Effect Of Annealing Temperature On The Formation Of Methylammonium Tin Tri-Iodide Perovskite Thin Film

ABSTRACT

Organic-inorganic perovskite photovoltaics (PVs) have attracted a lot of attention as highefficiency thin film PVs which are relatively cheap and easy to fabricate. Lead halide perovskites have shown a rapid rise in power conversion efficiency by 3.8 % in 2009 to 21.02 % in 2016. One major problem is that lead is toxic and poses a serious concern to health and the environment. The most likely substitute for lead is tin. Tin-based perovskite solar cells have shown good semiconducting properties but still have very low efficiencies. The major challenge is the instability of tin in its +2 oxidation state. The photovoltaic performance and life span of these solar cells depend greatly on the film morphology. The morphology depends on the deposition technique and the subsequent treatment employed. In this work, we investigated the effect of post annealing temperature on the formation of methyl ammonium tin tri-iodide (CH3NH3SnI3). The SnI2/CH3NH3I was formed by sequential thermal evaporation of SnI2 followed by evaporation of CH3NH3I on a glass substrate. As-deposited SnI2/CH3NH3I films on glass substrate are annealed at different temperatures (80 oC, 90 oC, 100 oC, 110 oC, and 120 oC) in nitrogen atmosphere. Resistivity measurements and X-ray Diffraction (XRD) show that the best annealing temperature range for the formation of CH3NH3SnI3 may be between 80 oC and 100 oC.