Iodine Solution Treatment in Nonpolar Solvents as a Facile Approach to Improve the Morphology and Photostability of Perovskite Films.

We propose a new, simple, and easily implemented approach to improve the morphology of thin films of lead halide perovskites. A key feature of the approach is the controllable size increase of perovskite grains facilitated by polyiodides formed on the surface of the perovskite upon its treatment with iodine solutions in nonpolar solvents with the best results obtained for iodine solution in toluene saturated with MAI. Such a treatment demonstrated an increase in the average grain size of the films of up to 3.5 times in approximately 2 min followed by significantly enhanced photostability.

Patterned films of a hybrid lead halide perovskite grown using space-confined conversion of metallic lead by reactive polyiodide melts.

A unique technique for preparation of thin patterned perovskite films is suggested based on an interaction of reactive polyiodide melts with metallic lead coatings using a patterned die with a given relief. The growth of perovskite in confined space results in pin-hole free textured films.

Strategic advantages of reactive polyiodide melts for scalable perovskite photovoltaics.

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 CH3NH3I (MAI) or mixed CsI/MAI/NH2CHNH2I (FAI), subsequently exposed to iodine vapour. The instantly formed MAI3(L) or Cs(MA,FA)I3(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 MAPbI3 perovskite films, such as 100 cm2 on glass/fluorine-doped tin oxide (FTO) and 600 cm2 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 MAPbI3), 17.18% (mesoscopic MAPbI3) and 16.89% (planar Cs0.05MA0.2FA0.75PbI3) in the standard FTO/c(m)-TiO2/perovskite/spiro-OMeTAD/Au architecture.