Hybrid Tribo-Piezo-Electric Nanogenerator with Unprecedented Performance Based on Ferroelectric Composite Contacting Layers

Abstract

It was recently reported that more efficient triboelectric nanogenerator (TENG)-like devices can be prepared using inversely polarized ferroelectric films made of same material as the contacting layers. In the present work, a clear correlation between the piezoelectric response of inversely polarized ferroelectric PVDF/ BaTiO 3 nanocomposite films and the performance of the TENG-like device based on these films is demonstrated. This observation is explained by magnified electrostatic induction that is driven by piezoelectric charges and ferroelectric properties of these films. A double capacitor model is proposed that effectively portrays the interactions between ferroelectric layers during contact−separation and subsequent charge redistributions in the external circuit. The new understanding has allowed the result of 3-fold higher open circuit voltages (2.7 kV from 5 cm 2) as compared to that of a state of the art TENG. Furthermore, findings uncover the potential for vast improvement in the field of nanogenerators for mechanical energy harvesting as a significantly better piezoelectric performance of flexible nanogenerators has been reported elsewhere.

Measuring Piezoelectric Output—Fact or Friction?

“…With improved polymer PEGs, hybrid PE-TEGs that harvest energy from both piezoand tribo-electric processes, thus attaining a much broader energy harvesting capability, can be developed effectively. [11,45,[50][51][52][53][54] There is excellent emerging research focussed on the development of such hybrid PE-TEG devices. [2,11,45,51,52,55] In particular, Woo-Suk Jung et al have shown clear evidence of the impact in optimizing both piezo-and tribo-electric components in PE-TEGs (Figure 6 c and d).…”

“…Overall in cases where the g 33 of the nanofiller is lower, any increase in voltage output would only be expected from changes in polymer crystallization (i.e., the percentage or alignment of the ferroelectric crystal phase) from polymer/nanofiller interactions, [44] or cases where the ceramic nanofillers are free to rotate. [45] Based on these concepts, it is expected that ultra-thin piezoelectric polymers containing ceramic nanofillers have a lower voltage output, unless the ceramic fillers are free to move and deform, and the fact this is not the case suggests the measurement of surface charge.…”

Transduction Mechanisms, Micro-Structuring Techniques, and Applications of Electronic Skin Pressure Sensors: A Review of Recent Advances

“…The most popular piezoelectric materials used in e-skin sensors, energy harvesters, and other types of sensors are lead zirconate titanate (PZT) [ 89 , 90 , 91 ], zinc oxide (ZnO) [ 68 , 87 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 ], barium titanate (BaTiO 3 ) [ 102 , 103 ], poly(vinylidene difluoride) (PVDF) and its co-polymers like poly[(vinylidenefluoride-co-trifluoroethylene] [P(VDF-TrFE)] and poly(vinylidene fluoride-co-hexafluoropropene) [P(VDF-HFP)] [ 88 , 99 , 102 , 103 , 104 , 105 , 106 , 107 , 108 ], and their piezoelectric coefficient, d 33 , can be found in Table 1 . The relation between the d 33 and the output of a piezoelectric sensor can be established by Equation (2): where V is the voltage produced by the sensor, C is the capacitance, and F is the force applied to the sensor [ 109 ].…”

“…PZT and ZnO are commonly integrated into sensors in the form of thin films or nano/micro-structures to minimize their brittle nature [ 54 , 87 , 89 , 91 , 97 , 100 ]. PVDF polymers are highly flexible, yet require a poling process to maximize their typically low d 33 constant [ 54 , 99 , 102 , 103 , 105 , 106 , 107 , 108 ]. The electrospinning of PVDF polymers fibers seems to eliminate the need of poling given that the process itself polarizes the polymer [ 104 ].…”

Combination of Piezoelectric and Triboelectric Devices for Robotic Self-Powered Sensors

“…Finally, the opportunities, challenges, and future expectations for PE sensors, TENG sensors, and PE-TENG hybrid sensors in the practical application of robot perception are introduced. [40,41]), TENG (reproduced with permission from references [42,43]), and PE-TENG hybrid (reproduced with permission from references [44,45]).…”