Perovskite Grain-Boundary Manipulation Using Room-Temperature Dynamic Self-Healing Ligaments for Developing Highly Stable Flexible Perovskite Solar Cells with 23.8% Efficiency

Flexible perovskite solar cells (pero-SCs) are the best candidates to complement traditional silicon SCs in portable power applications. However, their mechanical, operational, and ambient stabilities are still unable to meet the practical demands because of the natural brittleness, residual tensile strain, and high defect density along the perovskite grain boundaries. To overcome these issues, a cross-linkable monomer TA-NI with dynamic covalent disulfide bonds, H-bonds, and ammonium is carefully developed. The cross-linking acts as ligaments attached on the perovskite grain boundaries. These ligaments consisting of elastomers and 1D perovskites can not only passivate the grain boundaries and enhance moisture resistance but also release the residual tensile strain and mechanical stress in 3D perovskite films. More importantly, the elastomer can repair bending-induced mechanical cracks in the perovskite film because of dynamic self-healing characteristics. The resultant flexible pero-SCs exhibit promising improvements in efficiency, and record values (23.84% and 21.66%) are obtained for 0.062 and 1.004 cm(2) devices; the flexible devices also show overall improved stabilities with T-90 >20 000 bending cycles, operational stability with T-90 >1248 h, and ambient stability (relative humidity = 30%) with T-90 >3000 h. This strategy paves a new way for the industrial-scale development of high-performance flexible pero-SCs.

Automated summary

Flexible perovskite solar cells (pero-SCs) have the potential to complement traditional silicon SCs in portable power applications. However, their stability issues hinder practical use. A new strategy using cross-linkable monomer TA-NI as ligaments on perovskite grain boundaries is developed to improve their stability and efficiency. The resulting flexible pero-SCs show promising improvements in efficiency and stability, paving the way for industrial-scale development.