Utility of copper oxide nanoparticles (CuO-NPs) as efficient electron donor material in bulk-heterojunction solar cells with enhanced power conversion efficiency

Journal of Science: Advanced Materials and Devices 5 (2020) 104e110

Contents lists available at ScienceDirect

Journal of Science: Advanced Materials and Devices
journal homepage: www.elsevier.com/locate/jsamd

Original Article

Utility of copper oxide nanoparticles (CuO-NPs) as efficient electron
donor material in bulk-heterojunction solar cells with enhanced
power conversion efficiency
Hafsa Siddiqui a, b, *, 1, Mohammad Ramzan Parra a, c, 1, Padmini Pandey a, d, M.S. Qureshi a,
Fozia Zia Haque a, **
a

Optical Nanomaterial Lab, Department of Physics, Maulana Azad National Institute of Technology, Bhopal, 462003, India
Department of Physics, Sha-Shib College of Science and Management, Bhopal, 462030, India
Department of Physics, Govt. Degree College Boys Sopore, Jammu & Kashmir, 193201, India
d
Department of Physics, Savitribai Phule Pune University, Pune, 411007, India
b
c

a r t i c l e i n f o

a b s t r a c t

Article history:
Received 2 October 2019
Received in revised form

18 January 2020
Accepted 23 January 2020
Available online 12 February 2020

In the present work, we have endeavored the utilization of wet-chemically synthesized copper oxide
nanoparticles (CuO-NPs) as the active layer in hybrid bulk heterojunction (BHJ) solar cells. The BHJs with
CuO-NPs display significantly different physics from customary BHJs, and prove a noteworthy
improvement in their performance. It is noted that with the addition of CuO-NPs, the morphology of the
photoactive layer endures significant changes. Incorporating CuO-NPs is an additional paradigm for BHJs
solar cells which enhances the photocurrent density from 9.43 mA/cm2 to 11.32 mA/cm2 and the external
quantum efficiency as well. Also the power-conversion efficiency (PCE) improved from 2.85% to 3.82%
without harming the open circuit voltage and the fill factor. The enhancement in PCE achieved here
makes it worthy to design high-performance organic solar cells holding inorganic nanoparticles.
© 2020 The Authors. Publishing services by Elsevier B.V. on behalf of Vietnam National University, Hanoi.
This is an open access article under the CC BY license ( />
Keywords:
Bulk heterojunction
Solar cells
Copper oxide nanoparticles
Thin films
Photo current density
External quantum efficiency

1. Introduction
Currently, in order to adapt to the rapid development of electronic devices and electric vehicles, various energy storage materials are constantly being designed and developed. Bulk
heterojunction solar cells (BHJ-SCs) have many advantages such as
low cost of fabrication and an easy and simple fabrication process
with a wide range of applications. They have many tremendous
features such as transparency and the possibility of being fabricated
in different colors, thus being of interest for building-integrated

* Corresponding author. Department of Physics, Sha-Shib College of Science and
Management, Bhopal, 462030, India.
** Corresponding author. Optical Nanomaterial Lab, Department of Physics,
Maulana Azad National Institute of Technology, Bhopal, 462003, India.
E-mail addresses: (H. Siddiqui), foziazia@rediffmail.
com (F.Z. Haque).
Peer review under responsibility of Vietnam National University, Hanoi.
1
Equal contribution: Hafsa Siddiqui and Mohammad Ramzan Parra made an
equal contribution.

photovoltaics (BIPV) applications [1,2]. BHJs comprise of several
layers in which the photoactive layer plays a crucial role in
enhancing the overall photo-conversion efficiency (PCE or h). The
main challenging fact that is highlighted in the literature for BHJSCs is the poor light absorption mainly due to the small exciton
diffusion length and short carrier mobility [3]. To cover the visible
region of the solar spectrum, it requires compounds that strongly
absorb this range [4]. Therefore, a combination of inorganic nanoparticles with P3HT:PCBM (poly(3-hexylthiophene): phenyl-c61butyric acid methyl ester), have a potential to surpass in better
performance while retaining the benefits. Inorganic nanoparticles
have features as bandgap tunability, high absorption coefficient and
high intrinsic charge carrier mobility [5,6]. Moreover, previous
studies of solar cells that have directly incorporated inorganic
nanoparticles as electron acceptors i.e., ZnO, TiO2, or FeS2 nanoparticles, consist of light-harvesting absorbers, or light-scattering
centers using Au, Ag or PbS nanoparticles in conjugated polymer
films [7e9]. Compared to these inorganic nanoparticles, CuO
nanoparticles, a photo-generating material, have higher absorption
in the visible region and inject excess electrons to the structure

/>2468-2179/© 2020 The Authors. Publishing services by Elsevier B.V. on behalf of Vietnam National University, Hanoi. This is an open access article under the CC BY license

( />

H. Siddiqui et al. / Journal of Science: Advanced Materials and Devices 5 (2020) 104e110

[10e12]. Much research has been carried out in the field of catalyst,
sensor and energy conversion due to the contribution of CuO
[13e18]. The wide applications of CuO with controllable size, shape,
defect and dopant has intensely inspired many researchers. The
wide-range studies carried out show that the development of
cupric oxide (CuO) nanocrystals with modified architectures establishes a relationship between the structure and the properties of
CuO and its practical applications [19e22]. Hence, the P3HT donor
property could be tuned by generating electrons from the CuO
nanoparticles. M. Ikram et al. [23,24], E. Salim et al. [25]. and A. P.
Wanninayake et al. [26], used commercially available CuO nanoparticles to enhance the PCE of P3HT:PCBM solar cells.
Here, we have synthesized CuO-NPs (for experimental details
see electronic supporting information) by utilizing the wet chemical method and explained there structural, chemical and optical
properties and followed the photovoltaic performance by serving
them in P3HT:PC70BM in different concentrations (0%, 1%, 3%, 5%,
7%, and 10 wt. %). Without the addition of CuO-NPs a PCE of 2.84%
has been achieved for P3HT:PC70BM solar cells. However, a higher
efficiency of 3.82% is effectively achieved for CuO added
P3HT:PC70BM because of an efficient excitation generation, better
light absorption and a photoexcited charge separation and collection. The concept of the CuO-NPs fabrication and the use of them
into a P3HT:PC70BM photoactive blend is a noteworthy contribution. The systematic study with detailed discussion in the present

105

work is a first contribution towards the full understanding of such a
device architecture.
2. Experimental

All the experimental details are reported in Electronic Supporting Information (ESI).
3. Results and discussion
The XRD pattern of the prepared CuO nanoparticles (Fig. 1a)
confirms the formation of the pure monoclinic phase of CuO as all
the marked peaks are well indexed with JCPDS card no 80-0076. In
addition, the complete crystallographic information, as revealed
through a Rietveld refinement of the prepared sample, is given in
the supporting Information. The refinement pattern is illustrated in
Fig. 1b.
The micro Raman (m-RS) study further supports the microstructural (crystallographic) changes and various defect states
present in the prepared sample (Fig. 1c). The peak found at
288 cmÀ1 is assigned to the Ag mode, which corresponds to the
typical motion of the oxygen atom for displacement in the b-direction of the monoclinic structure of CuO (for details please see
[27]). Additionally, two peaks observed at 338 cmÀ1 and 624 cmÀ1
are attributed to the first-order Raman (Bg) modes.

Fig. 1. Characterization of the as-synthesized CuO-NPs (a) XRD patterns and (b) Rietveld refinement of the XRD pattern, (c) Raman spectrum, (d) full-scan XPS spectrum of CuO-NPs
and corresponding deconvoluted peaks in the high resolution spectra for Cu-2p (e), and O-1s (f) elements. Low (g) and high-resolution (h) TEM images and corresponding particles
size distribution is shown in the inset, and SAED pattern with all diffraction rings corresponding to indicate yellow CuO diffraction rings (i).


106

H. Siddiqui et al. / Journal of Science: Advanced Materials and Devices 5 (2020) 104e110

Further, the XPS survey scan does not include any chemicals
other than Cu, O, and C as shown in Fig. 1d. In addition (see Fig. 1e),
the core level scan spectrum of Cu2p shows a doublet with peaks
centered at ~934.9 ± 0.1 eV and ~954.3 ± 0.1 eV corresponding to
Cu2p3/2 and Cu2p1/2, respectively. These peaks are accompanied

with a set of satellites peaks at 962.2 eV, 941.3 eV and 943.6 eV
corresponding to Cu2þ state in CuO [28]. A spectral deconvolution
of the O-1s spectrum (Fig. 1f), results in two components appearing
at around 531.02 eV and 532.36 eV. The binding energy component
observed at 531.02 eV corresponds to the O2À ion in the CueO
bonds. The peak observed at higher binding energy at around
532.36 eV relates to oxygen vacancies in the CuO lattice.
Moreover, morphological investigations were performed using
TEM with low and high magnifications (Fig. 1g and f). TEM images
of the sample show size, shape and distribution of CuO-NPs as
uniform and homogeneous. The spherical nanoparticles have a
diameter of ca. 50 ± 2 nm (see inset Fig. 1g). A selected-area of the
electron diffraction pattern of CuO-NPs is indexed using C-Spot
software. The TEM diffraction pattern designates the presence of a
single crystal with a monoclinic structure (see Fig. 1i). The TEM
results are well in accordance with the XRD results.
Moreover, the optical band gap as well as the absorbance of the
as-prepared CuO-NPs is a key factor that has a major effect on the
performance of the prepared BHJs. The obtained absorption spectrum at ~836 nm corresponds to an energy of 1.47 eV (using tauc
relation detail is given in electronic supporting information and Fig
S1) and is blue shifted to the visible region as compared to the
reported absorption of CuO-NPs with an average particle size of
~50 nm (commercially available CuO-NPs) [23e26]. Therefore, a
better absorption of visible light is evidence of a better light
harvesting.
The above data confirm the pure phase formation of the prepared
CuO-NPs (detailed discussion above). These CuO-NPs were utilized

as a photo-absorber in the poly (3-hexyle thiophene) (P3HT) [6]:
phenyl-C61-butyric-acid-methyl-ester (PCBM) solar cell device

application. We were able to achieve a remarkable enhancement in
efficiency after inclusion of CuO-NPs. The performance of the asprepared CuO-NPs combined P3HT:PC70BM films were initially
examined in detail via AFM, XRD and UV-visible spectroscopy. The
relevant films were spin cast on quartz substrates [29]. The nanoscale morphology of pristine P3HT:PC70BM (Fig. 2a) and CuO
incorporated P3HT:PC70BM films (Fig. 2bec) confirm the surface
peaks of the CuO incorporated P3HT:CuO: PC70BM which are higher
as compared to pristine P3HT:PC70BM and infer an obvious increase
in surface roughness due to the addition of CuO-NPs. The rootmean-square roughness (RMS) value increased from 0.711 nm to
4.188 nm as the addition of CuO-NPs increased from 0 to 10 wt%. The
cell containing 5 wt% of CuO-NPs shows a surface roughness value of
2.402 nm, because of an increased nanoscaled phase separation
concerning the crystalline P3HT and the PC70BM acceptor [30,31].
However, the surface roughness of the film which contain 10 wt.% of
CuO may also increase the structural defects such as micro-cracks
(see Fig. 2c) which act as active recombination centers lead to increase the series resistance and lowering the Jsc an Voc values.
Optimal surface roughness gives more room for P3HT to
form, thereby increasing crystallinity. Furthermore, it can increase
the interfacial contact area between the PEDOT:PSS and
P3HT:CuO:PC70BM layer, allowing an efficient gathering of holes at
the anode and thereby improving current density (Jsc). The incorporation of CuO to the P3HT:PC70BM also affects the P3HT crystallinity as supported by the XRD results (Fig. 3a). The addition of
copper nanoparticles can improve the crystallinity of P3HT [24]. The
observed increase in crystallinity of the P3HT state seems to be
partially accountable for the rise in the absorbance and PCE of the
devices [23]. The Uv-visible absorbance spectra of pristine
P3HT:PC70BM and CuO incorporated P3HT:PC70BM (Fig. 3b) show

Fig. 2. 2D and 3D topographical AFM images of (a) pristine P3HT:PC70BM, (b) 5 wt%, and (c) 10 wt% CuO-NPs incorporated P3HT:PC70BM photoactive layer.


H. Siddiqui et al. / Journal of Science: Advanced Materials and Devices 5 (2020) 104e110

two absorption zones. The first zone below 350 nm was recognized
as PC70BM molecules while the absorption spectra from 350 nm to
650 nm (second zone) are related with poly (3-hexylthiophene)
(P3HT). The peak obtained at ~500 nm can attributed to the pep*
transition. The region below the absorption peak shows the light
harvesting ability of the photoactive layer [30]. The obtained peak
has exhibited a red shift ~510 nm after the incorporation of CuO-NPs,
because of the interruption of the structure and the orientation of
chain ordering of P3HT due to the CuO-NPs ability of light capturing.
In CuO incorporated photoactive layer blend, the absorption area is
enhanced from visible light to the near infrared area. The absorption
is enhanced by the increasing amount of CuO nanoparticles in the
active layer (Inset Fig. 3b).
Further, the performance of the as-prepared CuO nanoparticles
in P3HT:PC70BM solar cell was examined. The complete procedure
of device fabrication and testing as well as cell parameters is provided in the supporting information. The fill factor (FF), short circuit
current density (Jsc), open circuit voltage (Voc), power conversion
efficiency (PCE) and other related parameters were calculated using
the formulas as reported in refs [32,33] and a detailed comparison
of cell parameters is presented in Table 1. As earlier reports on the
OPV have proven, the active area and active layer thickness is
directly related to the power conversion efficiency (PCE) [34]. The
assembly of the organic photovoltaics based P3HT:PC70BM that was
utilized in this research is shown in Fig. 4(aeb). We have tried a
possible modification in the conventional architecture of [35]
P3HT:PC70BM solar cell by a successful incorporation of precisely
synthesized pure CuO nanoparticles. The possible band alignment
of pristine P3HT:PC70BM blend and CuO incorporated
P3HT:PC70BM ternary blend are presented in Fig. 4(ced) and are

well supported by the available literature [35]. Short circuit current
density versus open circuit voltage (J-V) characterization (Fig. 4e) of
pristine P3HT:PC70BM solar cell has been achieved with an ~2.85%
efficiency. From Table 1, it is obvious that after the incorporation of
CuO-NPs, Jsc increased from 9.43 mA/cm2 to 11.32 mA/cm2. This
indicates that the properties of the CuO-NPs affect the Jsc of the
device as well. Device parameters such as Jsc, Voc, and FF show
increasing behavior up to a certain (5 wt%) composition and then
decrease beyond this concentration. The power conversion efficiency follows the same trend, increasing from 2.85% to 3.82% and
then decreasing with further addition of CuO which may be due to a
higher aggregation of the CuO [8]. The aggregates let the solar cell
structure collapse and remove the network for charge collection.
Wanninayake et al. (2015) reported on the P3HT:PCBM solar cell
with CuO nanoparticles and obtained a value for the PCE of ~2.96%
[26]. In comparison with reported CuO incorporated P3HT:PC70BM
solar cells, our findings are novel and better because of the utilization of a cost effective synthesis method for preparing CuO-NPs
and by serving them as photo absorber for achieving enhanced
power conversion efficiency. Also, it is our belief, that this is the
maximal reported PCE based on a CuO incorporated P3HT:PC70BM
solar cell. In respect to device architecture, it is the most desired
approach for improving the absorption as well as Jsc of the prepared
devices. Further, the obtained results were compared with the reported P3HT:CuO:PC70BM solar cell (normal configuration) values
and are summarized in Table 2.
The effect of CuO-NPs inclusion is fairly well observed in the
series and shunt resistances as revealed from Fig. S2. The series
resistance (Rs) was 46 U for pristine P3HT:PC70BM. With an increase
in the CuO-NPs concentration to 5.0 wt %, the series resistance (Rs)
decreased to 11 U. Similarly, the maximal shunt resistance (Rsh) was
observed for P3HT:CuO5wt%:PC70BM, indicating a reduced
electronehole recombination rate and a leakage current due to the

presence of CuO-NPs [36]. The CuO-NPs may create a network
which can efficiently dissociate the exciton which results in the

107

Fig. 3. (a) The X-ray diffraction patterns of pristine and CuO-NPs incorporated
P3HT:PC70BM films. (b) The UV-Vis absorption spectrum of pristine and CuO-NPs
incorporated P3HT:PC70BM films, Inset enlarged x-axis in range 540e800 nm.

Table 1
Comparative analysis of device parameters of CuO incorporated P3HT:PC70BM solar
cell with pristine P3HT:PC70BM solar cell.
Fabricated devices

Voc (V) Jsc (mA/cm2) FF (%) PCE (%)

P3HT:PC70BM
P3HT:CuO1wt%: PC70BM
P3HT:CuO3wt%: PC70BM
P3HT:CuO5wt%: PC70BM
P3HT:CuO7wt%: PC70BM
P3HT:CuO10 wt%: PC70BM

0.56
0.57
0.58
0.59
0.56
0.52

9.43
10.24
10.84
11.32
10.11
6.38

54.01
56.92
56.12
56.76
52.55
44.96

2.85
3.43
3.53
3.82
2.98
1.49

±
±
±
±
±
±

0.02
0.01

0.03
0.02
0.04
0.02

EQE (%)
38
41
46
50
36
27

higher shunt resistance. The shunt resistance (Rsh) falls for higher
concentration of CuO-NPs.
In order to study the light harvesting capabilities of pristine
P3HT:PC70BM and CuO incorporated P3HT:CuO:PC70BM devices,
external quantum efficiency (EQE) spectra have been recorded
(Fig. 4f). More photons absorbed in the active layer
(P3HT:CuO:PC70BM) is one possible reason for the improved carrier
generation. The maximal efficiency of the EQE spectra shows the
same trend as Jsc and PCE. As expected, the cell P3HT:CuO5wt
%:PC70BM exhibited an extended photocurrent onset and showed a
marked improvement in EQE in the region of 400 nme750 nm,
compared to those of remaining (0%, 1%, 3%, 7%, and 10 wt% of CuO
nanoparticles) based P3HT:PC70BM devices. The maximal EQE of


108

H. Siddiqui et al. / Journal of Science: Advanced Materials and Devices 5 (2020) 104e110

Fig. 4. (a) Device structure. (b) Schematic diagram of the device structure (c, d) Energy level diagram of the component materials used for device fabrication using Ref [23e25]. (e)
Current densityevoltage (JeV) characteristics of pristine and CuO-NPs incorporated P3HT:PC70BM devices. (f) External quantum efficiency (EQE) and corresponding integral current
of the pristine and CuO-NPs incorporated P3HT:PC70BM devices.

the P3HT:CuO5wt%:PC70BM device was 50% at 550 nm which is
higher than the rest of the devices (Table 1). The higher absorption
range from 400 nm to 750 nm for the P3HT:CuO5wt%:PCBM device
followed the same trend as the EQE spectra and can be combined

with a similar variation of the absorption curve. The integrated Jsc
calculated from the EQE spectra (Fig. Fig. 4f) was slightly lower
(around 2%) compared to the Jsc value measured in J-V
characteristics and shows that the Jsc values are more trusting. We

Table 2
Few reports were found on CuO incorporated P3HT:CuO-NPs:PC70BM (Based on the Scopus data) till date with different configuration (normal and inverted) of solar cells.
Author

CuO-NPs

Cell Configuration

Type

PCE

Ref.

E. Salim

CuO-NPs
Sigma Aldrich
CuO-NPs
Sigma Aldrich
CuO-NPs
Sigma Aldrich
CuO-NPs nanocs.com USA
CuO-NPs nanocs.com USA
Wet chemically synthesized CuO NPs

ITO/ZnO/P3HT:CuO:PCBM/MoOx/Ag

Inverted

4.1

25

ITO/ZnO/(P3HT:CuO:PCBM/MoO3/Ag)

Inverted

4.09

23

ITO/ZnO/(P3HT:CuO:PCBM/MoO3/Ag)

Inverted

3.7

24

ITO/PEDOT:PSS (with Au-NPs)/P3HT/PCBM/CuO/Al
ITO/PEDOT:PSS/P3HT/PCBM/CuO-NP/Al
ITO/PEDOT:PSS/P3HT/PC70BM/CuO-NP/Al

Normal
Normal
Normal

3.5
2.9
3.82

36
26
Present work

M. Ikram
M. Ikram
A. P. Wanninayake
A. P. Wanninayake
H. Siddiqui, M. R. Parra


H. Siddiqui et al. / Journal of Science: Advanced Materials and Devices 5 (2020) 104e110

consider that the improvement in EQE and Jsc results from the
effective light scattering. Meanwhile, the FF value (56.76%) of
the P3HT:CuO5wt%:PCBM device is high, indicating that the
interface between the ITO/PEDOT:PSS and the active layer
(P3HT:CuO5wt%:PCBM) keeps a respectable contact quality, which is
also reflected by the Rs and Rsh values.

[4]

[5]

4. Conclusion

[6]

The present piece of work successfully fabricates P3HT:PC70BM
solar cells by incorporating wet chemically synthesized CuO
nanoparticles to adjust the morphology of the active layer by which
a significant enhancement of the device efficiency is achieved. It is
innovative to adopt wet chemically synthesized CuO nanoparticles
as an additive instead of the conventional organic high-boiling
compound. This is the novelty factor of this work. A power conversion efficiency of ~2.85% has been achieved for pristine
P3HT:PC70BM solar cells. However, a higher power conversion efficiency of 3.82% is effectively achieved for an optimal amount of
CuO-NPs added P3HT:PC70BM because of an efficient excitation
generation, better light absorption and a photoexcited charge
separation and collection. It is inferred that the incorporation of
CuO nanoparticles into the P3HT:PC70BM blend can efficiently
enhance the device performance which is validated by the EQE
study as well. Additionally, the shift in the absorption spectrum to

the visible region would help in a better absorption of light after the
incorporation of CuO-NPs in the P3HT:PC70BM blend. Such sort of
research paves the way to design an easy route for the synthesis of
copper oxide nanoparticles. Also, P3HT:PC70BM with an enhanced
efficiency may be useful for further optoelectronic applications.

[7]
[8]

[9]

[10]
[11]

[12]

[13]

[14]

[15]

[16]

[17]

Declaration of Competing Interest
The authors declare that they have no conflict of interests.
Acknowledgments
HS is thankful to UGC, New Delhi, India and MPCST Bhopal for

the award of MANF (F1-17.1/2011-12/MANF-MUS-MAD-4694) and
FTYS (File No: 83/CST/FTYS/2016). MRP acknowledges CSIR, New
Delhi for the award of SRF (ack. no. 163320/2K14/1). Authors would
like to thank Director CSIR-NCL, Pune, and are pleased to
acknowledge Dr. K. Krishnamoorthy, Scientist, Polymers and
Advanced Materials Laboratory, CSIR NCL, Pune for solar cell
fabrication and testing. The help rendered by Mr. S. Chithiravel is
highly appreciated. Authors are thankful to the Director-UGC-DAECSR, Indore Centre for performing material characterization and
grateful to Dr R. J. Choudhary for providing the XPS facility. In
addition, authors acknowledge Mr. Wadikar and Mr. Sharad Kumar
(AIPES, Beamline BL-2 Indus-1, RRCAT, Indore) for technical
assistance.

[18]

[19]

[20]

[21]

[22]

[23]

[24]

[25]
[26]

Appendix A. Supplementary data
[27]

Supplementary data to this article can be found online at
/>
[28]

References

[29]

[1] H. Siddiqui, Lead-free perovskite quantum structures towards the efficient
solar cell, Mater. Lett. 249 (2019) 99e103.
[2] M.R. Lee, R.D. Eckert, K. Forberich, G. Dennler, C.J. Brabec, R. Gaudiana, Solar
power wires based on organic photovoltaic materials, Science 324 (2009)
232e235.
[3] C.H. Kim, S.H. Cha, S.C. Kim, M. Song, J. Lee, W.S. Shin, S.J. Moon, J.H. Bahng,
N.A. Kotov, S.H. Jin, Silver nanowire embedded in P3HT:PCBM for high-

[30]

[31]

109

efficiency hybrid photovoltaic device applications, ACS Nano 5 (2011)
3319e3325.
S. Zhang, P.W. Cyr, S.A. McDonald, G. Konstantatos, E.H. Sargent, Enhanced
infrared photovoltaic efficiency in PbS nanocrystal/semiconducting polymer
composites: 600-fold increase in maximum power output via control of the

ligand barrier, Appl. Phys. Lett. 87 (2005) 233101.
B. Sun, H.J. Snaith, A.S. Dhoot, S. Westenhoff, N.C. Greenham, Vertically
segregated hybrid blends for photovoltaic devices with improved efficiency,
J. Appl. Phys. 97 (2005), 014914.
W.J.E. Beek, M.M. Wienk, R.A.J. Janssen, Efficient hybrid solar cells from zinc
oxide nanoparticles and a conjugated polymer, Adv. Mater. 16 (2004)
1009e1013.
P. Yu, S. Qu, C. Jia, K. Liu, F. Tan, Modified synthesis of FeS2 quantum dots for
hybrid bulk-heterojunction solar cells, Mater. Lett. 157 (2015) 235e238.
A.A.M. Velazquez, D. Canto-Reyes, J.A. Mendez-Gamboa, M. Acosta, Optical
absorption enhancement of P3HT:PCBM films through nanocavities using
polystyrene as a template, Mater. Lett. 245 (2019) 65e67.
H. Wang, W. Li, Y. Huang, Y. Wang, S. Yang, B. Zou, Efficiency enhancement of
organic solar cells by inserting PbS quantum dots film as the infrared absorption layer, Mater. Lett. 187 (2017) 136e139.
D. Yoo, D. Lee, J. Park, J. Ahn, S.H. Kim, D. Lee, Porosity control of nanoporous
CuO by polymer confinement effect, Scripta Mater. 162 (2019) 58e62.
X. Miao, S. Wang, W. Sun, Y. Zhu, C. Du, R. Ma, C. Wang, Room-temperature
electrochemical deposition of ultrathin CuOx film as hole transport layer for
perovskite solar cells, Scripta Mater. 165 (2019) 134e139.
H. Siddiqui, M.S. Qureshi, F.Z. Haque, Valuation of copper oxide (CuO) nanoflakes for its suitability as an absorbing material in solar cells fabrication,
Optik 127 (2016) 3713e3717.
J. Zhang, J. Wang, Y. Fu, B. Zhang, Z. Xie, Sonochemistry-synthesized CuO
nanoparticles as an anode interfacial material for efficient and stable polymer
solar cells, RSC Adv. 5 (2015) 28786e28793.
S.P. Lonkar, V.V. Pillai, S. Stephen, A. Abdala, V. Mittal, Facile in situ fabrication
of nanostructured grapheneeCuO hybrid with hydrogen sulfide removal capacity, Nano-Micro Lett. 8 (4) (2016) 312e319.
H. Siddiqui, M.S. Qureshi, F.Z. Haque, pH-dependent single-step rapid synthesis of CuO nanoparticles and their optical behavior, Optic Spectrosc. 123 (6)
(2017) 903e912.
H. Siddiqui, M.R. Parra, M.M. Malik, F.Z. Haque, Structural and optical
properties of Li substituted CuO nanoparticles, Opt. Quant. Electron. 50

(2018) 260.
H. Siddiqui, M.S. Qureshi, F.Z. Haque, Biosynthesis of flower-shaped CuO
nanostructures and their photocatalytic and antibacterial activities, NanoMicro Lett. 12 (1) (2020), 29, />S.C. Bhise, D.V. Awale, M.M. Vadiyar, S.K. Patil, B.N. Kokare, S.S. Kolekar, Facile
synthesis of CuO nanosheets as electrode for supercapacitor with long cyclic
stability in novel methyl imidazole-based ionic liquid electrolyte, J. Solid State
Electrochem. 21 (9) (2017) 2585e2591.
H. Siddiqui, M.S. Qureshi, F.Z. Haque, Hexamine (HMT) assisted wet chemically synthesized CuO nanostructures with controlled morphology and
adjustable optical behavior, Opt. Quant. Electron. 48 (7) (2016) 349.
M.A. Dar, S.H. Nam, Y.S. Kim, W.B. Kim, Synthesis, characterization, and
electrochemical properties of self-assembled leaf-like CuO nanostructures,
J. Solid State Electrochem. 14 (9) (2010) 1719e1726.
H. Siddiqui, M.R. Parra, F.Z. Haque, Optimization of process parameters and its
effect on structure and morphology of CuO nanoparticle synthesized via the
sol-gel technique, J. Sol. Gel Sci. Technol. 87 (1) (2018) 125e135.
B. Yuan, X. Liu, J. Liu, M. Li, D. Wang, Synthesis of different morphologies
CuO nanocrystalline under room temperature, Mater. Lett. 236 (2019)
495e497.
M. Ikram, M. Imran, J.M. Nunzi, S. Ali, Efficient inverted hybrid solar cells using
both CuO and P3HT as an electron donor materials, J. Mater. Sci. Mater.
Electron. 26 (2015) 6478e6483.
M. Ikram, M. Imran, J.M. Nunzi, Islah-u-din, S. Ali, Replacement of P3HT and
PCBM with metal oxides nanoparticles in inverted hybrid organic solar cells,
Synth. Met. 210 (2015) 268e272.
E. Salim, S.R. Bobbara, A. Oraby, J.M. Nunzi, Copper oxide nanoparticle doped
bulk-heterojunction photovoltaic devices, Synth. Met. 252 (2019) 21e28.
A.P. Wanninayake, S. Gunashekar, S. Li, B.C. Church, N. Abu-Zahra, Performance enhancement of polymer solar cells using copper oxide nanoparticles,
Semicond. Sci. Technol. 30 (2015), 064004.
L. Debbichi, M.C.M. Lucas, J.F. Pierson, P. Krüger, Vibrational properties of CuO
and Cu4O3 from first-principles calculations, and Raman and infrared spectroscopy, J. Phys. Chem. C 116 (18) (2012) 10232e10237.
H. Siddiqui, M. Shrivastava, M.R. Parra, P. Pandey, S. Ayaz, M.S. Qureshi, The

effect of La3þ ion doping on the crystallographic, optical and electronic
properties of CuO nanorods, Mater. Lett. 229 (2018) 225e228.
H. Siddiqui, M.R. Parra, P. Pandey, M.S. Qureshi, F.Z. Haque, Combined parametric optimization of P3HT:PC70BM films for efficient bulk-heterojunction
solar cells, J. Solid State Electrochem. 23 (12) (2019) 3267e3274.
H. Siddiqui, M.R. Parra, M.S. Qureshi, M.M. Malik, F.Z. Haque, Studies of
structural, optical, and electrical properties associated with defects in sodiumdoped copper oxide (CuO:Na) nanostructures, Mater. Sci. 53 (12) (2018)
8826e8843.
H. Siddiqui, M.S. Qureshi, F.Z. Haque, One step, template free hydrothermal
synthesis of CuO tetrapods, Optik 125 (17) (2014) 4663e4667.


110

H. Siddiqui et al. / Journal of Science: Advanced Materials and Devices 5 (2020) 104e110

[32] M.R. Parra, P. Pandey, H. Siddiqui, S.B. Qadri, F.Z. Haque, New-insight into the
physical properties of Zn1-xBxO two dimensional hexagonal nanodisks: an
efficient material for dye sensitized solar cells, Mater. Lett. 238 (2019)
194e197.
[33] H. Siddiqui, Modification of Physical and Chemical Properties of Titanium
Dioxide (TiO2) by Ion Implantation for Dye Sensitized Solar Cells, Ion Beam
(2019), In press, https://www.
intechopen.com/online-first/modification-of-physical-and-chemicalproperties-of-titanium-dioxide-tio2-by-ion-implantation-for-dy, 2019.

[34] W. Cao, J. Xue, Recent progress in organic photovoltaics: device architecture
and optical design, Energy Environ. Sci. 7 (2014) 2123e2144.
[35] A.D. Rao, M.G. Murali, A.V. Kesavan, P.C. Ramamurthy, Experimental investigation of charge transfer, charge extraction, and charge carrier concentration
in P3HT:PBD-DT-DPP:PC70BM ternary blend photovoltaics, Sol. Energy 174
(2018) 1078e1084.
[36] A.P. Wanninayake, S. Gunashekar, S. Li, B.C. Church, N. Abu-Zahra, CuO nanoparticles based bulk heterojunction solar cells: investigations on morphology

and performance, J. Sol. Energy Eng. 137 (3) (2015) 31016 (7 pages).