A first principles study of the Ruddlesden-Popper layered perovskites A2MnO4 (A= Ca, Sr and Ba)

Abstract

Ruddlesden-popper layered perovskites A₂MnO₄ (A = Ca, Sr and Ba) in tetragonal phase (14/mmm) are studied through density functional theory (DFT). Structural properties as well as geometries are found consistent with the experiments. Magnetic stable phase optimizations in different antiferromagnetic (AFM) phases reveal that all these perovskites are G-type AFM. Electronic properties are investigated in G-type AFM phase; which shows that all these layered perovskites are semiconductors. A decrease in the bandgap (2.2 → 1.6 → 1.50 eV) is observed as going from Ca₂MnO₄ →Sr₂MnO₄ →Ba₂MnO₄. This decrease is arises due to the increase of the size of A cation. The optical properties show that all these perovskites are optically active in the infrared region, and could be used for optoelectronic devices. The elastic characteristics show that all these perovskites are mechanically stable, ductile and anisotropic in nature. The solar cell efficiency of these perovskites is simulated with WS₂ as ETL, MoO₃ as HTL and A₂MnO₄ are taken as absorber layers. The optimized FTO/WS₂/A₂MnO₄/MoO₃/Cu device expressed good solar cell performance with J_sc of 37.43, 38.40 and 40.77 mA/cm², V_oc of 10.641, 0.637 and 0.6152 V, value of FF is 65.90, 64.27 and 63.23 % and PCE is 16.01, 15.83 and 15.10 % respectively.