Layer-By-Layer Printed Metal Hybrid (Cs:FA)PbI₃ Perovskite Nanocrystal Solar Cells

Mixed halide perovskite nanocrystals in the form of cesium/formamidinium lead triiodide ((Cs:FA)PbI₃) offer great potential for efficient and stable solar cells. To date, large-scale production with roll-to-roll compatible deposition methods remains difficult and requires detailed research on each involved processing step. Here, a proof-of-concept study about slot-die coating (printing) the active layer of (Cs:FA)PbI₃-based nanocrystal solar cells is presented. Structural and morphological changes during ligand exchange of long-chain oleic acid and oleylamine by Pb(NO₃)₂, and top-layer FAI passivation are investigated. Ligand exchange improves the processability of the nanocrystal layer and enhances charge transport. It also changes texture from face-on toward edge-on orientation as grazing-incidence X-ray scattering studies indicate. Ligand exchange and FAI passivation redshift photoluminescence and prolong charge carrier lifetime in the printed nanocrystal films. The proof-of-concept feasibility of printing metal halide perovskite nanocrystal films for solar cells is shown by building 20 devices with a median power conversion efficiency of 6.39%.