Abstract The paper propose s a new and complex process for [615073]


Abstract – The paper propose s a new and complex process for
the (generation ) synthesis of ZnO nanoparticle s for antire flective
coating corresponding to silicone solar cells applic ations. The
process consists of two major steps: preparation of seed layer and
hydrothermal growth of Zn O nanoparticles. Due to the fact that
the seed layer morphology influence s the ZnO nanoparticle s
proprieties , the process optimization of the seed layer
preparation is necessary. Following the hydrothermal growth of
the ZnO nanoparticles , antireflective coating of silicone solar
cells is achieved . After determining the functional parameter s of
the solar cells provided either with glass or with ZnO, it is
concluded that all the parameters values are superior in the case
of solar cells with ZnO antireflection coating and are increasing
with the solar irradiance . (Also, ZnO nanowires antirefle ctive
coating show s an improved influence on the solar cell .)

Keywords – antirefle ctive coating, hydrothermal method, solar
cell, seed layer, ZnO nanoparticle s.

I. INTRODUCTION
INC oxide (ZnO) is characterized by a wide band gap of
~3.37 eV as well as by a high excitation binding energy of
60 meV . It can be processed either in bulk, thin film or
nanostructured forms, being suitable to many applications
ranging from optoelectronics to energy conversion, photo
catalysis and sensors [1 -4]. Due to its use, there have been
developed various methods for the preparation of high -quality
ZnO nanoparticles such as aqueous hydrothermal growth , [5],

1The rese arch was performed with the support of UEFISCDI, PNCDI II
Programme – Joint Applied Research Projects, Romania, Contract no.
63/2014, Environment energy harvesting hybrid system by photovoltaic and
piezoelectric conversion, DC/DC transformation with MEMS i ntegration and
adaptive storage. The research was also conducted within the National
Programme, Contract no. PN 16110105 /2016, T he impact of photovoltaic
power stations on the power quality within low voltage distribution grids .
Elena Chițanu , (e-mail: elena.chitanu@icpe -ca.ro ).
Lucian Pîslaru -Dănescu , corresponding author ,
(e-mail: lucian.pislaru@icpe -ca.ro ).
Lucia -Andreea El -Leathey , (e-mail: andreea.elleathey@icpe -ca.ro ).
Dorian Marin , (e-mail: dorian.marin@icpe -ca.ro ).
Virgil Marinescu, (e-mail: virgil.marinescu@icpe -ca.ro ).
Beatrice -Gabriela Sbârcea , (e-mail: gabriela.sbarcea@icpe -ca.ro ).
All t he authors are with the National Institute for Research and
Development in Electrical Engineering ICPE -CA, 030138, Bucharest,
Romania .

metal – organic chemical vapor deposition , [6], vapor phase
epitaxial , [7], vapor phase transport , [8], and vapor – liquid –
solid method [9]. The advantages of the hydrothermal method
of ZnO nanowire s synthesis over the previously mentioned
methods regard the fact that no special equipment is
necessary . Also, another important aspect relates to the
reduced cost of the process and to the uniformity of the
nanopa rticles on a large surface. The properties of the ZnO
seed layer play a significant role in obtaining high quality ZnO
nanowires by using the hydrothermal method . The film can be
deposited by a variation of methods: sol –gel method , [10],
spin coating , [11], magnetron sputtering , [12], or spray
pyrolysis [13].
Due to the optical proprieties of ZnO nanostructures, one of
its application s consists of antireflection coating for high –
efficiency solar cells. The surface texture leads to reduced
reflection , thus increasing the transmission of light by
scattering and also increasing the light coupling into the active
region of devices .
The paper presents a new and complex process designed for
deposition of ZnO seed layers. There are envisaged the
advantages of two methods, namely: the prevention of the
nanoparticles agglomeration and the enhanc ement of the ZnO
crystallinity by spray pyrolysis. In addition , the paper shows
the influence of ZnO antirefle ctive coating along with the
solar irradiance on the silicone so lar cells performance .
II. EXPERIMENTAL SETUP
ZnO nanowires have been grown by using the hydrothermal
method, consisting of a two -step process. The first step was
achieved by deposition of the seed layer through a complex
process while the second step has led to the growth of the
nanostructures, as shown within Fig. 1 [14] .
A. ZnO seed particles
In order t o obtain the ZnO seed layer , there was necessary
to develop a complex process that involv es two s tages : spray
pyrolysis and spin coating fo llowed by thermal treatment.
The ZnO seed layers were prepared by using zinc acetate
dihydrate [Zn(CH 3COOH) 2·2H 2O, Spolek Pro Chemickou,
10mM] as a precursor , dissolved in 1 -propanol [C 3H8O, Acros
Organics] by stirring at 50C for 30 minutes. The g lass
substrates were cleaned by using an ultrasonic bath. The
cleaning was firstly performed by using acetone and methanol Synthesis and Characterization of Antirefle ctive
ZnO Nanoparticles Coatings Used for
Energy Efficient Silicone Solar Cells
Elena Chițanu , Lucian Pîslaru -Dănescu1, Lucia -Andreea El -Leathey,
Dorian Marin, Virgil Marinescu, Beatrice -Gabriela Sbârcea
Z

afterwards. In the followings, there was used deionized water.
The glass substrates were then dried by blowing nitrogen on
their surf ace.
The d eposition of the ZnO seed layer has been undertaken
by using spray pyrolysis of 10 mM zinc acetate solution
(dissolved ) in 1-propanol. The glass substrate was placed on a
hot plate heated at 100°C. By u sing an airbrush, the layers
were sprayed on the substrate every 20 second s. The diameter
of the used nozzle was (equal to ) 0.5 mm while the distance
between the nozzle and the substrate was (equal to ) 15 cm .
During the deposition process , the rate of the solution flow
was maintained constant at 0.05 ml/min. Also, t he gas
pressure was equal to 3 bars . The number of layers has ranged
from 1 to 10 layers . After sp raying, the substrate was annealed
at 100°C for 30 minutes.
The s econd step regards the spin coating of the zinc acetate
solution (dissolv ed in 1-propanol ) on the substrate. The spin
coating was achieved at a rotation speed of 2000 rpm for 30
seconds. The substrate was then annealed at a temperature of
300C for 30 min utes in ambient air.
B. Synthesis of the ZnO nanostructures
The ZnO nanowires synthesis on the ZnO seed layer
substrates was developed through the hydrothermal process at
a temperature of 90°C by using zinc nitrate hexahydrate
[Zn(NO 3)2 6H 2O (purchased the ) CHIMOPAR] and
hexamethylenetetramine [C6H12N4 (purchased the )
REAC TIVUL ] as source materials. For synthesis, 20 mmol
Zn(NO 3)2 6H 2O was dissolved in 25 mL of deionized water .
Also, 20 mmol C 6H12N4 was dissolved in 25 mL of deionized
water. In the followings, the final solution was mixed and
heated at 90°C for 2 h ours in an electric stove along with
samples of ZnO seed layer substrates .

Fig. 1. Technological process regarding the ZnO nanoparticles [14].
Finally, the samples of ZnO nanowires were washed
thoroughly with deionized water, dried with nitrogen and
placed in a container at 25°C for 24 hours.
The structural analysis of the ZnO nanoparticles was
performed , (as shown in [14], ) by grazing incident X -ray
diffraction using an X -ray diffractometer (Bruker AXS D8
Discover ) with Cu and Kα irradiation, 40 kV/40 mA, 20 °- 60°,
2 Theta domain, 2 sec onds /step scan speed and 0.04 ° step. The
surface morphology and structure of the nanoparticles were
examined by employing a scanning electron microscope
(FESEM, Carl Zeiss Auriga) at an accelerating voltage of 2.00
kV. The imaging was performed at a high magni fication of
100 kx while the optical transmission and reflection spectra
was recorded in the wavelength range of 400 -800 nm by using
a double beam UV -Vis-NIR spectrophotometer ( UV-VIS
Spectrophotometer 570 Jasco) .
In the following stages, a commercial po lycrystalline
silicone solar cell manufactured by Conrad Electronic SE was
selected and covered by a nanostructured ZnO glass in order
to be tested. The technical data related to the considered
polycrystalline solar panel (123 cm2) consist of 1.35 W output
power, 9 V nominal voltage, 10.5 V open circuit voltage and
150 mA short -circuit current. The photovoltaic module was
tested for standard test conditions (1000 W/m2, 25°C, AM 1.5)
as well as for reduced solar irradiance by using the Pasan
Meyer Burger HighLight 3 solar simulator shown in Fig. 2 .
There w ere used 4 masks for the solar irradiance attenuation
(100 W/m2, 200 W/m2, 400 W/m2 and 700 W/m2) in order to
achieve the comparison between the generated power along
with varying the operation conditions . Accordingly, IV
characteristics resulted for each of the tested modules for
various operating conditions.

Fig. 2. Pasan Meyer Burger HighLight 3 solar simulator , view from radiation
source .
III. RESULTS AND DISCUSSION
The ZnO seed layers were prepared by using zinc acetate
dihydrate as a precursor , dissolved in 1 -propanol. The z inc
acetate is a salt of amphoteric zinc oxide and a weak acid like
the acetic acid [15]. The decomposition or hydrolysis of zinc
Glass substrate cleaned by using an ultrasonic bath: acetone,
methanol, deionized water and dried by blowing nitrogen
ZnO seed particles
1. 10 mM Zn(CH3COOH)2·2H2O in 1 -propano l
spray pyrolysis at 100o
C
2. Spin coating at 2000 rpm for 30 seconds

Hydrothermal synthesis of ZnO
nanostructures
Solution (Zn(NO3)2 6H2O and C6H12N4
90°C, 2 hours, electric stove

ZnO nanoparticles

salts represen ts an established route to the formation of ZnO
colloids and nanocrystals in aqueous solution [16 -18].
The further decomposition of the zinc acetate , in the
temperature region of 100 – 280°C, causes the formation of
Zn4O(CH 3COO)6, which finally decomposes into ZnO. The
gaseous products gener ated during the thermal process are
water (H 2O), carbon dioxide (CO 2), acetone ((CH 3)2CO) and
acetic acid (CH 3COOH), respectively. These products reached
their highest concentration at about 270°C, as the reaction
equati on (1)–(4) indicates . As the temperature increased, the
ZnO nanoparticles were formed by the following chemical
reactions:
  OH COOCHZn OH COOCHZn2 2 3 2 2 3 2 2.  
(1)
 
COOH 2CHCOOCHOZn O2H COOCH 4Zn
36 3 4 2 2 3
 
(2)

COOHCHZnO OH COOCHOZn
32 6 3 4
64 3

(3)

23 3 6 3 4
33 4
COCOCHCH ZnO COOCHOZn
 
(4)
Thus, the zinc acetate d ehydrate thermal process can be
considered a process of dehydration, vaporization /
decomposition and ZnO formation [19].
The synthesis of ZnO nanostructures or microstructures
from the Zn(NO 3)2-HMTA system has been reported in recent
years [20 -21]. It is generally considered as a very simple and
novel process. Understanding the growth mechanism of
different varieties of ZnO morphologies still needs further
improvement. Based on other researches, [22], the growth
process of ZnO crystallites is generally acc epted via the
following mechanism:
3 2 4 62 4 6 6 NH HCHO OH N CH  
(5)
  OH NH OH NH4
2 3
(6)
 2
43 32NHZn NH Zn (7)
 32
42
43 4 4 NH OHZn OH NHZn    
(8)
  2
424 OHZn OH Zn
(9)
  OH OH ZnO OHZn 222
4
(10)
In the aqueous solution of diluted ammonia, Zn(NH 3)4 and
Zn(OH) 42- are able to coexist. Therefore, Zn(OH) 42- is more
stable and can be formed from the transformation of
Zn(NH 3)42+, as shown in (8). In the dilute ammonia solution,
the amount of OH- is reduced (pH value around 10) and the
formation of ZnO nuclei l argely follows the reaction steps (5)
– (10). In this case, the formation of ZnO nuclei is slow and it
becomes the controlling step for synthesis of the ZnO films
[23].
The X -ray diffraction analysis was performed for the ZnO
seed layer as well as for the ZnO nanowires growth by the
hydrothermal method as shown within Fig. 3a and Fig . 3b. In
the case of the ZnO seed layer , there were identified only the
specific peaks of ZnO, confirming the higher purity of the
film. ZnO from seed layer presented wurtzite hexagonal
structure P63mc as well as structure parameters a = b = 3.242
nm and c = 5.176 nm. The intensity of the diffraction p eaks
corresponding to (002) and (110) plans displayed low broad
peak s in the case of all the analyzed seed layer samples.
The XRD analysis showed wurtzite hexagonal structure
P63mc and structure parameters a = b = 3.242 nm and c =
5.176 nm when also considering the nanowires. The
diffraction pattern highlighted peaks associated to (100),
(002), (101) and (102) plans and the correspondence of ZnO.
The (002) plan displayed a higher intensity peak in
comparison to the corresponding plans (100) , (101) and (102),
indicating that the ZnO nanowires are predominantly c -axis
orient ated. O ther peaks were not observed , leading to the fa ct
that n o other structures besides ZnO were formed. It was
confi rmed that high purity ZnO is obtained.

(a)
25 30 35 40 45 50 55 60
Intensity a.u.
2 Theta (degree)(002)
(110)
(b)
Fig. 3. XRD analysis of ZnO seed layer (a) and ZnO nanowires (b) growth by the h ydrothermal synthesis method [14 ].

(a) (b)
(c) (d)
Fig. 4. Scanning electron microscopy images of the ZnO seed layer (a ) and (c) and ZnO nanowires (b ) and (d) respectively , (100 kx
magnification ) [14].

During the experimental work, there was also conducted a
study regarding the influence of the seed layer morphology on
the nanowires proper ties. A different number of deposition s
(spray pyrolysis and spin coating) were achieved i n order to
determine the optima l thickness and morphology of the ZnO
seed layer. The optimal seed lay er was obtained by 3
application stages of spray pyrolysis at a temperature of
100°C, 3 stages of spin coating followed by treatment at 300°C
for a period of 30 minutes.
The microscopy micrographs shown within F ig. 4 were
recorded by using a field scanning electron microscope (Carl
Zeiss Auriga) or by employing the annular in -lens detector for
a second set of electron images with magnification of 100.000
X and an accelerating voltage of 2000 V.
The morphology of the ZnO seed layer surface influence s
the morphology of the ZnO nanowire. These layers operate as
seed crystals in order to ensure the epitaxial growth of ZnO
nanowires [24]. The morphology and growth of the zinc oxide
nanowires are influenced by the thickness and geometry of the
seed layer (uniform grain, 30 -55 nm) in the first case (as seen
from F ig. 4 a and b) . In the case of thicker films , ZnO clusters
are observed (grain s with dimensions larger than 100 nm)
consisting of agglomeration s that influence the nanowires
growth by a reduced order , scattered across the surface and
random orientated . In the second case ( Fig. 4 c and d) , due to
the seed layer uniformity and lack of agglomerations , the nanowires growth was orient ated, with homogenous
dimensions as well as displayed on the entire substrate
surface. In this case , there was obtained a perfect ly balanced
seed layer and also a homogenous nanowire growth with
lengths of ~20 0 nm and 50 nm diameter . Besides the high
density of the ZnO nanowire arrays, other nanostructures are
not observed .

400 500 600 700 800020406080100
T (%)
 (nm)glass
ZnO seed layer
ZnO nanowires

(a)

400 500 600 700 80005101520
R (%)
 (nm)glass
ZnO seed layer
ZnO nanowires
(b)
Fig. 5. Optical transmission (a) and reflection (b) of glass, ZnO seed layer and
ZnO nanowires film.

The variation of the optical transmission is shown within
Fig. 5 a, with wavelength found in the range of 400 – 800 nm
for glass, ZnO seed layer and ZnO nanowires. The ZnO seed
layer has presented a good transparency of approximately
80%, similar to the glass value due to the reduced thickness
(50 nm) and surface uniformity. The samples of ZnO
nanowires present a good transparency in the visible range
(400-800 nm), with a lower average value of 76%
(approximately 5% lower than in the case of glass). This
decrease is due to the fact that the transmitted radiation by
light diffusion increases the occurrence of the light scattering
phenomenon of the ZnO nanowi res.
Following the spectrophotometric analysis , the variation of
the optical reflection with wavelength in the range of 400-800
nm is presented in Fig. 5 b. The graph confirms that the
reflection is reduced in comparison to the values obtained for
simple g lass. The ZnO seed layer present s an intermediate
value be tween glass and ZnO nanowires, with an average of
11%. The average value of ZnO nanowires sample for the
visible optical reflection is equal to 9%, 5% lower than the
simple glass value (14.5%). By s ummarizing these optical
characteristics, it is concluded that the ZnO nanowire films
can be considered as a solution to the antireflective coatings in
the solar cells field due to the optical proprieties and low price
manufacturing.
The solar cells have b een tested , Fig. 6 -9, by using the SIM
3C HIGHLIGHT PASAN solar simulator for efficiency and
output power analyses . Also , the functional parameters
(efficiency, output power, open -circuit voltage and short –
circuit current) have been determined , as shown within Fig.
10-13, achieving analyses on the photovoltaic cells provided
with glass and ZnO nanowires. The used simulator is able to
adjust the irradiance value between 100 W/m2 and 1000 W/m2,
with both the light uniformity and light stability be low 1%.
The influence of the solar irradiance on photovoltaic cells
provided with glass and ZnO nanowires, related to efficiency,
output power, open circuit voltage and short circuit current is
shown in Fig. 10 – 13, suggesting that the functional
parameters depend on the solar irradiance and ZnO antirefle ctive coating , as suggested by the available literature
[25-26] .

Fig. 6. Conrad Electronic SE module IV curve for 200 W/m2 solar irradiance .

Fig. 7. Conrad Electronic SE module IV curve for 400 W/m2 solar irradiance .

Fig. 8. Conrad Electronic SE module IV curve for 700 W/m2 solar irradiance .

Fig. 9. Conrad Electronic SE module IV curve for 1000 W/m2 solar irradiance ,
[14].
The performance variation in the case of cells with ZnO
nanowires placed on glass was larger than the efficiency
variation in the case of the cell s covered with glass.
Consistently, the ZnO coated samples had a larger efficiency,
as shown within Fig. 10 suggesting that the reduced reflection
is correlated to more light being coupled into the active
material. The efficiency was increased from 7.79% for 100
W/m2 to 9.23% for 1000 W/m2 in the case of solar cell s with
simple gla ss. The efficiency has varied between 8.06% and
9.26% for solar cell s with ZnO nanowires on glass , for the
same values of irradiance . This increase is due to the
reflectivity of glass which is reduced by ~5% when applying
ZnO nanowires on glass.
0 200 400 600 800 10007.07.58.08.59.09.5
Efficiency (%)
Irradiance (W/m2) glass
ZnO glass

Fig. 10. Efficiency of the solar cell s with ZnO nanowires on glass (red), as
compared to solar cell s with simple gla ss (black) , for various irradiance
values .
0 200 400 600 800 10000.000.050.100.15
Isc(A)
Irradiance (W/m2) glass
ZnO glass
Fig. 11. Short circuit current of the solar cell s with ZnO nanowires on glass
(red), as compared to solar cell s with simple gla ss (black), for various
irradiance values .

All the solar cell’s parameters have increased along with the
irradiance ( values ranging from 100 W/m2 to 1000 W/m2) and
are superior in the case of the solar cell s with ZnO nanowires
on glass . The short circuit current increases from 0.015 A to
0.140 A for solar cell s with simple gla ss while in the case of
the solar cell s with ZnO nanowires on glass to values from
0.016 A to 0.141 A (Fig. 11); the open circuit voltage ranges
from 9.58 V to 10.92 V for solar cell s with simple gla ss and
from 9.66 V to 10.94 V for the solar cell s with ZnO nanowires
on glass (Fig. 12) .
0 200 400 600 800 10009.510.010.511.0
Uoc(V)
Irradiance(W/m2) glass
ZnO glass

Fig. 12. Open circuit voltage of the solar cell s with ZnO nanowires on glass
(red), as compared to solar cell s with simple gla ss (black), for various
irradiance values .

Also, the output power increased from 0.105 W to 1.134 W
for solar cell s with simple gla ss while for the solar cell s with
ZnO nanowires on glass from 0.109 W to 1.14 W (Fig. 13) .

0 200 400 600 800 10000.00.20.40.60.81.01.2
P (W)
Irradiance (W/m2) glass
ZnO glass
Fig. 13. Output power of the solar cell s with ZnO nanowires on glass (red), as
compared to solar cell s with simple gla ss (black), for various irradiance
values .

For each value in the range of irradiation of 100 W/m2 – 1000
W/m2, Fig. 11 -13, the values obtained in the case of the solar
cells wi th ZnO nanowires on glass are higher as compared
with the case to solar cells with simple glass.

Fig. 14 . The photovoltaic conversion system , functional model .

In Fig. 14 shows the photovoltaic conversion system,
functional model, in which used solar cells are with ZnO
nanowires on glass .
IV. CONCLUSION
The ZnO nanowires were prepared using the hydrothermal
method o f deposition on the seed layer by a new and complex
process . There are applied the advantages of two methods,
namely: the prevention of the nanoparticles agglomeration and
the enhancement of the ZnO crystallinity. During the
experimental work , a study was performed on the influence of
ZnO seed layer morphology on the proprieties of ZnO
nanowires. The resulting seed layer present ed suitabl e growth
proprieties by the hydrothermal method of uniform and
vertical ZnO nanowires. The performed XRD analysis on the
seed layer and nanowires confirmed a higher quality of ZnO
with wurtzite hexagonal structure. The SEM images of the
samples proved that the morpho logy of the ZnO seed layer has
a major influence on the dimensions and geometry of the nanowires. Also, the samples dispose of a un iform and
continuous film on the substrate. The ZnO nanowires present
uniform dimensions and geometry. The UV -VIS transmi ssion
and reflection spectra of the ZnO nanowires samples exhibit a
good transparency and a r eduction of the reflection by
approximately 5%. The determination of the solar cell’s
functional parameters (efficiency, short circuit current, open
circuit voltage and output power) has led to the conclusion
that all the values are superior in the case of the solar cell s
with ZnO nanowires on glass showing that the performance of
the solar cell depend s on the irradiance and antirefle ctive
coating . The results confirm the advantages of using the ZnO
nanowires in solar cells applications for antireflection
coating s.
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Elena Chitanu was born in Pitesti city,
Romania in 1978. She received the B.S and
M.S degree in chemical engineering from
University Politehnica of Bucharest in 2009
as well as the PhD degree in material
science field from Valahia University
Targoviste in 2013.
During the PhD studies, she colaborated with the research
team of CENIMAT – Centre for Materials Research
Department of Materi als Science, Nova University from
Lisbon, Portugal and from Institute for Organic Solar Cells
(LIOS), Johannes Kepler University from Linz, Austria. Since
2007 , she is a Scientific Researcher at the National Institute
for R&D in Electrical Engineering ICPE -CA Bucharest,
Romania, activating in the Advanced Materials Department.
Her research interests are in the area of thin film deposition
(chemical and physical), surface functionalization by chemical
method, films complex characterization and nanomateri als
chemical synthesis.
Lucian Pîslaru -Dănescu was born in
Timisoara, Romania, on March 14th,
1960. He graduated at 1985 and he
received Dr. degree in electrical
engineering from University
POLITEHNICA of Bucharest,
Romania, in 2005.
His employment experience include s the National Institute for
Research and Development in Electrical Engineering ICPE –
CA of Bucharest, Romania, Department of
Microelectromechanical devices and Department of Energy
Conversion and Consumption Efficiency, Research. The
research preoccupation includes: harvesting energy, with
energy sources such as piezo structures, photovoltaic and
electromagnetic structures, the models and prototypes
development for electromagnetic, piezoelectric and
magnetostrictive actuators, including the electronic sources for
actuators and the signal conditioning for sensors. Also,
development of electric generators that use superconducting
coils is considered. In addition, development of medium
voltage electric power transformers which u se a dilution of
magnetic nanofluid as a cooling agent, in order to improve
energy security, electromagnetic field computation and cryo –
electrotechnics as quench protection field i s the research
preoccupation too. Researcher ID: B-2894 -2013,
http://www.researcherid.com/rid/B -2894 -2013 , ORCID ID:
orcid.org/0000 -0002 -0255 -7473.

Lucia -Andreea El-Leathey was born in
Bucharest, Romania, on October 1st, 1987.
In 2010, she received the B.S. degree, while
in 2012, she received the M.S. degree, both
in the field of electric power engineering
from University Politehnica of Bucharest,
Romania. In 2016, she receiv ed the Ph.D.
degree in power engineering within
University Politehnica of Bucharest,
Doctoral School of Power Engineering.
From 2011 to 2015 , she was a Research Assistant with the
National Institute for Research and Development in Electrical
Engineering I CPE-CA from Bucharest, Romania, Department
for Energy Efficiency in Conversion and Consumption. Since
2015, she activates as a Scientific Researcher at ICPE -CA.
Her research interests include: the use of renewable energy
sources for electrical power genera tion, solar energy,
microgrids model ing, simulation and implementation as well
as smart grid.
Dorian Marin was born in Cluj -Napoca
(Romania), on June. 22, 1970. He graduated
the University „Politehnica” of Bucharest,
Romania in 1994 and received the Ph D
degree in electric engineering from the
same university in 2010.
His employment experience include s the National Institute for
Research and Development in Electrical Engineering ICPE –
CA of Bucharest, Romania, Department of Efficiency in
Energy Conversion and Consumption. Since 2007, h e is a

Senior Researcher at INCDIE ICPE -CA, activating within the
Laboratory of Photovoltaics . His research interests concer n the
electric machines, automation and electric grids . He is also
involved in photovoltaic modules’ implementation and testing.
Virgil Marinescu was born in 1978 in
Bucharest. He received the BS and MS
degrees from University of Bucharest,
Faculty of Physics in 2005. He is currently
pursuing the PhD degree school at Valahia
University of Tar goviste, Romania.
Since 2005 , he activates as a scientific researcher at the
National Institute for R&D in Electrical Enginee ring ICPE -CA
Bucharest, Romania, working within the Laboratory for
Electrical Materials and Products Characterization in
Advanced Materials Department. His research interests
concern complex characterization of materials (ceramics,
polymers , thin films, metal and alloys), optical microscopy,
scanning electron microscopy (SEM), EDX spectroscopy,
thermal behavior and stress fa ilure.

Beatrice -Gabriela Sb ârcea received the
B.S. degree in Medical Physics from
University of Bucharest, Faculty of
Physics, Romania, in 2006 and the M.S.
degree in Biophysics and Medical Physics
from University of Bucharest, Faculty of
Physics, Romania, in 2008. In 2013, she
received the PhD in the materials science
field.
Since 2007, she is a Scientific Researcher at the National
Institute for R&D in Electrical Engineering ICPE -CA
Bucharest, Romania, working within the Laboratory for
Electrical Materials and Products Characterization in
Advanced Materials Department. Her research interest
includes characterization o f metallic, ceramic and carbon
materials using a large area of characterization techniques: X –
ray diffract ion (Rietveld analyses on powder materials, thin
films characterization and bulk X ray measurements), optical
microscopy, determination of physical properties: methods for
density, granulometry, conductivity and micro -hardness
measurement.