Impact of non-parabolic electronic band structure on the optical and transport properties of photovoltaic materials

Abstract

For semiconductors used in photovoltaic devices, the effective mass approximation allows calculation of important material properties from first-principles calculations, including optical properties (e.g. exciton binding energies), defect properties (e.g. donor and acceptor levels) and transport properties (e.g. carrier mobilities). The conduction and valence bands of semiconductors are commonly approximated as parabolic around their extrema, which gives a simple theoretical description, but ignores the complexity of real materials. In this work, we use density functional theory to assess the impact of band non-parabolicity on four common thin-film photovoltaic materials - GaAs, CdTe, Cu${}_2$ZnSnS${}_4$ and CH${}_3$NH${}_3$PbI${}_3$ - at temperatures and carrier densities relevant for real-world applications. First, we calculate the effective mass at the band edges. We compare finite-difference, unweighted least-squares and thermally weighted least-squares approaches. We find that the thermally weighted least-squares method reduces sensitivity to the choice of sampling density. Second, we employ a Kane quasi-linear dispersion to quantify the extent of non-parabolicity, and compare results from different electronic structure theories to consider the effect of spin-orbit coupling and electron exchange. Finally, we focus on the halide perovskite CH${}_3$NH${}_3$PbI${}_3$ as a model system to assess the impact of non-parabolicity on calculated electron transport and optical properties at high carrier concentrations. We find that at a concentration of 10${}^{20}$ cm${}^{-}3$ the optical effective mass increases by a factor of two relative to the low carrier-concentration value, and the polaron mobility decreases by a factor of three. Our work suggests that similar adjustments should be made to the predicted optical and transport properties of other semiconductors with significant band non-parabolicity.

Updated after review process

References in corpus (16)

• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• The NumPy array: a structure for efficient numerical computation
• Direct Measurement of the Exciton Binding Energy and Effective Masses for Charge carriers in an Organic-Inorganic Tri-halide Perovskite
• High-throughput electronic band structure calculations: challenges and tools
• Relativistic Solar Cells
• Relativistic quasiparticle self-consistent electronic structure of hybrid halide perovskite photovoltaic absorbers
• Low Hole Effective Mass p-type Transparent Conducting Oxides: Identification and Design Principles
• Lattice dynamics and vibrational spectra of the orthorhombic, tetragonal and cubic phases of methylammonium lead iodide
• Towards predictive many-body calculations of phonon-limited carrier mobilities in semiconductors
• Calculating polaron mobility in halide perovskites
• Slow cooling of hot polarons in halide perovskite solar cells
• First-principles analysis of electron transport in BaSnO${}_3$
• First-principles study on the effective masses of zinc-blend-derived Cu_2Zn-IV-VI_4 (IV = Sn, Ge, Si and VI = S, Se)
• Theory of Band Warping and its Effects on Thermoelectronic Transport Properties
• Accurate energy bands calculated by the hybrid quasiparticle self-consistent GW method implemented in the ecalj package

Cited by in corpus (11)

• VASPKIT: A User-friendly Interface Facilitating High-throughput Computing and Analysis Using VASP Code
• Lone pair driven anisotropy in antimony chalcogenide semiconductors
• Thickness dependence of electronic structure and optical properties of a correlated van der Waals antiferromagnet NiPS${}_3$ thin film
• Electronic structure and effective mass analysis of doped TiO${}_2$ (anatase) systems using DFT+$U$
• Quantifying polaronic effects on charge-carrier scattering and mobility in lead--halide perovskites
• Influence of crystal structure on charge carrier effective masses in BiFeO${}_3$
• High-throughput computational characterization of two-dimensional compositionally complex transition-metal chalcogenide alloys
• Three-dimensional bound states of cylindrical quantum heterostructures with position-dependent mass carriers
• Enhanced thermopower in two-dimensional ruthenium dichalcogenides $Ru{X}_2$ (X = S, Se): a first-principles study
• Effective particles in a multishell nanostructure with hardcore
• The quantum Hall effect under the influence of gravity and inertia: A unified approach