Empowering perovskite modules for solar and indoor lighting applications by 1,8-diiodooctane/phenethylammonium iodide 2D perovskite passivation strategy

To accelerate commercialization of perovskite technology and its use in multiple application fields, several device processing strategies have been developed. These efforts primarily target scaling-up device fabrication for mass production and enhancing performance for different light sources (sun or indoor light). This work presents a novel 3D/2D perovskite heterostructure by depositing a mixed layer of phenethylammonium iodide (PEAI) and 1,8-diiodooctane (DIO) directly atop the 3D perovskite absorber without a further annealing step. The addition of DIO enables the formation of pure 2D PEA₂PbI₄ 4 (n = 1) at room temperature, leading to defect passivation of 3D perovskite surface, improvement in the crystallinity of 2D perovskite, and optimizing the dipole moment at perovskite/hole transport interface. Large-area PSC modules treated with PEAI:DIO achieve remarkable power conversion efficiencies of 17.7 % (32 cm²) and 15.6 % (121 cm²) under 1Sun irradiation. When exposed to indoor illumination with various LED intensities (200, 500 and 1000 lux) the PEAI:DIO engineered module demonstrated efficiency approaching 34 %, among the highest reported so far for large area modules employing perovskite with bandgap below 1.7 eV. Long-term stability tests following the ISOS-D-1 protocol reveal a threefold increase in T₈₀ lifetime compared to untreated devices.