All-Vacuum-Processing for Fabrication of Efficient, Large-Scale, and Flexible Inverted Perovskite Solar Cells

Abstract

Vacuum deposition of transporting layers, especially the hole-transporting layer (HTL), is still a big challenge for the fabrication of large-area perovskite solar cells (PSCs). In this work, efficient and large-area PSCs are fabricated by thermal evaporation of all the layers. Poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine) (PTAA) is used as the HTL, and a compact layer of PTAA with low thickness (2–10 nm) is successfully deposited using thermal evaporation. The optical and ultraviolet photoelectron spectroscopy (UPS) measurements prove that the evaporated PTAA has a great match with the single A-cation methylammonium triiodide perovskite film in terms of quenching effect and band alignment. After fabrication of the inverted architecture using all-vacuum-processing, PSCs with power conversion of efficiencies (PCEs) of 19.4% for small area (0.054 cm2) and 18.1% for large area (1 cm2) are achieved, which are higher than those of solution-based devices. A flexible PSC with PCE of 17.27% is also fabricated using this approach. Moreover, the fabricated PSCs, using the vacuum technique, show negligible hysteresis and good stability, better than the devices fabricated on spin-coated PTAA. This work highlights the potential of vacuum deposition for scale-up and commercialization of PSCs.