Three structures of lead halide perovskite quantum dot (QD) solar cells with different absorbing layers of CsPbI3, FAPbI3, and CsPbI3/ FAPbI3 were simulated by SCAPS (Abdelaziz et al. in Opt Mater 10:10973, 2020; Karthick et al. in Sol Energy205:349–357, 2020; Verschraegen and Burgelman in Thin Solid Films 515:6276–6279, 2007). First, a device with a CsPbI3 QD absorber with a bandgap of 1.76 eV was simulated and power conversion efficiency (PCE) of 11.92% was obtained. Then, a device with a different absorber, the FAPbI3 QD layer with a band gap of 1.62 eV was simulated and we observed that the PCE was reduced to 9.50%. The narrower bandgap perovskite ( FAPbI3) leads to an increase in the short circuit current density from 13.22 mA/cm2 to 14.87 mA/cm2. Finally, the bilayer of the CsPbI3/ FAPbI3 structure was used as absorbing layers and a PCE of 18.55% was obtained. This increase in power conversion efficiency could be attributed to more efficient charge extraction. The physical mechanisms occurring in the devices were discussed in detail.
