Improving the optical absorption of BiFeO3 for photovoltaic applications via uniaxial compression or biaxial tension

Abstract

First-principles computations are employed to investigate the electronic structures and optical absorption of rhombohedral BiFeO 3 under uniaxial compression and biaxial tension. We find that the bandgap of BiFeO 3 is reduced under uniaxial compression, and it can be tuned to the ideal value for photovoltaic applications; furthermore, the indirect-to-direct bandgap transition occurs, which would lead to much enhanced optical absorption near the band edge. Similar results are found for biaxial tensile strain. Strong optical absorption is critical to build efficient solar cells based on ferroelectric thin films; strain engineering is thus a practical route towards realizing this scheme, in which no junction is needed to separate charge carriers. V

Perovskite Solar Absorbers: Materials by Design

“…f) Bandgap as a function of the uniaxial stress (−σ 33 ) with and without a scissor shift of the bandgaps by 0.54 eV (shifted data are indicated as corrected gap). Reproduced with permission . Copyright 2013, AIP Publishing.…”

“…Through DFT study of the effect of uniaxial compression and biaxial tension, Dong et al found that the bandgap of rhombohedral BiFeO 3 can be reduced to the ideal value of 1.34 eV for PV applications. Moreover, in this process, the bandgap is transformed from indirect to direct leading to an enhanced optical absorption, as shown in Figure f . Recently, Nechache et al investigated the multiferroic material Bi 2 FeCrO 6 (BFCO).…”

“…Moreover, in this process, the bandgap is transformed from indirect to direct leading to an enhanced optical absorption, as shown in Figure 8f. [167] Recently, Nechache et al investigated the multiferroic material Bi 2 FeCrO 6 (BFCO). By tuning the Fe/ Cr cationic ordering and the size of the ordered domain, the bandgap was reduced to 1.4 eV.…”

Ferroelectricity and Elasticity of Rhombohedral BiFeO3 Under Uniaxial Stress

“…The polarization increases nearly linearly from 75.5 to 97.1 μC cm −2 when the [111] stress changes from 8 to −8 GPa, which could tune the photoelectric, piezoelectric and ferroelastic properties of BiFeO 3 . When the polarization of BiFeO 3 increases from 75.5 to 97.1 μC cm −2 , optical absorption is expected to increase due to reduced band gap and the photocurrent is proportional to P , so that the photovoltaic efficiency will be significantly enhanced. On the other hand, piezoelectricity would decreases when P increases, because it is proportional to the elastic compliance coefficients.…”

Photovoltaic and magnetic properties of BiFeO3/TiO2 heterostructures under epitaxial strain and an electric field

“…Motivated by the enhanced PV properties in graphene/ polycrystalline BFO/Pt heterostructure [19], we suggest the BFO/ TO heterojunctions would possess an improved PV response due to the BPVE in BFO. Moreover, the PV effect and electronic properties in pure BFO can be engineered by electric field [20,21] and strain [22,23]. Therefore, a tunable PV effect by strain and electric field would be expected in the heterostructures.…”