Triphenylphosphine oxide additive regulates the growth of perovskite films by evaporation-spraying technique for high-efficiency large-area solar cell modules

Premature perovskite films rapidly form at the FAI/PbI₂ interface, inhibiting further reactions between FAI and PbI₂ during the fabrication of perovskite films via the evaporating-spraying hybrid method according to our previous research. In this research, triphenylphosphine oxide (TPPO) was proved to be an effective coordinator that reduces the reaction rate between FAI and PbI₂ at the initial stage, which can be attributed to the hydrogen (H) bonds between FA⁺ and TPPO, and coordinate bonds between TPPO and PbI₂. Additionally, the quality of perovskite films improved significantly: the trap state density decreased from 1.6 × 10¹⁸ to 3.17 × 10¹⁷ cm⁻³, while the crystal size increased from 740 to 940 nm. The champion perovskite device achieved a remarkable efficiency of 20.93% (0.09 cm²) and 16.75% (63.7 cm²), marking one of the highest reported results for the evaporating-spraying hybrid method. Moreover, the perovskite solar cells retained over 80% of their initial performances after 600 h of storage at 60 °C in a nitrogen environment without encapsulation. It also maintained approximately 90% of its initial performance after continuous illumination at 25 °C for 1400 h under the same conditions.