Suitability of K-doped (CH(NH2)2)x(CH3NH3)1-xPbI3 Perovskite Absorber for Energy Harvesting

Formamidinium lead iodide (FAPbI3) based perovskite solar cells are more promising than methylammonium based counterparts due to their higher thermal stability. But FAPbI3 film faces serious issue of photoactive phase instability at room temperature, hindering its usefulness as absorber in perovskite solar cells (PSCs). Recently, this problem has been well addressed through additive engineering. In this work, monovalent-cation engineering of FAPbI3 perovskite via MA+ (methylamine cation) and K+ (potassium cation) mixing is performed. We present a detailed analysis of effect of cation doping on structural and optical properties of formamidine based perovskite material. The structural and optical characterizations show positive effect of cation mixing on phase stabilization, crystallization, and absorbance of perovskite thin films. The crystallite size is found to increase on doping with a maximum for K0.05(FA0.83MA0.17­)0.95PbI3 sample. Also, the rise in absorbance in UV-Visible region of electromagnetic spectra is observed with doping.