Browsing by Author "Ahmadi-Kandjani, S."

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Embargo
Classical modeling of extrinsic degradation in polycrystalline perovskite solar cells defect induced degradation
(Elsevier BV * North-Holland, 2023-08-18) Mahiny, M.; Ahmadi-Kandjani, S.; Olyaeefar, Babak
In the realm of photovoltaic devices, the future appears bright for polycrystalline perovskite solar cells. However, the promise of their efficiency is threatened by a myriad of degradation mechanisms. These mechanisms, like dark spots on a sunny day, create shadows of uncertainty on the performance of polycrystalline PSCs. Nonetheless, this article comprehensively explains these degradation mechanisms and their impact on grain boundaries in PSCs. The paper investigates grain boundaries’ effects on carrier lifetime by employing various models, such as the Matthiessen rule and the Drude–Smith method. The findings reveal that defect density is the primary factor affecting the material’s performance, and grain boundaries’ size influences its changes. Drude–Smith’s model provides a more precise estimation of the mobility, total scattering lifetime, and PL quantum yield in polycrystalline semiconductors with reduced scattering time. The presented method is verified by feeding extracted parameters into Drift-Diffusion equations and fitting them with reported experimental photovoltaic conversion efficiency data. Furthermore, based on the simulation results and the strong correlation between grain boundaries and the time factor, the study proposes a comprehensive model that can effectively predict PSCs’ degradation time.
Open Access
Performance analyses of highly efficient inverted all-perovskite bilayer solar cell
(Nature Publishing Group, 2023-05-22) Gholami-Milani, A.; Ahmadi-Kandjani, S.; Olyaeefar, Babak; Kermani, M. H.
Numerical simulation of an all-perovskite bilayer solar cell has been conducted by the SCAPS-1D. The presented structure employs MAPbI3 as a relatively wide bandgap (1.55 eV) top absorber and FA0.5MA0.5Pb0.5Sn0.5I3 as a narrow bandgap (1.25 eV) bottom absorber. The viability of the proposed design is accomplished in two steps. First, to validate this study, two inverted solar cells in standalone conditions are simulated and calibrated to fit previously reported state-of-the-art results. Second, both these devices are appraised for the bilayer configuration to boost their performances. Affecting parameters such as the thickness of perovskite absorbers, the work function of front and rear contacts, and the effect of temperature have been studied because solar cells are temperature-sensitive devices, and also carrier concentration and their mobility get overwhelmingly influenced as temperature increases. It is manifested that using bilayer structures could easily widen the absorption spectrum to the near-infrared region and significantly enhance the performance of the device which is mainly affected by the thickness of the FA0.5MA0.5Pb0.5Sn0.5I3 layer. Also, it has been found that the work function of the front contact has a prominent role with its optimal values being above 5 eV. Finally, the optimized inverted all-perovskite bilayer solar cell delivers a power conversion efficiency of 24.83%, fill factor of 79.4%, open circuit voltage of 0.9 V, and short circuit current density of 34.76 mA/cm2 at 275 K and a thickness of 100 nm and 600 nm for MAPbI3 and FA0.5MA0.5Pb0.5Sn0.5I3, respectively.