Green Interfacial Engineering via Synergy of Sugar Orange Peel Extract and Piperazine Dihydroiodide for Achieving Highly‐Efficient and Thermally‐Stable Perovskite Solar Cells

Serious non-radiative recombination at the interface hinders the improvement of power conversion efficiency (PCE) and stability in perovskite solar cells (PSCs). Meanwhile, the development of a comprehensive strategy for nontoxic and low-cost additives to reduce surface defects in the perovskite absorber is a critical issue for the industrialization of PSCs. Herein, an organic compound extracted from Sugar orange peel (SPE), which simultaneously contains C═C bonds and methoxy groups, can act as a Lewis base to incorporate into perovskite for the passivation of undercoordinated Pb²⁺. To address the stability issue originating from iodide ion vacancies and organic cation vacancies, a synergistic passivation strategy by utilizing SPE and low-toxicity piperazine dihydroiodide (PDI) was applied for the passivation at the perovskite/C₆₀ interface. This strategy facilitates the in-situ reconstruction of the perovskite film, yielding a homogeneous microstructure that minimizes the contact resistance at the perovskite/C₆₀ interface. Furthermore, the synergistic effect of SPE and PDI markedly suppressed energy level mismatch-induced and defect-induced nonradiative recombination losses at the perovskite/C₆₀ interface. Ultimately, the SPE&PDI-treated PSC achieved a champion PCE of 25.4% and retained over 84% of its efficiency after being continuously annealed at 85°C for 1200 h.