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Structure and Property Tunability in Monolayer Halide Lead-Free Double Hybrid Perovskites: Effects of Rashba and Biaxial Strain

Abstract

Organic-inorganic hybrid double perovskites (OIHDPs) are playing increasingly important roles in the development of stable and lead-free perovskite materials. However, most of them are indirect-band semiconductors with large band gaps which severely limit their development for practical applications. Here we theoretically investigate the intrinsic structures/properties and the biaxial strain-induced changes for monolayer lead-free OIHDP, MA4[AgBi]Br8 (MA=CH3NH3+), and propose to use strain to tune its electronic structures and optimize its properties. Our results show that the band structure of pristine MA4[AgBi]Br8 is indirect-band originated in the inequality spin-orbit coupling (SOC) effects on its valence and conduction band extrema and on two directions around the high symmetry point of the Brillouin zone, and that the strain tunes the band gap and the Rashba effect, as a result it mediates the band structure. The band gap of MA4[AgBi]Br8 varies linearly with the strain ratio and a ≥2 % stretching can turn it into a thorough direct-band semiconductor. MA4[AgBi]Br8 could perform different under various strain conditions. Compressing strengthens the giant SOC-related characteristic including SOC-induced indirect band gap and Rashba band-splitting while moderate stretching not only can lessen the band gap but also can enhance the carrier mobility and exciton separation, indicating that MA4[AgBi]Br8 has the potential to be a stable and non-toxic multifunational perovskite material. This work provides some full-scale insights into the the Rashba effect on band structures and the correlation between the structures/properties and the strain ratio.

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Publication details

The article was received on 13 Feb 2019, accepted on 09 Apr 2019 and first published on 10 Apr 2019


Article type: Paper
DOI: 10.1039/C9TA01647C
Citation: J. Mater. Chem. A, 2019, Accepted Manuscript

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    Structure and Property Tunability in Monolayer Halide Lead-Free Double Hybrid Perovskites: Effects of Rashba and Biaxial Strain

    Q. Liu and W. Liang, J. Mater. Chem. A, 2019, Accepted Manuscript , DOI: 10.1039/C9TA01647C

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