Impact of nonparabolic electronic band structure on the optical and transport properties of photovoltaic materials
| Autor: | Lucy D. Whalley, Aron Walsh, Jarvist M. Frost, Benjamin J. Morgan |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Free electron model
Technology METAL HALIDE PEROVSKITES F300 Exciton Materials Science F200 FOS: Physical sciences Materials Science Multidisciplinary 02 engineering and technology Electronic structure H800 Polaron EXCITON 01 natural sciences 7. Clean energy Physics Applied ENERGY Condensed Matter::Materials Science Effective mass (solid-state physics) 0103 physical sciences SDG 7 - Affordable and Clean Energy CARRIER EFFECTIVE MASSES 010306 general physics Electronic band structure Physics Condensed Matter - Materials Science Valence (chemistry) Science & Technology Condensed matter physics Materials Science (cond-mat.mtrl-sci) CHARGE-CARRIERS PERFORMANCE Condensed Matter Physics 021001 nanoscience & nanotechnology cond-mat.mtrl-sci Electronic Optical and Magnetic Materials Physics Condensed Matter Physical Sciences Density functional theory 0210 nano-technology |
| Zdroj: | Whalley, L D, Frost, J M, Morgan, B J & Walsh, A 2019, ' Impact of nonparabolic electronic band structure on the optical and transport properties of photovoltaic materials ', Phys. Rev. B, vol. 99, no. 8, 085207, pp. 085207 . https://doi.org/10.1103/PhysRevB.99.085207 Whalley, L D, Frost, J, Morgan, B & Walsh, A 2019, ' Impact of non-parabolic electronic band structure on the optical and transport properties of photovoltaic materials ', Physical Review B : Condensed Matter and Materials Physics, vol. 99, no. 8, 085207, pp. 1-11 . https://doi.org/10.1103/PhysRevB.99.085207 |
| ISSN: | 2469-9950 |
| Popis: | 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 |
| Databáze: | OpenAIRE |
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