action of the photovoltaic and triboelectric effects when the TENG was subjected to illumination.
Another implementation of the perovskite – nanogenerator hybrid device was the work of Zhang et al.. They demonstrated a HC made of SC, PyENG and TPiENG (Triboelectric- Piezoelectric Nanogenerator) as in Fig. 10(c). Lead zirconate titanate (PZT) perovskite which has both pyroelectric and photovoltaic properties was used to harvest both solar and thermal energies while a nylon and FEP film-based contact separation TENG was used to harvest the energies from both friction and vibration. The design paradigm adopted was a single structure multi-effects design made possible by the unique characteristics of PZT. The HC generated a peak current of 5 µA and peak voltage of 80 V while also being capable of charging a commercial 10 µF capacitor to 5.1 V in 90 s.
other research groups have employed varying the units of each component in the HC to better manage the discrepancy in power generated by the individual components of the HC. Improvements in switching, rectification and filter circuits and the development of a tailored composite circuit to tackle the issues inherent to PV-NG HCs would lead to a considerable improvement in HC efficiency by reducing the power losses involved in the electrical output conversion, modulation and transmission.
The consideration of newly developed SC technologies for HC integration – Bifacial solar cells are a case in point. The ability of these SCs to work with diffused and reflected radiation while also enabling the harvesting of radiation from multiple directions would lend themselves excellently to integration with NGs. The translucent properties of both the bifacial solar cells and NGs can be exploited to construct a multitiered sandwich structured HCs with improved energy utilization and power conversion efficiency. In addition, the capacity of bifacial cells to be mounted at considerably larger inclinations  would enable the NG components in the HC to harness a greater percentage of wind or raindrop electrostatic energies due to the increased angle of attack.
Long term performance and Life cycle analysis of PV-NG HCs – Long term performance of HCs with NG which rely on friction and/or moving components such as CS-TENG, moving electrode TENG, PENG and polymer-based HCs may deteriorate owing to the repeated mechanical stresses arising from operating conditions. Resilience tests are essential to determine the useful productive life of HCs and coupled with the carbon footprint of the fabrication process will enable the life cycle analysis (environmental impact assessment) of HCs. This is essential for HCs to compete against conventional green energy technologies since they are presented as a replacement/retrofit/advancement compared to the conventional solutions.
Improving degree of integration – Most PV-NG HCs employ some variation on the sandwich structure for integration. This results in a HC with physically distinct layers of SC and NG components. Methods of integrating both components in a single volume [41,43] may be investigated to reduce the HC footprint and improve the power density of HCs. The performance of TENGs is improved when the contact area increases which may be achieved by nano structuring the active layer to develop nanoscale roughness thus effectively increasing the contact area.
Investigation of synergistic effects – Recent studies[65,68] have remarked upon the synergistic effects of the simultaneous operation of the photoelectric and triboelectric effects in TENGs with perovskite materials integrated in them. This effect enhances the nanogenerator performance in the presence of light and allows for a more seamless integration of photovoltaic and nanogenerator technologies. Further investigation in this area is required to identify similar synergistic phenomena while also cogitating upon how to better exploit the currently identified photo-triboelectric effect in PV-NG HC design.
Table 2: Summary of PV-NG HC
Article PV Nanogenerator Method of Integration Output
Energy Harvested (in addition to
Solar energy) Xu et
al.,2009 DSSC, ZnO based PENG, ZnO based Serially connected on same Si substrate
NG- 0.01V 1.1 µA/cm2 PV – 0.591V 6.9 µA/cm2 NG+PV- 0.6V 6.9 µA/cm2
Vibration (ultrasonic) Lee et al.,
QDSSC (CdS/CdTe QD)
PENG Vertically aligned ZnO NW array
pn hetero junction of QD and NG with ITO and Au electrodes
PV- DC Isc 57 nA Voc 6 mV NG- AC 22-45 nA 1.5-6 mV
under 50 Hz sound wave Vibration (sound)
Xu and Wang, 2011
Solid-state DSSC PENG, vertical ZnO nanowire array
Convoluted back-to-back DSSC and PENG with ITO and GaN electrodes
DSSC+PENG serial connection- 34.5 µW/cm2 at Jsc 141 µA/cm2 and Uoc 0.243 V
Vibration (ultrasonic) Choi et al.,
coated PES) PENG (ZnO nanorod)
P3HT:PCBM polymer blend infiltrated nanorod array connected to the same substrate
Voc 0.55V Jsc 9.2 mA/cm2 – serially connected;
Mechanical (low frequency) Yang et al.,
Micro-pyramidal Si SC
CS-TENG (PDMS nanowire)
Protective glass coating of SC
replaced by TENG layer PV- Voc 0.6 V Isc 18 mA NG – 2.5 V rectified Wind Yang et al.,
BHPSC, ZnO – P3HT cell
PENG + PyENG, PVDF film based
Sandwich – SC + NG with ITO top electrode and Ag bottom electrode
NG – drove 5-digit LCD display
SC – under 1.5 AM with 100 mW/cm2 intensity, Voc 0.41 V, Isc 31 µA/cm2
HC- Li-ion battery charged to 1.5 V, drove 4 red LEDs connected parallelly
Thermal + mechanical (touch)
Zheng et al., 2014
TENG placed of top of PV and assembly secured with PDMS
PV under 12 W/m2- Voc 0.43V Jsc 4.2A/m2
NG at dripping rate 0.116 ml/s- AC Voc 30V Jsc 4.2mA/m2
Raindrop electrostatic Liang et al.,
S-TENG (transparent TENG) nanostructured
Nil (integration only proposed not demonstrated)
NG- maximum instantaneous power density of 11.56 mW/m2 at 5 KΩ load
At loads varying from 10 to 5 KΩ - Voltage 0.1 to 2.75 V and current 10 to 0.07 µA respectively
Raindrop electrostatic only
Zheng et al., 2015
Micro-pyramidal Si SC
S-TENG (ITO/PTFE) + CS-TENG (ITO/PTFE/PET)
Sandwich structure- Water TENG (S- TENG) + contact TENG (CS-TENG) + PV cell
NG- 86 mW/m2 from dripping rate of 13.6 mL/s 8 mW/m2 from a wind speed of 2.7 m/s
Wind + raindrop electrostatic Jeon et al.,
Conventional Si SC
S-TENG, PDMS micro-
bowl textured surface Sandwich- TENG + SC Hybrid cell- 7 V, 128 nA, Pmax 0.27 µW, Raindrop electrostatic Fang et al.,
BHPSC, PEDOT:PSS and
S-TENG, thin-film FEP Common electrode, SC deposited on S-TENG substrate
PV- Voc 0.74 V Jsc 5.8 mA/cm2 under AM 1.5
NG raised peak voltage to 1.9 V during combined operation
Mechanical (human body motions) Pu et al.,
Fibre-shaped DSSC (FDSSC)
CS-TENG, interdigitated Parylene
+ Ni (ELD coated)
FDSSCs and TENG woven onto the same fabric; TENG consisted of two sections: stator and slider
TENG- 3.2 W/m2 at sliding speed of 0.75 m/s FDSSC- PCE 6%, Jsc 10.6 mA/cm2 and Voc 0.6 V
Mechanical (human body motions) Chen et al.,
2016 FDSSC CS-TENG (F-TENG),
SC and TENG textiles are interwoven together
Hybrid cell capable of charging a 2 mF commercial capacitor up to 2 V in 1 minute
Mechanical (human body motions)
al.,2016 Si-based solar cell CS-TENG, Kapton/FEP/Cu
Sandwich- PV+TENG; to be installed on roofs
TENG- 26 mW with 1 MΩ impedance SC- 8 mW at 600 Ω resistance
After impedance matching via a transformer, 12 mA net
Wind Dudem et
DSSC CS-TENG, HNMA
TENG used to replace glass cover of SC; integration via common ITO/PET electrodes
HC - 18.2 V of output voltage and ∼ 1.4 µA of output current
at 0.5 Hz of external mechanical stimulus Mechanical +wind Wen et al.,
2016 FDSSC CS-TENG (F-TENG),
Sandwich- TENG + FDSSC + Fibre based Super Capacitor (F-SC)
FDSSC- Voc 0.74 V, Jsc 11.92 mA/cm2, PCE 5.64%
F-SC – specific capacitance 1.9 mF/cm
F-TENG – generated 0.91 µA from ambient human motions
Mechanical (human body motions) Zhang et al.,
2017 PZT based SC
CS-TENG, nylon/FEP + PENG + PyENG, PZT
One structure multi- effects construction
HC – peak current 5 µA, peak voltage 80 V, charged a 10 µF capacitor to 5.1 V in 90 s
Thermal + mechanical
Shao et al.,2017
Commercial water-proof Si SC
Sandwich- 1 SC+ 4 FS-EMGs + 4 CS- TENGs
At 0.2 to 2.0 Hz, 4 TENGs- 142 V Voc, 7.2 to 23.3 µA, P 4.4 to 31.5 µW; 4 series FS-EMGs- Voc 0.07 to 0.66 V, Isc 0.31- 2.14 mA, p 2 to 66.9 µW
Blue energy harvesting (Solar +
wind + wave energies) Liu et al.,
Heterojunction Si SC
Sandwich- SC+TENG with a mutual
electrode (PEDOT:PSS) TENG- Isc 33 nA, Voc 2.14 V Rain
Yoo et al., 2019
Conventional Si SC
TENG) Sandwich- MM-TENG+SC TENG- Voc 18.4 V, Isc 24.4 µA Rain
Cho et al., 2018
(QDSCs), PbS QDs
CS-TENG, P(VDF- TrFE-CTFE)
Sandwich- TENG + QDSC with Au bottom electrode and ITO top electrode
6 QDSCs + 1 TENG –
Charged a 35 mF capacitor by 215 mJ, corresponding to a power of 59.7 µW
Vibration Cao et al.,
CS-TENG – ITO (rotor) and FEP (Stator)
Cylindrical acrylic frame holds the rotor and stator, DSSC and soft Li- battery (SLB) placed along axis shaft
HC – 150 µA Isc at 200 RPM wind speed and 2mW light intensity; after charging for 0.88 h SLB discharged for 4.12 h at 10 µA discharge rate
Wind (rotational) Qian and
α-Si solar cell (UNISOLAR,
CS-TENG – PTFE/Al/Cu + EMG
TENG components split into stator and rotor placed coaxially along with EMG; SC wrapped around the rotor
Pmax – TENG (2.13 mW under 3 MΩ loading resistance),
EMG (0.34 mW under 10Ω) at 1200 RPM Wind (rotational) Ahmed et
Thin-film solar cell (Infinity PV,
Ltd., Jyllinge, Denmark)
PENG, LDT4-028K/L PVDF piezo film
PV+ artificial leaf + piezo film
Voc 5.071 V Isc 1.282 mA 3.42 mW at loading resistance of 5 kΩ; Charged 1000 µF capacitor when wind-driven
Wind + rain
Song et al.,
2019 FDSCC S-TENG, Silicone
FDSSC + TENG + flexible Super Capacitor (SC)
TENG- 130nC Voc 300 V
Isc 0.8 µA at 0.5 Hz to 1.6 µA at 2 Hz Pavg per cycle at 1 Hz 0.6 µW
SC charged in 35 s to 0.63V, 0.77V and 0.87 V at 0.5 Hz, 1 Hz and 2 Hz respectively
Liu et al.,
2019 Si SC S-TENG, nano wrinkled PDMS
Sandwich structure, WD TENG deposited upon SC
Nano wrinkled PDMS improved PCE from 12.55 to 13.57%
and WD TENG Voc and Isc increased by 385.5% and 299.1%
respectively compared to planar PDMS WD TENG
Ma et al.,
2019 α-Si SC, CS-TENG, ITO/ETFO
ETFO encapsulation to retain transmittance
SC- charged a 2.1 mAh Li-ion battery from 3V to 3.6 V under typical daylight of 25 mW/cm2
TENG – continued to raise the voltage of the cell to 3.86 V
Mechanical Ren et al.,
(P3HT:PCBM) S-TENG (GHF PDMS)
Sandwich structure with common electrodes (PEN/ITO); encapsulated in GHF film
HC – charged a 10 µF capacitor from 0 to 0.7 V in 400 s Mechanical Roh et al.,
2020 α-Si SC S-TENG, FEP/ITO + CS-TENG, PTFE/Al
Rain TENG (S-TENG) + SC + Wind TENG (CS-TENG) sandwich structure
Vmax - Rain TENG (5 V), wind TENG (50 V), SC (4.2 V) HC – charged a 0.1 µF capacitor to 14 V in 0.66 s
Wind + rain drop electrostatic
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
This work was supported by the Ministry of Higher Education, Government of Malaysia through its Fundamental Research Grant Scheme through grant FRGS/1/2019/TK10/TAYLOR/02/1.
This work was also supported by Taylor’s University through its Taylor’s PhD Scholarship programme.
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