Multilayer methylammonium bismuth iodide perovskite solar cells (Bi-PeSC’s) were fabricated using multi-step spin coating by changing the spinning rates from 500 rpm to 5000 rpm with keeping the layer number at eight. The aim of this work is to study the effect of spinning rates on the multilayer Bi-PeSC’s performance. The SEM result shows the improved morphological properties at an optimum speed of spinning. At the same time, the XRD analysis exhibits that a very strong intensity and a narrow peak of MBI are observed at 12.67o (101) of 500 rpm, and it completely disappeared at 5000 rpm. The Dektak measurement showed that the thickness of multilayer Bi-PeSC’s is reduced from 600 nm to 300 nm as the spinning rates increased from 500 rpm to 5000 rpm. Furthermore, the multilayer Bi-PeSC’s showed an increment in the open circuit voltage with a maximum of 0.42V at an optimum spinning rate of 1000 rpm. The Bi-PeSC’s performance improvement is attributed to the formation of a moderate thickness of 568 nm. In brief, the spinning rate significantly influences the morphology, optical and structural properties of multilayer Bi-PeSC’s. In the future development of Bi-PeSC’s device, our research’s finding might have an appreciated contribution towards a better improvements of solar cells performance.
