Efficient CsPbIBr₂ Perovskite Solar Cells: Precise Control of Film Growth through the Application of Organic Iodized Salt and Anti-solvent

Abstract

Full-inorganic CsPbIBr2 optoelectronic devices have received huge attention in energy technology owing to their prime photovoltaic properties and promising thermal stability. However, CsPbIBr2 perovskite films obtained by conventional spin coating always have bad morphology, poor crystallinity, and thin thickness, which subsequently reduced the device performance. In this work, an assistant solution, isopropanol solution containing different organic iodide salts (FAI), was successfully introduced during the spin coating process, where isopropanol solution acted as the effective anti-solvent and FAI was used as the surface passivator. A film with suitable thickness (500 nm) with a pure-phase perovskite film having an average grain size of 600 nm and high coverage and being pinhole-free could be created by further controlling and optimizing the CsPbIBr2 crystals. The high-quality CsPbIBr2 film resulted in greatly impeded charge recombination and increased charge transfer and extraction efficiency. Therefore, a power conversion efficiency (PCE) of about 9% was obtained, which is 110% enhanced compared to that of the pristine device. In addition, the proposed CsPbIBr2 perovskite solar cells showed excellent long-term stability by encapsulation, which could show a 10% initial PCE loss after storing in the ambient environment for 1000 h. This work indicates that the adopted strategy is an effective and huge potential technology to improve photovoltaic performance, which can be further applied in other inorganic photovoltaic fields.