3.1. Optimization and Simulation of FASnI3 PSC
3.1.1. Effect of Temperature
The temperature of the solar cell has an effect on its overall performance. In this simulation, we kept the temperature constant at 300K at first and then varied it from 300K to 400K to determine the effect of working temperature on PCE, Voc, Jsc, and FF for the best ab-layer thickness, as shown in fig. In this simulated device, it was discovered that as the temperature increased, the PCE, Voc, Jsc, and FF of the solar cell decreased, because of carrier concentrations, charge carrier mobility and the material's bandgap at high temperatures (mariSoucase, et.al.2016). The efficiency slightly decreased from 24.09–23.64% at (300-400) K. The diffusion length reduces and series resistance increases. The resultant is decreased in PCE and FF (Mandadapu and group at 2017), because of the increase in energy enhanced recombination, electrons become unstable at higher temperatures in a solar cell, resulting in a low PCE (Mandadapu 2017). For that 340k is the working temperature for this simulation work.
3.1.2. The Effect of the Ab-layer Thickness
The ab-layer in PSCs absorbs photons from sunlight whose energy is greater than the bandgap of the ab-layer, which causes excisions. These preciseions are essentially charged electron-hole pairs. To maximize PCE, it is necessary to understand the impact of defect density on PSC performance. Because the Ab-layer is a critical factor in determining the performance of PSCs, its effect on solar cell output parameters has been studied using simulation. The active layer thickness was increased from 100 nm to 1050 nm in 850 nm increments and the effect on performance parameters is shown in Fig. (3). The device's performance is excellent at 850 nm, and it achieves the maximum efficiency. At 850 nm, the device's performance is excellent, with the maximum efficiency of 24.22% achieved by using Voc 6.20 V, Jsc 30.77 mA/cm2, and FF 12.68%.
3.1.3. Thickness optimized on Electron Transport Layer
Figure 4 illustrates the effect of ETL thickness and performance on ab-layer at 850 nm. When the ETL thickness is 20 nm, we get the best performance on the simulated device with the highest PCE of 24%, which is increased by 0.02% efficiency with FF of 12.68%, Voc of 6.20V, and Jsc of 30.77 mA/cm2.
3.1.4. Thickness optimized in Hole Transport layer
From Fig. 5. Shows the impact on the HTL and the device performance at 850 nm Ab-layer. When the thickness of the Ab-layer is at 850nm, we reach the maximum PCE 24.22% at 10 nm thickness of HTL with FF of 12.68%, Voc of 6.20V, Jsc of 30.77 mA/cm2.
3.1.5. Effect of Nt of the optimized device
In this simulation, the Nt of ab layered varied between 1012 cm−3 and 1018 cm−3 to find the best absorber thickness to find the variation in PCE, as shown in the Fig. 6,7,8 for the simulated device. PCE at other parameters of the simulated solar cell decreased as the absorber layer's Nt increased. As the defect density decreased, the efficiency stabilized at a certain point in this work, with the device performing well at 1016 cm3 (Nt) of absorber layer. The device performs best at 1018cm−3 and 1020cm−3 for ETL and HTL, respectively.
3.1.6. Effect of Bandgap in the simulation device
Sn-based PSC has a tunable band gap ranging from 1.3eV to 2.15eV. (vedanayakam, mandadapu.,2017). In this simulation, the bandgap of the optimized solar cell ranged from 1.2eV to 2.0eV for the best ab-layer to determine the variation in efficiency and other parameters. As shown in the figure 9, as the bandgap increased, PCE, FF, and Jsc decreased slightly while Voc increased. Jsc decreased as the bandgap increased, owing to less electron generation. After several simulations, the device was tested at 1.4eV. Similarly, we optimised the bandgap of ETL and HTL until we found the best performance of CuI at 2.8 eV and ZnOS at 2.4eV after several attempts. Figure 10 depicts the external quantum efficiency curve for the device's best absorber layer.