Piezopotential generation in semiconductive ZnO nanowire (NW), oriented along the c-axis [0001], is significantly affected by free charge carriers within the ZnO NW. In this paper, the effect of free carriers' distribution in semiconductive ZnO nanowire is investigated, using a Finite Element Method (FEM). The mentioned effect leads to modification of the conduction band variation, carrier concentration profiles, and eventually, the magnitude and distribution of the piezoelectric potential. The impact of free charge carriers shows that the negative potential distributed at the tip of ZnO NW is decreased from V -270 mv for the donor concentration ND 1 10 15 C/m 3 to the V -25 mV, in presence of the donor concentration of ND 1 10 18 C/m 3. With selecting the appropriate electrical boundary conditions and applying the surface charges density at the top of the nanowire, the potential reduction is compensated. The electrostatic effect leads to a significant enhancement of the piezoelectric potential. The results are well shown the interplay of volume and surface charges and their influence on performance of nanogenerator, and so are crucial for designing of nanogenerators with high piezoelectric potential and good efficiency.
Thermoelectric (TE) devices are an interested family of energy harvesters which could convert the thermal energy into electricity. However, the temperature drops at interface between thermoelectric materials and heat source, heat sink and electrodes reduce efficiency of thermoelectric devices. As a solution, thermal interface materials (TIM) which have high thermal conductance and low thermal interface resistance with adjacent materials are added to the device. In this paper, the organic material is considered as the base material for a TE energy harvester device. Also, carbon nanotube (CNT) is applied as TIM, because of its high one dimentional electrical and thermal conductance. A finite element analysis is carried out in order to investigate the role of thermal contact resistance on heat transfer at TE device. To do this, a thermoelectric leg is simulated with two structure consist of (a) TE material and electrodes in direct contact (b) TE material and electrodes with CNT interface and the results are compared. It is shown that CNT layer reduces heat dissipation at the interface and so the temperature difference at the both sides of polymer is increased, which finally results the enhancement of device output voltage.
Piezoelectric nanogenerator (NG) made of nanowires (NWs) is a suitable device for harvesting ambient mechanical energy, applicable for self-powered electronic systems and nanodevices that operate at low power. The coupled piezoelectric and semiconducting characteristics of the zinc oxide (ZnO) NW cause an output voltage generation that made it interesting to use as an energy harvesting device in nanoscale. In this paper, the piezoelectric potential distribution in a bent ZnO NW is investigated, numerically. To do this, a three-dimensional finite element simulation of the device is performed and the results are analyzed and discussed. It is found that the output piezoelectric potential, for a constant nanowire length, is decreased as the diameter of ZnO NW increases. Study on the effect of NW diameters shows the potential will remain constant for nanowire with aspect ratio below 15. Further, the NWs are considered with an inclination of 20 degree relative to the substrate to study by applying force in different directions. The latter indicates an improvement on the output piezoelectric potential. The obtained results show that the ZnO NW can be used as a good energy harvester device by considering a suitable diameter, length and with a justified inclination angle.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.