ABX3 Perovskites for Tandem Solar Cells

Perovskite solar cells carry the banner for emerging photovoltaics since they have demonstrated power conversion efficiency values well above 20%, which were traditionally only accessible for fairly established technologies such as silicon. Indeed, ABX perovskite materials have revolutionized solar cells due to their ease of processing and outstanding electronic and optical properties, which make them ideal candidates for the development of multi-junction devices aiming to surpass limits associated to stand-alone technologies. In this review we discuss the latest regarding this matter. First, we introduce standard materials and processing techniques involved in the preparation of state-of-the-art perovskite solar cells. We then discuss the development of perovskite-based tandem devices in which ABX perovskite acts as the active material in the top subcell and Si, CIGS, polymer, or ABX act as bottom subcells. Finally, we provide the reader with a discussion on the different lines of research that this rapidly developing field may follow. Worldwide energy consumption is experiencing a drastic increase due to our current way of life. Solar energy is proposed to be the main clean source to replace the burning of fuels. The transformation of solar energy in electricity is made through compounds that absorb solar radiation and spatially support the separation of electrical charge. In recent years a new semiconducting material based on ABX perovskites has emerged on the photovoltaic scene, recasting the field of new-generation solar cells since these materials promise superior efficiency at low cost. The research in perovskites pushed their photoconversion efficiency near to the thermodynamic limit. Now this barrier can be overcome by tandem architectures whereby two or more solar cells are stacked together, making more effective use of the incident solar radiation. In this review, we cover the state of the art of perovskite-based tandem solar cells from the description of ABX optoelectronic properties to their integration into multi-junction systems. ABX perovskite semiconductors offer superior optoelectronic properties at low fabrication costs. Míguez et al. review recent progress on the development of multi-junction solar cells based on these materials, which nowadays are attracting the interest of the photovoltaic community. The authors evaluate the impact of components and architectures on the overall performance of different tandems reported. Particularly, the combination of perovskite materials with well-established technologies, such as Si, in multi-junction architectures promises cost-effective devices with solar-to-electric conversion efficiencies surpassing 30%.