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

The TPPO additive precisely impedes the diffusion of organic salts and controls the formation process of evaporation-spraying perovskite layer, achieving one of the highest efficiencies of 20.93% and 16.73% on small-area device and modules, respectively. Premature perovskite films rapidly form at the FAI/PbI 2 interface, inhibiting further reactions between FAI and PbI 2 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 PbI 2 at the initial stage, which can be attributed to the hydrogen (H) bonds between FA + and TPPO , and coordinate bonds between TPPO and PbI 2 . Additionally, the quality of perovskite films improved significantly: the trap state density decreased from 1.6 × 10 18 to 3.17 × 10 17 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 cm 2 ) and 16.75% (63.7 cm 2 ), 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.