Advances in single-crystal perovskite solar cells: From materials to performance

The power conversion efficiency (PCE) of polycrystalline perovskite solar cells (PSCs) has increased considerably, from 3.9% to 26.1%, highlighting their potential for industrial applications. Despite this, single-crystalline (SC) perovskites, known for their superior material and optoelectronic properties compared to their polycrystalline counterparts, often exhibit relatively lower PCEs. SC perovskites are characterized by a low concentration of grain boundaries, which contributes to lower defect densities, extended carrier lifetimes, and increased carrier diffusion lengths, potentially enhancing performance in optoelectronic devices. Moreover, SCs are ideal for investigating the fundamental optoelectronic properties of newly designed materials. This review examines the critical material properties of perovskite SCs relevant to developing efficient PSCs. It includes a discussion on the impact of defects and surface passivation, material composition, and strain on device performance. We also highlight advanced techniques for growing perovskite materials and provide an overview of recent progress in fabricating high-efficiency SC PSCs. Furthermore, we discuss the persistent challenges in thin-film SC growth and its potential to achieve higher PCEs than those observed in high-performance polycrystalline PSCs.