Sn(II)-containing phosphates as optoelectronic materials

Abstract

We theoretically investigate Sn(II) phosphates as optoelectronic materials using first principles calculations. We focus on known prototype materials Sn${}_n$P${}_2$O${}_{5+n}$ (n=2, 3, 4, 5) and a previously unreported compound, SnP${}_2$O${}_6$ (n=1), which we find using global optimization structure prediction. The electronic structure calculations indicate that these compounds all have large band gaps above 3.2 eV, meaning their transparency to visible light. Several of these compounds show relatively low hole effective masses ($\sim$2-3 m${}_0$), comparable the electron masses. This suggests potential bipolar conductivity depending on doping. The dispersive valence band-edges underlying the low hole masses, originate from the anti-bonding hybridization between the Sn 5s orbitals and the phosphate groups. Analysis of structure-property relationships for the metastable structures generated during structure search shows considerable variation in combinations of band gap and carrier effective masses, implying chemical tunability of these properties. The unusual combinations of relatively high band gap, low carrier masses and high chemical stability suggests possible optoelectronic applications of these Sn(II) phosphates, including p-type transparent conductors. Related to this, calculations for doped material indicate low visible light absorption, combined with high plasma frequencies.

10 pages, 10 figures, Supplementary information

References in corpus (10)

• BoltzTraP. A code for calculating band-structure dependent quantities
• CALYPSO: a method for crystal structure prediction
• Crystal Structure Prediction via Particle Swarm Optimization
• Low Hole Effective Mass p-type Transparent Conducting Oxides: Identification and Design Principles
• High Mobility in a Stable Transparent Perovskite Oxide
• Electronic Structure Calculations with the Tran-Blaha Modified Becke-Johnson Density Functional
• Band alignment at epitaxial BaSnO3/SrTiO3(001) and BaSnO3/LaAlO3(001) heterojunctions
• Band structure calculations of CuAlO2, CuGaO2, CuInO2 and CuCrO2 by screened exchange
• Tuning the properties of complex transparent conducting oxides: role of crystal symmetry, chemical composition and carrier generation
• Tuning Optical Properties of Transparent Conducting Barium Stannate by Dimensional Reduction