Emerging applications of metal-organic frameworks and derivatives in solar cells: Recent advances and challenges

The utilization of naturally existed energy is an indispensable solution to realise carbon neutral society in the future. Solar energy in the Sun is a tremendously abundant renewable and green energy resource which can provide more than enough energy to meet the whole world's demand. The biggest challenge is to develop cost-effective and durable materials to achieve efficient transformation of solar energy to electricity. As the most promising energy harvesting devices that based on the photovoltaic effect, solar cells can effectively transfer sunlight into electricity and the technologies have expanded rapidly over recent decades. Materials with optimal properties are the key to achieving efficient solar energy-driven performance for a variety of solar cells. Metal-organic frameworks (MOFs) and their derivatives, featured a great symbiosis of morphological, physicochemical and semiconducting properties that are difficult to achieve through the conventional materials, were intensively explored for energy storage and conversion applications in the past decade due to their intrinsic porous structures, tremendous inorganic-organic nature and fantastic diversity in functionalities. MOFs and derivatives based photovoltaic devices, especially solar cells, have demonstrated exceptional potential to enhance solar-to-electricity conversion performance with increased stability. In this review, the state-of-the-art progress on the applications of MOFs and their derivatives in a diverse range of solar cell devices including dye-sensitized solar cells, perovskite solar cells and organic solar cells is systematically documented. Important aspects on material compositions and structures, material synthesis strategies, device processing techniques, and photovoltaic performances of MOFs-based and MOF-derived materials used in solar cells are discussed and analyzed. The utilizations of MOFs and their derivatives as electrodes, photoactive materials, charge carriers and additives in different solar cells are highlighted. In addition, current challenges and perspectives on further development of MOF based materials for solar cell applications are also discussed.