In this study, SCAPS-1D is chosen over other simulation software due to a bunch of advantages including flexibility, a user-friendly environment, and more functionality. SCAPS-1D is a numerical simulation software for solar cell simulation, developed by Ghent University .The proposed all-perovskite non-toxic cell structure is given in Figure (a) and the band alignment of ETM, Absorber, and HTM is given in Figure ). During simulation, the solar radiation spectrum is set as AM 1.5G with 300 o K temperature, and illumination is set to 1000W/m 2 for the simulation. The hole thermal velocity and electron thermal velocity are 1E7 cm/s while band-to-band recombination is taken as 2.3E-9 Cm 3 /s. The optical absorption model is set up according to the new absorption model, here background, Step at Eg, sqrt() at Eg, power law 1, and power law2 all are used to have a perfect and relatively closer to a realistic model. The interface layer between HTM/Absorber and Absorber/ETM is also taken into consideration.