methods such as higher resolution, smaller device size, and so on. Obtaining high‐performance multifunctional material is still a challenge, and more research work is needed along this research direction.
1.4 Applications
Hybridized nanogenerators have extensive practical applications in environmental energies scavenging technologies and self‐powered sensor networks. Wind and solar energies can be simultaneously scavenged by the hybridized nanogenerators, consisting of TENGs and Si‐based solar cells. Moreover, the sizes of the hybridized nanogenerators can range from centimeters to hundreds of meters for harvesting large‐scale energies, pushing the potential applications of the hybridized nanogenerators instead of the conventional wind–solar energy harvesters in some environments. Moreover, the energy conversion efficiency is still a challenge for these energy scavenging devices. The stability of these hybridized nanogenerators in the natural environment still needs to be considered. Hybridized nanogenerators have been used as various self‐powered sensors, where the different nanogenerators can detect the different physical signals to realize simultaneous detection. Because different nanogenerators were used for detecting the different physical signals, no signal interference can be found in the detection process.
The coupled nanogenerators have potential applications in multi‐energies scavenging and multifunctional sensor systems. The core of the coupled nanogenerators is the multifunctional material; therefore, looking for a high‐performance material is one of the most important challenges for the applications. Ferroelectric materials‐based coupled nanogenerators have demonstrated the ability of scavenging multi‐energies from the environment, indicating that the coupled nanogenerators have better performances than individual energy scavenging devices. However, energy conversion efficiency of these devices still needs to be enhanced. Ways to obtain more electricity from these devices also need to be considered. For the application of multifunctional sensor systems, coupled nanogenerators exhibit more advantages than the conventional methods of integrating the different sensors in a system, such as smaller sizes, higher resolutions, and lower cost. The coupling effect among the different physical signals is very interesting due to the possible new mechanism. However, how to change the current/voltage in one circuit by the coupling needs to be investigated to quantify these signals in the multifunctional sensing process.
The hybridized nanogenerators have more chances to be used as a practical large‐scale energy scavenging technique as compared with the coupled nanogenerators. However, the coupled nanogenerators have more scientific significance than the hybridized nanogenerators, where the coupling enhancement among the different physical signals is interesting for future research.
1.5 Conclusion and Prospects
Hybridized nanogenerators integrating two or more different energy harvesting units into an energy scavenging system for simultaneously harvesting multi‐types of energies in our living environment have the potential for effectively enhancing the total output performance. It is one of the most significant multiple energies scavenging technologies. The development of hybridized nanogenerators is based on maximizing the harvested energy from one type of energy by integrating the different energy scavenging units and achieving complementary harvesting of multiple energies. The large‐scale hybridized nanogenerator consisting of solar cells and TENGs will be a very powerful technology such as creating new wind–solar complementary energies scavenging systems.
The core of the coupled nanogenerators is based on multifunctional materials such as ferroelectric materials. The coupled nanogenerators have the same materials and the same electrodes, which can obtain various advantages of smaller sizes, lower cost, and higher integrations than the conventional integrated different nanogenerators. The coupling enhancement effect among the different physical effects has been found in the coupled nanogenerators. Considering the highlighted advantages and the ongoing related research hotspots, more breakthroughs in hybridized and coupled nanogenerators with respect to the design, performance, and applications for multiple energies scavenging and self‐powered multifunctional sensor networks will be seen in future.
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