Hallie R. Echelman, Jay B. Patel, King’s College London, London, United Kingdom
Silicon-based photovoltaics have long dominated the solar energy market due to their technological maturity accredited to decades of dedicated research. However, as their single junction efficiency is intrinsically constrained by the Shockley–Queisser limit, metal-halide perovskites have emerged as a promising material to overcome this limitation. Metal-halide perovskites possess various remarkable optoelectronic properties, including a tunable bandgap through compositional substitutions, allowing for reduced thermalization losses and tailored absorption. By enabling absorption across defined regions of the solar spectrum, perovskites are especially well-suited for integration into multijunction architectures to greatly enhance device efficiency. However, the scalable fabrication of compositionally precise perovskite films across a range of bandgaps remains a core challenge for industry readiness. While most research has focused on solution-based synthesis techniques, thermal evaporation offers significant advantages such as nanometer-scale thickness control, high reproducibility, and compatibility with large-area deposition. Furthermore, thermal evaporation allows for greater control of interface design and enhanced device stability through precise manipulation of film composition and homogeneity. By leveraging the advantages of vapor deposition, this work demonstrates the development of a fully evaporated 2.0eV wide-bandgap inorganic perovskite semiconductor as a top absorber in triple-junction devices. Through the pursuit of entirely evaporated high-efficiency devices, this research emphasizes the importance of thermal evaporation as an innovative technique for next-generation photovoltaic technologies.