Advances in Upconversion Nanoparticle Synthesis Methods for Photovoltaic Solar Cell

Renewable energy sources like solar power mitigate the negative effects of fossil fuel consumption and meet the ongoing demand for sustainable, pollution-free energy. Photovoltaic (PV) devices generate electricity directly from sunlight and are central to solar energy harvesting. Unfortunately, traditional solar cells can only use high-energy photons in the visible range, wasting the low-energy photons in the infrared (IR) and near-infrared (NIR) spectrum. The search for renewable energy solutions has advanced PV technology significantly, thanks to efficient and ecological innovations. One area in this field involves upconversion nanoparticles (UCNPs), which have gained attention for converting low-energy photons into higher-energy photons, thereby enhancing efficiency. This review covers the principles of upconversion, the design and synthesis of UCNPs for PV systems, and the challenges and opportunities that lie ahead. By critically examining the literature, the authors highlight key parameters for UCNP synthesis and provide optimisation strategies to boost PV performance. Finally, the review offers insights into potential future directions and applications of UCNP-based solar energy technologies for sustainable energy.