Stabilizing efficient wide-bandgap perovskite in perovskite-organic tandem solar cells

Iodide and bromide integration facilitate bandgap tunability in wide-bandgap perovskites, yet high concentrations of bromide lead to halide phase segregation, adversely affecting the efficiency and stability of solar cell devices. In this work, 2-amino-4,5-imidazoledicarbonitrile (AIDCN), with highly polarized charge distribution and compact molecular configuration, is incorporated into a 1.86 eV wide-bandgap perovskite to effectively suppress photoinduced iodine escape and phase segregation. Hyperspectral photoluminescence microscopy reveals that AIDCN mitigates phase segregation under continuous laser exposure. Concurrent in situ grazing-incidence wide-angle X-ray scattering and X-ray fluorescence measurements further validate suppressed iodine escape, evidenced by a notable slowing down of lattice shrinkage and a well-maintained overall chemical composition of the perovskite under continuous illumination. Applying this approach, we achieve a power conversion efficiency (PCE) of 18.52% in 1.86 eV wide-bandgap perovskite solar cells. By integrating this perovskite subcell with the PM6:BTP-eC9 organic subcell, the tandem attains a maximum PCE of 25.13%, with a certified stabilized PCE of 23.40%.