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

ABSTRACT 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 Pb 2+ . 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/C 60 interface. This strategy facilitates the in‐situ reconstruction of the perovskite film, yielding a homogeneous microstructure that minimizes the contact resistance at the perovskite/C 60 interface. Furthermore, the synergistic effect of SPE and PDI markedly suppressed energy level mismatch‐induced and defect‐induced nonradiative recombination losses at the perovskite/C 60 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.