Effect of Speed of Spin Coating Deposition on Properties ofCH۳NH۳PbI۳ Organic- Inorganic Halide Perovskite

Lead halide perovskites have attracted considerable interest over the last few years asphoto absorbers in photo voltaic applications with record efficiencies now reaching۲۲%. Organic-inorganic halide perovskite based solar cells have been prepared bymeans of sequential spin-coating process. The spin-rate and step for PbI۲ as well asits concentration are important in determining the surface morphology of perovskite,and consequently, J−V performance. Perovskite absorber layer has been deposited byspin-spin process in which both lead iodide and methylammonium iodide precursorswere deposited by spin coating. Methylammonium iodide has been deposited by onestep and two step spinning program. One step deposition rate was ۳۰۰۰ rpm and twostep deposition rate varied from ۳۰۰۰ to ۵۰۰۰ rpm in second step. TiO۲ substratespreparation, lead iodide deposition, and annealing condition was maintained constantfor all samples. X-ray diffraction (XRD) and scanning electron microscopy (SEM)have been used to understand the importance of spin-coating parameters in perovskitesolar cells. Addition of deposition steps caused the formation of a relatively uniformperovskite layer and decreased grain size. Increasing spinning rate increasedcrystallinity and full conversion of perovskite. Thus, fully conversion of precursors toideal perovskite tetragonal crystal structure at room temperature was obtained byincreasing deposition step and speed of spinning deposition.

Keywords:

Perovskite solar cells , Control of morphology , Spin coating rate , Halideorganic-inorganic.