Effects of Size and Morphology on the Excited-State Properties of Nanoscale WO3 Materials from First-Principles Calculations: Implications for Optoelectronic Devices

Abstract

Nowadays, the interest in tungsten oxide (WO3) nanomaterials for many light-driven technologies is significantly increasing due to their good biocompatibility, strong light absorption, and stabilized emission at room temperature. However, the poor understanding achieved on the photophysics of WO3 nanostructures, when compared to other prototypical nanomaterials, such as TiO2 , has largely mitigated their potential application as photoactive components in optoelectronic devices. In this context, we have developed a multiscale modeling approach to shed light on the excited-state properties (absorption and emission) of realistic WO3 nanoparticles (NPs) by means of time-dependent density functional theory (TD-DFT)-based methods. Upon validating our methodology against high-accurate perturbative methods and the available experimental data, we have demonstrated that the absorption and excitonic properties of the WO3 NPs can be easily tuned by controlling their size and shape. In the second step, our calculations pointed to the use of small NPs with a high density of surface atoms (i.e., spherical NPs) as the best strategy to enhance the emission properties of these NPs, demonstrating the importance of a judicious morphological design to improve the targeted optoelectronic properties in nanomaterials, thus opening the door to the practical exploitation of these materials in the field of optoelectronics.