Strategic advantages of reactive polyiodide melts for scalable perovskite photovoltaics

• Published in: Nature nanotechnology Vol. 14; no. 1; pp. 57 - 63
• Main Authors: Turkevych, Ivan, Kazaoui, Said, Belich, Nikolai A., Grishko, Aleksei Y., Fateev, Sergey A., Petrov, Andrey A., Urano, Toshiyuki, Aramaki, Shinji, Kosar, Sonya, Kondo, Michio, Goodilin, Eugene A., Graetzel, Michael, Tarasov, Alexey B.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.01.2019; Nature Publishing Group
• Subjects: 140/133; 140/146; 639/301/1005/1007; 639/301/357/404; 639/301/357/551; 639/4077/4072; 639/638/439/946; Chemistry and Materials Science; Energy conversion efficiency; Fabrication; Fluorine; Indium tin oxides; Iodine; Lead; Materials Science; Melts; Nanotechnology; Nanotechnology and Microengineering; Perovskites; Photovoltaic cells; Photovoltaics; Polyethylene; Polyethylene terephthalate; Solar cells; Substrates; Tin; Titanium dioxide
• ISSN: 1748-3387; 1748-3395
• DOI: 10.1038/s41565-018-0304-y

Despite tremendous progress in efficiency and stability, perovskite solar cells are still facing the challenge of upscaling. Here we present unique advantages of reactive polyiodide melts for solvent- and adduct-free reactionary fabrication of perovskite films exhibiting excellent quality over large areas. Our method employs a nanoscale layer of metallic Pb coated with stoichiometric amounts of CH 3 NH 3 I (MAI) or mixed CsI/MAI/NH 2 CHNH 2 I (FAI), subsequently exposed to iodine vapour. The instantly formed MAI 3(L) or Cs(MA,FA)I 3(L) polyiodide liquid converts the Pb layer into a pure perovskite film without byproducts or unreacted components at nearly room temperature. We demonstrate highly uniform and relatively large area MAPbI 3 perovskite films, such as 100 cm 2 on glass/fluorine-doped tin oxide (FTO) and 600 cm 2 on flexible polyethylene terephthalate (PET)/indium tin oxide (ITO) substrates. As a proof-of-concept, we demonstrate solar cells with reverse scan power conversion efficiencies of 16.12% (planar MAPbI 3 ), 17.18% (mesoscopic MAPbI 3 ) and 16.89% (planar Cs 0.05 MA 0.2 FA 0.75 PbI 3 ) in the standard FTO/c(m)-TiO 2 /perovskite/spiro-OMeTAD/Au architecture. Reactive polyiodide melt-assisted conversion of metallic lead nanolayers into hybrid lead halide films opens a new branch of scalable technologies for perovskite photovoltaics.