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: Why Sn substitution should be preferred to Pb vacancy for optimum solar cell efficiency
摘要： Methylammonium lead halide (MAPbI3) perovskite has emerged as one of the frontier optoelectronic semiconductors. To avoid lead toxicity, the role of Sn substitution and Pb vacancy (Pb-(cid:2)) are addressed in regulating stability and solar cell ef?ciency of MAPb1?X ?Y SnX (cid:2)Y I3 perovskite using hybrid density functional theory (DFT). The role of spin-orbit coupling (SOC) and the electron’s self-interaction error are examined carefully. We ?nd to reduce the Pb content from pristine MAPbI3, Sn substitution has a more favorable thermodynamic stability than creating Pb-(cid:2). Moreover, on substituting Sn, due to strong s-p and p-p couplings, the lower parts of the conduction band gets shifted downwards, which results in the reduction of the band gap (direct). This further helps us to get a high optical absorption coef?cient (redshifted) and maximum solar cell ef?ciency in MAPb1?X SnX I3 for 0 < X (cid:2) 0.5.
关键词： spin-orbit coupling,MAPbI3,solar cell efficiency,Pb vacancy,thermodynamic stability,Sn substitution,Methylammonium lead halide,hybrid density functional theory,optical absorption coefficient
更新于2025-09-19 17:13:59
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Polarization-Direction Dependence of Thermodynamic Stability of Ferroelectric BiAlO <sub/>3</sub> (0001) Polar Surfaces
摘要： Polar surfaces of ferroelectric oxides are of great importance for both fundamental and practical interest. In this report, we present a theoretical study to determine the thermodynamic stability and electronic properties of ferroelectric BiAlO3(0001) surfaces. According to the calculated surface phase diagram, we predict that the equilibrium stoichiometries are distinct for the oppositely polarized BiAlO3 surfaces under the same chemical conditions. In addition to nonstoichiometry of the surface chemical compositions, we find that anomalous filling of the surface states can also result in surface metallization in order to compensate the remarkable surface polarity. Besides providing atomic-scale understanding of the BiAlO3(0001) surfaces, we also put forward the practical implications in novel magnetoelectric devices and advanced surface chemistry.
关键词： Magnetoelectric devices,Surface chemistry,Thermodynamic stability,Surface metallization,BiAlO3(0001) surfaces,Electronic properties,Ferroelectric oxides
更新于2025-09-09 09:28:46