ZnO to power the nanogenerators, the first PENG [6]. Ever since there have been many
developments in the output device performance of PENGs, such as the output power density
P
(
)
d and some of these developments are summarized in Table 20.1.
20.3.1.2 TENG
This class of nanogenerators is based on the triboelectric effect. Certain materials are seen
to acquire electric charges after they are separated from a specific material with which it
was in contact. When two triboelectric materials are rubbed against each other, the sur
face connection increases; hence, the magnitude of triboelectricity [8]. The triboelectric
charges are seen to move to the surface when there is friction between the materials.
When these materials are separated, a potential difference is seen to develop between the
surfaces. The external free electrons usually move to screen the effect of this potential
difference that results in generating an electrical signal [8]. For a triboelectric nanogen
erator, the output parameters are measured by the following parameters [13]:
V
Qd
S
=
OC
r
(20.3)
I
dQ
dt
Q
I
dt
=
, such that
=
SC
SC
SC
(20.4)
where Q denotes the charge transferred, d is the displacement on sliding the surfaces, S is
the area of the opposite faces, r is the permittivity of the material used in the generation
of the TENG, and t is the time required in a complete cycle. To improve the TENGs’
performance, various polymers have been developed and used to achieve a high output.
TABLE 20.1
The Output Characteristics of PENG and TENG Fabricated Using Various Materials
Device
Materials
Matrix
Output performance
Ref.
VOC [V] Jsc [µA/cm2]
Pd [µW/cm2]
PENG
BaTiO3/carbon tubes
Polydimethylsiloxane
(PDMS)
4.6
1.84 µA
8.8
[ 9]
Graphene quantum dot/
Polyvinylidene Fluoride
(PVDF)
NA
6
25 nA
NA
[ 10]
Polyvinylidene Fluoride
trifluoroethylene P(VDF-
TrFE)/ZnO
NA
61
2.2 µA
NA
[ 11]
BaTiO3/Bacterial cellulose
NA
14
0.19
0.64
[ 12]
TENG
PVDF/Polyethylene
terephthalate (PET)
NA
1140
9.2
NA
[ 8]
Polytetrafluoroethylene
(PTFE)/PMMA
NA
233
3.18
NA
[ 13]
Fluorinated ethylene
propylene (FEP)/Acrylic
NA
1670
13.4
0.016
[ 13]
PDMS/PVA
NA
270.2
0.44
NA
[ 13]
Kapton/PET
NA
191
NA
8.75
[ 8]
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