Dynamical properties of organo lead-halide perovskites and their interfaces to titania: insights from Density Functional Theory

Abstract

The vibrational density of states (VDOS), electronic structure and optical properties of bulk organo lead-halide perovskites, CH 3 NH 3 PbX 3 (where X ¼ Cl, I and Br), very promising and exciting candidate materials for solarenergy applications, have been studied by means of (hybrid) Density Functional Theory (DFT), with and without spin-orbit coupling, and equilibrium Born-Oppenheimer molecular dynamics (BOMD) in the constantvolume, isothermal (NVT) ensemble at 298 K. Particular emphasis has been directed towards the detailed characterisation of optimal hybrid-DFT strategies to reproduce faithfully the band gap, band structure and optical properties vis-a-vis both experiment and more computationally demanding GW calculations (i.e., those involving the single-particle Green's function, G, and the screened Coulomb interaction, W). The VDOS was found to feature intimate coupling between the lead and halide atoms, and was dominated by acoustic phonon modesparticularly so for chlorine, suggesting this as the more effective candidate material of the considered halides. Bulk optical properties were also determined. In view of promising 'hybrid' architectures of perovskites adsorbed on titania substrates, further simulations of lead iodide in contact with titania have been performed to assess thermal stability, as well as dynamical and structural properties of these systems. It was found that lattice strain led to some atomic layers in perovskite further from the interface adopting less crystal-like structure and less pronounced phonon spectra.

Efficient Computation of Structural and Electronic Properties of Halide Perovskites Using Density Functional Tight Binding: GFN1-xTB Method

“…This is a considerable restriction since many of the most relevant and challenging advances in MHPs require the study of larger systems. These include alloys combining several cations, metals, and anions, the effect of the concentration of vacancies and defects in the crystal, the confinement of MHPs within porous materials such as silica matrices or metal–organic frameworks, and the interface of perovskites with other materials acting as charge-transport layers. , Classical simulations seem to be an “in part” solution to the above-mentioned size limitations of DFT calculations; however, they suffer from other drawbacks, such as the inability to simulate electrons and chemical reactions that are essential for the description of many properties of MHPs. Besides, classical simulations need a suitable and realistic force field, which is challenging to parameterize.…”

Ab-Initio Study of Electronic and Structural Properties for BaSnO3 Compound Using DFT Calculations and FP-LAPW Technique in Wein2k Software

“…an external potential of atomic nuclei Density Functional Theory is the most successful theory of today science and used for the study of the properties of system of electrons. The major advantage of the Density Functional Theory is reduction 3N degree of freedom of a system to three degree of freedom that made Density Functional Theory able to solve complicated system[20]. It gives ground state properties of material which further used to understand the behavior of that material with other materials, in general it gives the theoretical approach to the physical properties as well as electronic, optical, thermal, magnetic and electrostatic properties on the ground state level[21].…”