Facet Orientation Modulation for High-Performance of Printable Mesoscopic Perovskite Solar Cells

Carbon-based printable mesoscopic perovskite solar cells (p-MPSCs) offer substantial advantages for industrial production due to their facile fabrication, low cost, and scalability. In p-MPSCs, however, perovskites undergo disordered crystallization with multiple facets within the complex scaffold of mesoporous TiO₂ (mp-TiO₂)/mesoporous ZrO₂ (mp-ZrO₂)/mesoporous carbon (mp-C), resulting in film strain accumulation and restricted performance enhancement. To tackle this issue, we propose a facet orientation modulation strategy by introducing potassium sulfamate (ASK) to release strain accumulation in perovskite films. ASK exhibits a strong adsorption capability on the (001) crystal facet through interactions with the octahedral lattice, thereby promoting the formation of the (001) facet and enabling the preferentially oriented growth of perovskite films along this plane. Moreover, ASK effectively reduces the perovskite crystallization rate, allowing sufficient lattice reorganization and thus relieving residual stress during crystal growth. Ultimately, p-MPSCs employing this facet orientation modulation strategy achieved a champion power conversion efficiency (PCE) of 20.10%. ASK-optimized p-MPSCs retained 93% of their initial PCE after 150 days of storage in ambient air at room temperature, exhibiting excellent long-term stability.