Solar energy is a clean source of energy that can help fulfill the increasing global energy demand.

The growth of high-quality single-crystal (SC) perovskite films is a great strategy for the fabrication of defect-free perovskite solar cells (PSCs) with photovoltaic parameters close to the theoretical limit, which resulted in high efficiency and superior stability of the device. Plenty of growth methods for perovskite SCs are available to achieve a maximum power conversion efficiency (PCE) surpassing 21% for SC-based PSCs. However, there is still a lot of room to further push the efficiency by considering new crystal growth techniques, interface engineering, passivation approaches, and additive engineering. In this review, we summarize the recent progress in the growth of SC-based perovskite films for the fabrication of high-efficiency and stable PSCs. We describe the impact of SC growth of perovskite films and their quality on the device performance and stability, compared with the commonly used polycrystalline perovskite films. In the last section, the challenges and potential of SCs in PSCs are also covered for future development.

The effect of rubidium and guanidinium additives on the morphological, optoelectronic and photovoltaic properties of the state-of-the-art triple A-cation based PSCs is investigated.

We have studied the effect of guanidinium incorporation in a single-crystalline MAPbI₃ perovskite on ion migration using temperature-dependent electrochemical impedance spectroscopy.