising properties, including its high electron mobility and excellent stability. However, despite these advantages, TiO₂ also has some limitations, such as poor charge transport properties, a high rate of electron-hole recombinations, and poor visible light response due to its wide bandgap of ~3.2eV, which lowers the current and voltage densities of the solar cell. Researchers have explored ways of optimizing the morphology of TiO₂ with graphene nanomaterials, which can help in enhancing the performance and stability of PSCs because of their exceptional electrical conductivity, high electron mobility, large surface area, and excellent mechanical properties. This review summarizes the ongoing research in the field of the synthesis of graphene-based TiO₂ nanomaterials, reported by different authors across the globe as an ETL for PSCs. Existing issues and challenges associated with its synthesis is also highlighted in this paper. We have also reviewed the structural, morphological, optical, and photovoltaic properties of graphene-based TiO₂ nanomaterials.