Additive passivation strategies to improve properties of evaporation-spray coating perovskite solar cells†

Abstract

The evaporation-spray coating process has been applied in the field of perovskites. However, perovskite solar cells fabricated using the evaporation-spray coating process often exhibit significant hysteresis, which is attributed to the ease of ion migration and interface recombination in the perovskite produced by this method. To address this issue, we introduced butylamine additives containing different halide ions (I⁻, Br⁻, Cl⁻) into the spray process. After comparing the results, it was found that butylamine iodide (BAI) can effectively passivate lead and iodide-related defects in the perovskite by interacting with uncoordinated lead and iodide ions, thereby suppressing non-radiative recombination. Additionally, BAI promotes the transformation of PbI₂ during the evaporation-spray coating process, reducing the residual lead iodide in the perovskite. The wide-bandgap perovskite solar cells (energy gap (E_g), E_g ≈ 1.68 eV) fabricated using this method achieved a champion device photovoltaic conversion efficiency (PCE) increase from 16.61% to 19.91%. Furthermore, the unencapsulated devices demonstrated excellent stability, maintaining 80% of their initial efficiency after 450 hours of thermal aging at 60 °C.