Model and performance analysis of energy conversion in functionally graded flexoelectric semiconductor nanostructures

• Published in: Applied mathematical modelling 2024-11, Vol.135, p.729-744
• Main Authors: Chu, Liangliang, Yang, Zuokun, Chen, Zhixing, Wu, Guibao, Dui, Guansuo
• Format: Article
• Language: English
• Subjects: Energy conversion efficiency; Flexoelectric effect; Functionally graded materials; Output electric power density; Semiconductor
• ISSN: 0307-904X
• DOI: 10.1016/j.apm.2024.07.023

•Multi-field coupling governing equations for non-homogeneous FS are built.•Energy harvesters consisting of FG-FS are studied.•Both the mechanical-electrical-semiconductive coupling and size-dependence are considered.•Electromechanical performances are improved at nanoscale due to the flexoelectric coupling.•Energy conversion behaviors can be tuned by physical parameters and the material nonuniformity. Energy systems converting efficiently from surrounding environment for powering semiconductor electronic components at nanoscale has attracted intense research interests. Due to the strong size dependency, flexoelectricity has been demonstrated as an excellent candidate implemented as nanoscale piezoelectric semiconductor energy harvesters. In this work, through a judicious exploitation of structural symmetry and nonuniformity, we theoretically study the energy conversion behaviors of a novel asymmetric nanodisk model composed of functionally graded (FG) flexoelectric semiconductor (FS) (FG-FS) materials while being loaded with thickness-extensional mechanical vibration. In numerical analysis, the material parameters have been treated with a general variation method under the Cartesian coordinate systems for simplicity. Taking into accounts of the nonuniform structural form and multi-field coupling features, we derived an octic governing equation with variable coefficients for the current analyzed FG-FS nanodisk structure, which is, however, almost impossible to obtain analytical solutions. To successfully address this issue and also further explore the improved performance and new phenomena induced by the FG type of non-uniform structural profile, we specially proposed an efficient tensor algorithm and reduced the octic governing equation into one quartic equation with variable coefficients and other four common quadratic equations. Later, we explicitly explored the effect of each physical parameter on the energy conversion performance of the FS energy harvester by studying the variations of the output electric power density and the energy conversion efficiency. Results illustrated that the electromechanical energy conversion behaviors of the studied FG-FS nanodisk can be properly tuned by not only the related material parameters but also their gradations. We believe our work have the potential to pave new way for the designs and manufacture of novel nano-electronic semiconductor components for the future practical applications.