Solvent residue management: A key factor for achieving high efficiency and stability in printable mesoscopic perovskite solar cells

Carbon-based hole-transport-layer-free printable mesoscopic perovskite solar cells (p-MPSCs) have emerged as promising candidates for commercialization, owing to their cost-effective fabrication and scalable production. However, their fabrication faces a fundamental challenge: achieving complete perovskite infiltration and crystallization within the thick (∼3 μm) mesoscopic oxide scaffold while ensuring thorough solvent removal. Although recent advances in crystallization control, such as the development of in-plane directional crystallization using specialized covers with low-temperature annealing, have improved perovskite filling uniformity, the constrained solvent evaporation under low-temperature processing (60–80 °C) remains a critical bottleneck. The residual solvent significantly impairs charge carrier transport, thereby limiting device performance, while also compromising long-term operational stability, especially after device encapsulation and during thermal cycling between low and high temperatures. In this work, we systematically discuss how device architecture influences solvent retention, analyzes the impact of residual solvent on both device performance and stability, and evaluates various strategies for solvent removal. Furthermore, we propose several potential mitigation approaches to address the solvent removal challenge in p-MPSCs. These findings provide valuable guidelines for enhancing both the efficiency and long-term stability of p-MPSCs.