Suppression of Lattice Heterogeneity for Efficient Inverted Perovskite Solar Cells

ABSTRACT

Inverted perovskite solar cells (PSCs) exhibit operational stability and scalable manufacture, yet their performance is constrained by structural disorder and electrical flaws in the absorber layer. Heterogeneous crystal growth manifested as microstrain, unwanted phase impurities, and vertical composition gradients remains a limitation for both efficiency and stability. In this work, we used a rigid novel bifunctional molecule, 4,4‑dipyridyl sulfone (DPS), which effectively constrains the perovskite framework and drives the formation of a homogeneous and coherent lattice structure. The molecule removes vertical lattice misalignment, giving the film a consistent lattice spacing. Meanwhile, it increases the defect formation energy of lead and iodide vacancies, thereby suppressing defect generation and stabilizing the lattice. In addition, DPS facilitates compositional uniformity through dual‐site interaction, resulting in a uniform spatial distribution of FA ⁺ , Pb ²⁺ , and I ⁻ species throughout the absorber. The resulting inverted devices achieve a champion power conversion efficiency of 26.1% and, retain around 90.14% of their initial efficiency of continuous maximum power point tracking (MPPT) under 1‐sun illumination compared to the reference after 500 h. This work identifies lattice heterogeneity as a key barrier and demonstrates that its suppression provides a practical route toward efficient and stable perovskite photovoltaics.