Enhancing Efficiency and Intrinsic Stability of Large‐Area Blade‐Coated Wide‐Bandgap Perovskite Solar Cells Through Strain Release

Abstract The realization of efficient large‐area perovskite solar cells stands as a pivotal milestone for propelling their future commercial viability. However, the upscaling fabrication of perovskite solar cells is hampered by efficiency losses, and the underlying growth mechanism remains enigmatic. Here, it is unveiled that a prevalent upscaling technology, namely blade‐coating, inherently triggers top‐down inhomogeneity strains, predominantly concentrated on the surface of wide‐bandgap perovskite films. Through strain mitigation strategies, the perovskite films exhibit reduced halide vacancies, leading to enhanced stability and improved optoelectronic characteristics. Consequently, the blade‐coated perovskite solar cells achieve minimal efficiency loss when transitioning from small‐area to large‐area devices, enabling the realization of 1 cm 2 ‐area 1.77 eV‐bandgap cells with a remarkable efficiency of 18.71%. Additionally, the strain‐relieved device exhibits an exceptional 109% retention of its initial efficiency even after 400 h of continuous operation, in stark contrast to the control device which experiences a decline to 91%. Furthermore, the resulting 4‐terminal all‐perovskite tandem solar cells crafted utilizing blade‐coated 1.77 eV‐bandgap subcells achieve a maximum efficiency of 27.64% (stabilized at 27.28%). This study not only sheds light on the intricacies of upscaling preparation techniques but also overcomes potential obstacles that can impede the trajectory toward achieving large‐scale perovskite solar cells.