Stress effects on vibrational spectra of a cubic hybrid perovskite: A probe of local strain

Abstract

Inhomogeneous strain may develop in hybrid organic metal-halide perovskite thin films due to thermal expansion mismatch with a fabrication substrate, polycrystallinity or even light soaking. Measuring these spatially varying strains is difficult but of prime importance for understanding the effects on carrier mobility, non-radiative recombination, degradation and other optoelectronic properties. Local strain can be mapped using the shifts in vibrational frequencies using Raman or infrared microscopy. We use density functional theory to investigate the effect of uniaxial strain on the vibrations of pseudo-cubic methylammonium lead iodide (CH${}_3$NH${}_3$PbI${}_3$), and identify the vibrational modes most favorable for local strain mapping (86 cm${}^{-1}$, 97 cm${}^{-1}$, 1457 cm${}^{-1}$, and 1537 cm${}^{-1}$) and provide calibration curves. We explain the origin of the frequency changes with strain using dynamical matrix and mode eigenvector analysis and study strain-induced structural changes. We also calculate mode Grüneisen parameters, giving information about anharmonicity and anisotropic negative thermal expansion as recently reported for other phases. Our results provide a basis for strain mapping in hybrid perovskites to further the understanding and control of strain, and improve stability and photovoltaic performance.

arXiv comment41 pages, 10 figures

References in corpus (20)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• Phonons and related properties of extended systems from density-functional perturbation theory
• Optimized norm-conserving Vanderbilt pseudopotentials
• The PseudoDojo: Training and grading a 85 element optimized norm-conserving pseudopotential table
• Perovskite-perovskite tandem photovoltaics with optimized bandgaps
• Relativistic Solar Cells
• Lattice dynamics and vibrational spectra of the orthorhombic, tetragonal and cubic phases of methylammonium lead iodide
• Phonon anharmonicities in graphite and graphene
• Dynamic disorder, phonon lifetimes, and the assignment of modes to the vibrational spectra of methylammonium lead halide perovskites
• Optical transitions in hybrid perovskite solar cells: Ellipsometry, density functional theory, and quantum efficiency analyses for CH3NH3PbI3
• First principles calculation of vibrational Raman spectra in large systems: signature of small rings in crystalline SiO2
• Perspective: Theory and simulation of hybrid halide perovskites
• Spectroscopic Evaluation of Charge-transfer Doping and Strain in Graphene/MoS2 Heterostructures
• Dynamic Symmetry Breaking and Spin Splitting in Metal Halide Perovskites
• Structural and dielectric properties of Sr${}_2$TiO${}_4$ from first principles
• Stress effects on the Raman spectrum of an amorphous material: theory and experiment on a-Si:H
• Infrared nano-spectroscopy of ferroelastic domain walls in hybrid improper ferroelectric Ca${}_3$Ti${}_2$O${}_7$
• Multiple-stage structure transformation of organic-inorganic hybrid perovskite CH3NH3PbI3

Cited by in corpus (2)

• Surface Effects on Anisotropic Photoluminescence in One-Dimensional Organic Metal Halide Hybrids
• Bulk Assembly of Organic Metal Halide Nanoribbons