Interface parallel dipole regulation in all-perovskite tandem solar cells

Abstract

Constructing all-perovskite tandem solar cells (TSCs) provides an effective route to surpass the efficiency limit of single-junction perovskite solar cells (PSCs). A critical challenge lies in mitigating non-radiative recombination losses in wide-bandgap (WBG) PSCs, which significantly degrade their performance compared to theoretical predictions. Here, we propose a parallel dipole engineering strategy employing tailored phenoxyethylammonium halides (POEAX, X = I, Br, and Cl) to simultaneously heal defects and modulate interfacial electric fields. The POEA⁺ cations form an oriented dipole moment at the perovskite/C₆₀ interface, effectively binding with uncoordinated Pb²⁺ defects and enhancing the charge carrier transport. Meanwhile, the halogen anion Cl⁻, with its higher electronegativity, synergistically amplifies the dipole-bridged passivation and optimizes the energy level alignment, leading to highly improved film homogeneity and suppressed recombination. These advantages lead to a power conversion efficiency (PCE) of 19.54% and a remarkable open-circuit voltage (V_OC) of 1.352 V in 1.77 eV WBG PSCs. By integrating the optimized WBG subcell with low-bandgap PSCs, we demonstrated all-perovskite TSCs with a champion PCE of 28.92% (certified 28.51%) and excellent stability retaining 90% of the initial PCE after 1000 h under continuous operation.