Difunctional Polymerizable Additive Enables Efficient and Stable Wide‐Bandgap Perovskites for Perovskite/Organic Tandems Solar Cells

Abstract In perovskite‐organic tandem solar cells, the wide‐bandgap perovskite front subcells with high bromide concentrations suffer from increased defect state density, which adversely affects the efficiency and stability of the tandem devices. In this work, a difunctional polymerizable additive, N‐(3‐(dimethylamino)propyl)‐methacrylamide (DPM), is introduced into a 1.86 eV wide‐bandgap perovskite film, where it undergoes in situ thermal polymerization to form a polymeric network. Primarily, this polymer contains multiple functional groups that interact with A‐site cations of perovskite and adjacent polymer chains, creating a dynamic hydrogen bond network. This network effectively passivates grain boundary defects, inhibits ion migration, and consequently reduces non‐radiative recombination. In addition, the storage stability of the mixed FA + /MA + perovskite precursor solution is enhanced, as the condensation reaction between MA and FA + is efficiently suppressed by DPM. As a result, the study achieves a power conversion efficiency (PCE) of 18.19% in 1.86 eV wide‐bandgap perovskite solar cells. The device retains 84% of its initial efficiency after operating at its maximum power point for 1000 h. Most notably, a PCE of 25.06% is achieved by integrating the perovskite device as a wide‐bandgap subcell into the monolithic perovskite‐organic tandem solar cell.