Fernandez, E.N.; van de Krol, R.; Abdi, F.F.: Tuning the Optical and Photoelectrochemical Properties of Epitaxial BiVO4 by Lattice Strain. Small Structures 5 (2024), p. 2400097/1-11
10.1002/sstr.202400097
Open Accesn Version
Abstract:
State-of-the-art photoelectrodes in highly efficient photoelectrochemical (PEC) systems often consist of multilayer architectures where lattice mismatch-imposed strain at the interfaces is likely to perturb the material’s crystalline lattice and electronic structure. Despite its inevitable presence, current understanding of the strain effects in semiconductor photoelectrodes is lacking, which prevents rational exploitation of strain engineering to improve photoelectrode performance. In this work, we combine X-ray based structural characterization methods with strain tensor decomposition analysis as well as optical and photocurrent spectroscopic methods to demonstrate how volumetric lattice deformations caused by substrate-imposed hydrostatic strain impact the optoelectronic and photoelectrochemical properties of BiVO4. Single-crystalline, epitaxial BiVO4/indium tin oxide (ITO)/yttrium-stabilized zirconia (YSZx, x = 8% and 13% mol Y2O3) photoelectrodes serve as a model platform, and we find that tensile hydrostatic strain that causes volumetric lattice dilation in BiVO4 results in slightly enhanced optical absorption. The increase in absorption properties, however, does not translate to increased photoelectrode performance. Instead, tensile hydrostatic strain is detrimental to the internal quantum efficiencies in BiVO4. We attribute this to localization of photogenerated charge carriers, thereby leading to poor charge separation in the bulk of BiVO4 and increased recombination losses. Finally, we highlight the beneficial effects of compressive hydrostatic strain on enhancing the internal quantum efficiencies in BiVO4. Our results provide a basis for exploiting epitaxial strain engineering to optimize the performance of multilayer photoelectrodes in PEC systems.