Dimethylformamide-free synthesis and fabrication of lead halide perovskite solar cells from electrodeposited PbS precursor films

A multi-step dimethylformamide (DMF)-free green synthesizing method based on (i) initial electrodeposition of lead precursor, i.e. lead sulfide (PbS) on mesoporous TiO2/fluorine-doped tin oxide (FTO) conductive glasses substrates, (ii) subsequent conversion of PbS to PbI2 and (iii) synthesis of methylammonium lead triiodide (CH3NH3PbI3) perovskite film and their microstructural, optical and solar cell performance are described. Different electrodeposition techniques including direct current and cyclic voltammetry deposition were investigated to produce PbS films. We find that the perovskite films produced based on PbS deposited by cyclic voltammetry exhibit compact layer consisting of cuboid grains with an average size of approximately 800 nm and a bandgap of 1.58 eV whose properties are comparable to those of perovskite films generally prepared by conventional methods like spin coating. It was observed that uniform perovskite layers deposited under different conditions as the absorber layer generate a power conversion efficiency (PCE) of up to 7.72% under the standard AM 1.5 condition in the first attempt by this fabrication approach. PCEs obtained under different electrodeposition conditions were improved by eliminating of pores between the cuboid perovskite crystallites. This approach neglects employing hazardous solvents from the routine perovskite solar cell fabrication method and has potential to enhance its PCE similar to the common strategies by spin-coating methods improved over last decade by further modification of the electrodeposition process of the metal precursors and other steps towards highly efficient green perovskite solar cells.