Strain‐Induced Distortions Modulate the Optoelectronic Properties of Epitaxial BiVO₄ Films

Abstract

Transition metal oxide (TMO) photoabsorbers are expected to play an important role in the development of renewable solar‐to‐fuel devices. Modest efficiencies have been demonstrated with devices based on TMO photoabsorbers, and further progress will likely rely on material property control beyond conventional bulk chemistry or nanostructuring strategies. To this end, model TMO photoabsorbers such as single crystalline monoclinic bismuth vanadate (BiVO4) are beneficial to advance the understanding of structure‐functionality relationships with minimal convoluted effects inherent in polycrystalline systems. Here, the authors reveal for the first time the effects of strain modulation strategies on the optoelectronic properties of epitaxial BiVO4 films synthesized by alternate‐target layer‐by‐layer pulsed laser deposition. Through a combination of high‐resolution X‐ray diffraction methods and optical and photoluminescence spectroscopies, the correlation between anisotropic, uniaxial strain‐driven bandgap widening and deviatoric strains associated with volume‐preserving lattice distortions is established. Broad polaronic photoluminescence signals are detected in epitaxial BiVO4, and its redshift is attributed to the structural distortion in BiO8 dodecahedra. Overall, the relationship between the structural and optoelectronic properties revealed in this study suggests that strain modulation and engineering of local distortion in complex transition metal oxides may be exploited as a viable strategy for the development of efficient photoabsorbers.

Behavior of Microstrain in Nd3+-Sensitized Near-Infrared Upconverting Core–Shell Nanocrystals for Defect-Induced Tailoring of Luminescence Intensity

“…Because of the advancement of the techniques for characterizing materials and nanotechnology, the effect of strain on nanoscale materials has become controllable for enhancing photocatalytic, optoelectronic, magnetic, semiconducting, and superconducting properties. − Such an approach, known as strain engineering, usually involves atomic level manipulation either inside or at the interface of crystal lattices. Mastering strain engineering requires a thorough understanding of the nature and the origin of lattice strain.…”