Dynamic covalent bond-mediated suppression of phase segregation in wide-bandgap perovskites

Phase segregation triggered by illumination is a typical stimulus response in wide-bandgap perovskites, and addressing it is vital for overcoming the stability bottleneck of perovskite devices by mitigating phase segregation and implementing dynamic management. To tackle this, a dynamic covalent bond-mediated approach is proposed to deal with phase segregation in wide-bandgap perovskites. Results show that adding dynamic disulfide and diselenide bonds effectively suppresses phase segregation while keeping halogen homogeneity. A 1.77 eV wide-bandgap perovskite device attains a peak conversion efficiency of 21.02% and retains over 90% of its initial efficiency after 1200 h of continuous illumination at the maximum power point. A fabricated perovskite/perovskite tandem device reaches an optimal conversion efficiency of 28.45%. Incorporating dynamic covalent bonds presents a new strategy for mitigating phase segregation in wide-bandgap perovskites and is expected to drive further progress in this area.