MINISTRY OF EDUCATION AND
TRAINING

VIETNAM ACADEMY
OF SCIENCE AND TECHNOLOGY

GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY

--------------o0o---------------

LE XUAN HUNG

STUDY SYNTHESIS AND OPTICAL PROPERTIES OF CdTeSe
NANOCRYSTALLINE AND CURCUMIN, ORIENTED APPLICATION IN
PHOTOVOLTAIC

Major: Optics
Code: 9440110

SUMMARY OF PHYSIC DOCTORAL THESIS

Ha Noi - 2018


This work was realized at: Graduate University of Science and Technology, Viet Nam Academy of Science
and Technology.

Supervisors:
1. Associate Professor - Doctor Pham Thu Nga, Institute of Materials Science-VAST.
2. Associate Professor - Doctor Nguyen Thi Thuc Hien, Duy Tan University.


than the bottom of the conduction band of TiO2 and high stability. Recently, the QD three-to-fourcomponent alloys is a promising choice, compared to the binary QD sensitizer, because their
photoelectric properties can be tuned. Their composition control without changing the particle size
and their bandgap is more narrow than that of the two-component system due to the "optical bowing"
effect. Today, in the testing of QD alloy as a sensitizer in QDSC, most aim at the CdTexSe1-x alloy
due to the absorption peak extending and shift to the near infrared region (NIR). The work of the
thesis is a new study, on the use of QD CdSeTe and CdTeSe / ZnSe alloys in solar cells. In Vietnam,
no group has mentioned the synthesis of ternary alloyed CdSeTe materials as we have in this thesis.
This is also the main content of the Nafosted project by our research group.
In terms of solar cells using dye (DSC), there have been some published works on the use of
a natural dye as a sensitizer for solar cells. This is one of the attempts to use "natural" resources to
serve for life. We also took advantage of this opportunity to study DSC, but PCE so far is still very
low. Recently, S. Suresh, et al. published solar cells using curcumin with an efficiency of 0.13%, S.J.
Yoon, et al. also showed PCE of about 0.11% when using only curcumin and up 0.91% when using
curcumin mixed with K2CO3. Very recently (6/2017), Khalil Ebrahim Jasim, et al. published solar
cells using natural curcumin dye to achieve 0.41% efficiency.
QDs are often synthesis in organic environments, so surface defects and ligand often appear
to reduce the luminescent quantum yield (QY) of the material. Therefore, QDs are often encased in
inorganic shells to passively surface, to improve QY. With the purpose of surface protection, CdTeSe
QDs are also coated with different shells, for example, covering the shell with a large band gap such
as CdS, ZnS. Besides, QD is also encased with buffer layer and CdS / ZnS shell to minimize lattice
defect, or cover the shell with ternary CdZnS alloys. In this thesis, we carried out the coverage of


2

CdTeSe QD with ZnSe and ZnTe shells, which are semiconductors, and have not been previously
published, for the purpose of applying the QDs in sensitized solar cells.
With natural dye, following the trend of using green energy for human service purposes, the
results of Zhou et al (2011) published using 20 different types of natural dye, to make sensitizers in
solar cells. In recent years, scientists have been interested in exploiting curcumin as a dye, intended

1.1. The semiconductor nanocrystals are quantum dots and ternary alloy quantum dots
The binary QD clearly shows quantization of energy levels and extends the bandgap when the
size of the QD decreases to a certain size in nm. With ternary alloyed QDs, optical properties in
addition to size dependence, they also depend on QD components. The non-linear dependence of
optical properties on the composition of some QDs is called the optical bowing effect.
1.2. Overview of natural curcumin colorants


3

Curcumin extracted from yellow turmeric consists of three main ingredients: curcumin
demethoxycurcumin (curcumin II), bisdemethoxycurcumin (curcumin III) and curcumin play a color
role for the compound and its yellow to bright orange color. Optical properties, as well as the physical
and chemical properties of curcumin, are specified in the chapter.
1.3. Structure, operating principle, and parameters affect the performance of solar cells
The structure of a sensitizer solar cell was introduced. The charge transport model, as well as
the parameters affecting PCE are designed to find the optimal conditions for assembling components.
CHAPTER 2.
METHODS OF SYNTHESIS MATERIALS AND EXPERIMENTAL TECHNIQUES
2.1. Synthesis of CdTeSe quantum dots and CdTeSe/ZnSe (ZnTe) core/shell structure
The whole process of manufacturing QD in ODE-OA media is summarized in figure 2.1
diagram.

Figure 2.1. Diagram of synthesis CdTeSe QD in ODE-OA media

The process of covering ZnSe or ZnTe shell for CdTeSe is similar and according to the
diagram of figure 2.3.

Figure 2.3. Diagram of synthesis QD core/shell in ODE-OA media


the working electrode and the electrode to transmit the carrier particles. The counter electrode is
usually a layer of conductive glass coated with a catalyst (Pt, Au, Cu2S or MWCNT), to exchange
the charge between the counter electrode and electrolyte. The entire assembling process is given in
the diagram figure 2.8.
Research results on coating TiO2 film on the photoelectrode
Surface SEM images of TiO2 films prepared after heating at 450 oC for 30 minutes, with
different resolutions showed that TiO2 film surface is uniform, no flakes or cracks appear (figure
2.9a). Surface SEM images of TiO2 films (figure 2.9b) show that the TiO2 particles are bonded
together to form a porous structure, which helps to absorb dye or QDs.

(a)

(b)

(d)

(c)
8,93µm

16,5µm

Figure 2.9. TiO2 film surface image with magnifications of 35 times (a), 50000 times (b) and crosssection image of TiO2 film in 1time coating (c), 2 times coating (d) taken with SEM image

The SEM image of the cross-sectional surface of TiO2 film is coated with the Doctor-Blade
technique, which shows that at 1times the thickness of the film is 8,93 µm (figure 2.9c) and twice the
thickness of the film is about 16.5 µm (figure 2.9d). Thus, with the Doctor - Blade technique with 2
overlaps, the results show that our TiO2 films are suitable for making photoelectrode in solar cells.
Research results on MWCNT – TiO2 film on counter electrodes by SEM
SEM images show that the film thickness is about 20.4 µm, the link between the MWCNT –
TiO2 film and the FTO layer, as well as the glass, is good. The MWCNT is interlinked and linked to


Figure 3.3. Absorption and fluorescence
spectra of samples with different initial molar ratio


7

The absorption and fluorescence spectra of samples with different molar precursors are given
in figure 3.3. From figure 3.3, we observe that the exciton absorption peak corresponds to the 1Sh3/2
→ 1Se basic absorption transfer. The fluorescence spectrum of the samples has a maximum of 680
nm and 668 nm, respectively, with a molar ratio of 1: (1,8: 1,8) and 10: (1: 1). The spectral width
(FWHM) of the samples is 57 nm and 50 nm respectively, narrower than the reports of QDs of the
same type in the infrared region. This result shows that the synthesized QDs are of good quality.
Thus, the molar ratio of the initial substances is 1:(1,8:1,8), the system will tend to produce
QDs that are very rich in CdTe. This can be explained as follows: in the same synthesis condition of
QDs, the reaction of Te and Cd is much faster than that of Se with Cd. Due to the difference in
reaction, CdTe's development speed is 2 times faster than CdSe. When the molar ratio of the initial
substances is 10:(1:1), during the reaction process there is always Cd residue, so the Se have the
opportunity to participate in the reaction to create the ternary alloy CdTeSe QDs
3.2. Effect of grown temperature on the properties of quantum dots
3.2.1. Morphology and crystal structure
Figure 3.4 shows the X-ray diffraction
spectrum of CdTeSe QDs manufactured
according to the diagram of figure 2.1, in ODEOA media, the ratio of initial precursor 10:(1:1),
grown at different temperatures, from 180 oC to
280 oC, for 10 minutes. The diagram of X-ray
diffraction shows that all diffraction peaks are
expanded more than the bulk material. This
indicates that fabricated QDs have nano size. The
maximum position of these peaks, located in the Figure 3.4. Schematic of X-ray diffraction of QDs

to be slightly elongated, particles with the size of 6 ÷ 7
nm. The calculation results give an average size of 6.3
nm.
3.2.2. Absorption and fluorescence spectra
The absorption and fluorescence spectrum of the
sample depends strongly on the grown temperature, as
Figure 3.6. TEM images of
shown in figures 3.7 and 3.8. Observation of absorption
CdTeSe QDs synthesis at 260 oC
spectrum shows that: when the temperature increase,
general tendency, the absorbed band edge is shifted
towards longer wavelengths, from 650 nm to 830 nm when the grown temperature increases from
180 °C to 280 °C. Fluorescence spectra are a wide range where the maximum peak of the emission
band varies depending on the grown temperature, from ~ 630 nm (at 180 °C) to nearly 800 nm (at
280 °C). This emission range corresponds to 1Se - 1Sh exciton emission transition in alloyed CdTeSe
QDs. In general, the grown temperature increases, the maximum peak of the emission band changes
and redshift. The quantum yield of the fabricated samples is presented in Table 3.1.

Figure 3.7. Absorption spectra of QDs
fabricated at temperatures from 180 °C to 280 °C

Figure 3.8. Fluorescence spectra of QDs
fabricated at temperatures from 180 °C to 280 °C


9
Table 3.1. The fluorescent parameters of QD synthesized at different temperatures in ODE-OA media

Sample


30,2
36,1
33,6

3.2.3. Raman scattering spectrum and fluorescence of CdTeSe quantum dots are measured
at temperatures ranging from 300K to 84K
a) Raman scattering spectra measured at different temperatures from 300K to 84K

Figure 3.9. (a) Raman dependence on the temperature of the ternary alloyed CdTeSe QDs. The
insets show the dependence of the frequency of the LO1 and LO2 lines on temperature. (b) A part of the
Raman spectrum in the range of 140 cm-1 to 220 cm-1 is normalized to observe changes in vibration modes
according to temperature.

Raman spectra of CdTeSe QDs at different temperatures, from room temperature 300K to
84K are presented in figure 3.9. The shape of the spectrum does not change when measured from
300K down to 84K. However, the maximum position and the intensity of the spectrum are change.
When the QDs sample temperature decrease, the position of the LO phonon lines is shifted towards
the longer wavenumbers. Specifically, the LO1 (CdTe-like) line displaced about 3.8 cm-1, the LO2
(CdSe-like) line is also displaced by the size of 4.3 cm-1 (figure 3.9b). These results were also
observed by Dzhagan and Mork authors but on CdSe. Explaining the increase in the intensity of the
vibration lines and the position of the vibration peak, when the temperature changes from 300K to
84K, we base on the Morse potential model.
b) Fluorescent spectra recorded at different temperatures from 300K to 84K


10

Figure 3.11 is the fluorescence
spectrum of CdTeSe sample synthesis at
260 oC for 10 minutes measured from 84K

changed (x = 0.2; 0.4; 0.5; 0.6; 08). Diffraction lines for

the composition Te changed (x = 0.2; 0.4;

bulk materials for zb-CdSe and zb-CdSe are also given

0.5; 0.6; 08)


11

We used Raman spectra to evaluate the change in alloy composition (figure 3.14). When the
concentration of Te increases to x = 0.4, the peak characteristic for the LO mode of CdTe is more
clearly observed, this peak intensity increases, the position of CdSe peak observed at the frequency
~ 200 cm-1. When x = 0.5, the intensity of this line increases with the intensity of the same line of the
sample with x = 0.4, but the position of the peak represents the vibration mode of CdSe being shifted
at the frequency188 cm-1. When x = 0.6, the intensity of the two vibration lines is characteristic for
two vibration modes LO CdTe-like and CdSe-like with nearly equal intensity, and locate at frequency
positions 159 cm-1 and 188 cm-1. When the amount of Te increases to x = 0.8, the first peak intensity
at the wavenumber of 159 cm-1 increases sharply. This is the peak that represents the phonon vibration
mode of CdTe-like. This can be explained that the alloy CdTeSe QDs has a difference in lattice
constants (due to crystallization in the zb phase), which leads to the length of the bond be changed
and extended, causing the vibration frequency to be shifted to shorter the wavenumber, compared to
the vibration frequency of CdSe. Moreover, when
the content of Te is small (x ≤ 0.4), CdTeSe tends
to crystallize in the crystalline phase close to CdSe,
but CdSe has a stable crystal phase in a wz
structure, so CdSe-like vibration line located at 200
cm-1. When Te content is large (x ≥ 0.5), CdTeSe
crystallizes with zb structure, so CdSe-like


is the sample with the content x = 0.5 and 0.6 (table 3.2). Besides, the width of the spectrum decreases
when the concentration of Te increases (figure 3.18b).

Figure 3.16. Absorption spectra of CdTexSe1-x
QDs fabricated at 260 oC for 10 minutes with Te content
varying from 0.2 to 0.8

Figure 3.17. Fluorescence spectrum of
CdTexSe1-x QDs (x = 0.2; 0.4; 0.5; 0.6; 0.8) made at 260
o
C for 10 minutes under 532 nm excitation wavelength

Figure 3.18. Dependence of fluorescence maximum position, absorbing edge (a) and FWHM (b) into Te
component of CdTexSe1-x QDs fabricated at 260 oC for 10 minutes

Combining the above results, we found that the fabricated ternary QDs was homogeneous,
zinc-blend (zb) crystalline, with high luminescent efficiency. Samples have good luminescent
performance and locate on the infrared band with x = 0.5 or 0.6 components, suitable for use as a
sensitizer for the solar cell.
Table 3.2. Fluorescence parameters of QDs which Te composition changed

Sample
CdTe0,2Se0,8
CdTe0,4Se0,6
CdTe0,5Se0,5
CdTe0,6Se0,4
CdTe0,8Se0,2

max (nm)

13

also appears 3 diffraction lines, but the position of the two peaks at the larger 2 angles shifted slightly
towards larger 2 values (figure 3.19). This shows that the ZnSe shell may have formed on the core
structure and does not change the core zb-CdTeSe structure. It may also be related to the Se ions
being attracted inside the core during the coating process.

Figure 3.19. Diffraction diagram of CdTeSe core
QDs and CdTeSe/ZnSe core/shell 2ML synthesised at
260 oC (10 minutes). Diffraction lines for bulk materials
for zb-CdSe and zb-CdSe are also given

Figure 3.20. Raman spectra of CdTeSe core QDs and
CdTeSe/ZnSe core/shell have different thickness

When uncovered, the Raman spectrum of the core sample showed only two vibration peaks
at 159 cm-1 and 188 cm-1, similar to prepared those by the Te component of 0.5 in the previous section.
When cover a thin 1ML shell, the spectrum occurs change: the characteristic line for the LO mode of
CdSe changes from 188 cm-1 to 200 cm-1, the intensity of the characteristic line for vibration of CdTe
decreased. Besides, there is a blurred line at 250 cm-1, this is the characteristic line for the LO ZnSe.
The results on the Raman spectra show that the ZnSe shell has been formed but in a small amount.
When the cover is thickened to 2, 4, 6 ML, the characteristic line for CdTe disappears, instead of the
intensity of ZnSe line at 250 cm-1 increases but not much.
The average size
(length) of CdTeSe core
QDs is about 6.3 nm and
increases to 8.3 nm when
covered by the ZnSe 2ML
shell. The shape of the
fabricated QDs is similar

Sample
CdTeSe
CdTeSe/ZnSe 1ML
CdTeSe/ZnSe 2ML
CdTeSe/ZnSe 4ML
CdTeSe/ZnSe 6ML

max (nm)
760
803
842
863
882

FWHM (nm)
116
130
141
153
153

QY (%)
44,9
56,7
28,4
7,7
2,7

3.4.2. The QDs core/shell CdTeSe/ZnTe.
The same as ZnSe shell QDs system, for the

which may be due to the coating process, which has created many electronic traps due to lattice
defects, which reduces the efficiency of electronic-hole recombination and thus reduce the
luminescent performance (table 3.4).
Table 3.4. Fluorescence parameters of core/shell QDs CdTeSe/ZnTe nML (với n =0, 1, 2, 4, 6 ML)

Tên mẫu
CdTeSe
CdTeSe/ZnTe 1ML
CdTeSe/ZnTe 2ML
CdTeSe/ZnTe 4ML
CdTeSe/ZnTe 6ML

max (nm)
763
785
812
829
900

FWHM (nm)
105
114
132
150
160

QY (%)
40,5
18,9
15,6

1 (ns)
2 (ns)

4,9
53,5

CdTeSe/ZnSe
1ML
3,8
47

CdTeSe/ZnSe
2ML
3,1
6,17,6

CdTeSe/ZnSe CdTeSe/ZnSe
4ML
6ML
1,7
2,3
12,7
9,5

The fluorescence decay curve of ZnTe covered CdTeSe QDs with variable thickness given
in figure 3.29. When covering the ZnTe shell, we also observed a decrease in fluorescence intensity
over time, and divided into two segments. At the beginning of time fluorescence decreased very
quickly and after that it decreased slowly and more stable. The results match the experimental curve
with the theory that gives us the results in table 3.6.
Table 3.6. The lifetime of the fitting of the time-resolved fluorescence decay curves in the core CdTeSe

photons are emitted slightly after a laser pulse so that the delay between two photons is roughly a
multiple of 400 ns. The nearly-perfect absence of a peak at zero delays indicates that there is never
emission of two photons following the same laser pulse. This indicates that for these CdTeSe/ZnSe
nanocrystals we have obtained single-photon emission, most likely because multi-exciton emission
is quenched by Auger effect. The minor residual peak might be due to self-luminescence from the
substrate, possibly with a slight contribution from multi-exciton emission.

Figure 3.30. PL intensity autocorrelation function (arb.
units) of a typical individual CdTeSe quantum dot

Figure 3.31. Decay curve (norm.) of the same
quantum dot CdTeSe/ZnSe

Figure 3.31 plots the decay curve of the same quantum dot. This curve is remarkably close to a monoexponential, with an unusually long decay time of 110 ns. This observation, which was reproduced
for all single quantum dots observed with similar 110±15 ns decay times, is in contrast with ensemble
measurements, possibly because the latter is performed at much higher power which could excite


17

multi-excitonic or other nonradiative recombination pathways.
Under the single-QD observation
conditions, there is no (fast) multiexcitonic contribution and, during
the measurement (100 seconds),
there were very few fluctuations of
the decay time. This excellent
Figure 3.32. Intensity–time trace of a typical CdTeSe/ZnSe
stability
is
confirmed

component to measure the parameters.

Figure 3.36. Some pictures of solar cells


18

3.6.1. Effect of distance between two electrodes on the parameters of the solar cell
The J-V characteristic curve of the solar cell has a distance between two electrodes using
sensitizer, which is shown in figure 3.36 and the results of component parameters in Table 3.7.

Figure 3.37. The J-V characteristic curves of solar
cell use QDs as sensitizer with the distance between
the two electrodes changes

Figure 3.38. The J-V characteristic curves of solar
cells using sensitizer are that QDs have Te
components changed

Table 3.7. Typical parameters of solar cells with the distance between the two electrodes changed

Distance

Voc (V)

42 µm
70 µm
110 µm
140 µm



PCE
(%)
0,026
0,036
0,024
0,005

The optimal distance between two electrodes is 70 µm, which corresponds to the highest PCE
and parameters.
3.6.2. Results of measurement of battery parameters when Te component of CdTeSe QDs
changes
Solar cells using sensitizer are the core QDs with Te components changed, the PCE of solar
cells is highest with 0.058% and 0.06% respectively (table 3.8). With the component Te of 0.5, the
fill factor and the open-circuit potential of this sample are quite low compared to a recent publication.
Table 3.8. Typical parameters of solar cells using QDs with Te components changed

Sensitizer
CdTe0,2Se0,8
CdTe0,4Se0,6
CdTe0,5Se0,5
CdTe0,6Se0,4
CdTe0,8Se0,2

Voc
Jsc
(V) (mA/cm2)
0.34
0.11
0.36

43.1

PCE
(%)
0.019
0.021
0.058
0.060
0.035

3.6.3. Light-sensitive solar cells are core/shell QDs
With solar cells use shell QDs types with a layer thickness of 1ML and 2 ML. The parameters
of a solar cell with different shell types and shell thicknesses are listed in table 3.9. The results showed
that the efficiency increased significantly (from 0.056% to 0.185%) when covering ZnSe shell with
a thickness of 1ML, but when the shell thickness increased to 2ML, the efficiency decreased to
0.147%.


19

Figure 3.39. J-V characteristic curves of solar
cells using sensitizer are CdSeTe/ZnSe nML
core/shell QDs with n = 0, 1, 2

Figure 3.40. J-V characteristic curves of solar
cells using sensitizer are CdSeTe/ZnTe nML
core/shell QDs with n = 0, 1, 2

Solar cells using sensitizer are CdTeSe core QDs and CdTeSe/ZnTe 1 and 2 ML core/shells
with PCE not equal to ZnSe cover samples. At the same time, when covering ZnTe shell for cores

0.30
0.21
0.88
0.23
0.64
0.31
0.09
0.25
0.06
0.08
0.05

FF
35.4
47.5
44.4
47.8
47.0
43.3

PCE
(%)
0.056
0.185
0.147
0.027
0.015
0.004

CHAPTER 4.

turmeric are presented in figure 4.4. It can be
seen that Raman spectra of samples in the
spectral region are observed, including many
narrow lines and narrowband groups. All
vibration lines observed in fresh turmeric also
appear in the Raman spectrum of all extracted
curcumin samples (N1 ÷ N5). This proves that
the quality of the fabricated samples is high and
Figure 4.3. Raman spectra of fresh turmeric, natural
of natural origins. Extraction by various
curcumin samples fabricated in this study (N1–N5) and the
methods used in this thesis does not change the
commercial curcumin samples (N8)
structure of curcumin. Raman spectra of the
synthetic curcumin product (N8) and the fabricated samples appear to be nearly identical lines except
for the line at 962 cm-1, 1248 cm-1 and the group of lines at the numbers. longer waves, about more
than 1600 cm-1.
In the spectrum range from 1550 cm-1 to 1650 cm-1, three samples N1, N12, N13 - samples
are extracted from turmeric and sample N6, although they are slightly different at the peak of 1625
cm-1 these four spectra are similar. The location of the vibration lines of these three samples shifts to
about 6 cm-1 toward long wavenumber due to differences in II and III curcumin content in the
compound. For sample N6, the vibration line 959 cm-1 shift to wavenumber about 21 cm-1 long
(Figure 4.5). Samples of N9, N10, and N11 on the market have a completely similar spectrum of N8,
so it can be said that these samples contain only curcumin I without other isomers.

Figure 4.4. (a) Raman spectra comparison of commercial curcumin samples being sold on the Vietnamese
market (N6, N8, N9, N10, N11) and fabricated (N1, N12, N13). (b) and a section of the spectra in the frequency
range from 1550 cm-1 to 1650 cm-1 is zoomed in for easy observation of differences at 959 cm-1 and 1625 cm-1 for
each different sample



1625

 C=C (I,II)Aromatic

1599 1599

1599

1599

1590

1579

1579

 C=O
Phenol C-O (I)

1523 1536
1428

1516
1435

1523

Phenol C-O (II, III)


1599 1599 1600

1599

1536 1531 1533
1428 1429 1427

1183
1166
1148
1118
963

1183
1166
1148
1118
971

1234
1196
1168

1120
976

1226

1183
1166

Cal.

Mangolim 2014

Kolev 2005

Kolev 2005

1626

1630

1601

1615

N10

1632 1625 1626

1248 1248 1247
1236
1229
1226

Cur

1636

Enol C-O ( I)

1168

1149
961

1536
1420

1120
967

1216
1212
1196
1176
1169
1150
1107
966


22

4.3. Study the absorption and fluorescence properties of natural curcumin

Figure 4.5. Absorption spectra of curcumin—ethanol
solutions with different curcumin concentration from 1,
2.5, 5, 10 μg and 20 μg/mL. The inset is a linear relation
of the absorption intensity and curcumin concentration
in this concentration range

4.4. Results of solar cell parameters use curcumin as a light sensitizer

Figure 4.11. J-V characteristic curves of solar cells using sensitizer are is curcumin that varies with
concentration and time of immersion

Table 4.4. Typical parameters of solar cells using sensitizer are curcumin with varying concentrations
and time of immersion

Sensitizer

Voc (V)

Cur 1
Cur 2
Cur 3
Cur 4

0.21
0.28
0.40
0.47

Jsc
(mA/cm2)
0.72
0.92
1.52
1.66

Vmax

published in the Journal of Energy and Power Engineering (6/2017), on the use of curcumin as a
sensitizer in solar cells, this result reached 0.41%. The Korean author, Hee-Je Kim et al in 2013,
published results of lower PCE: 0.36%, and 0.6% when mixed red-cabbage and curcumin at a ratio
of 70:1. Souad AM Al-Bat'hi obtained a PCE of 0.36%. Than Than Win and colleagues, reported on
PCE of 0.129% when using curcumin in 2012, S. Suresh and colleagues also published the results of
PCE of 0.13% in 2015. SJ Yoon et al also published that the solar cell used curcumin reached 0.11%
of PCE. Therefore, it can be said that PCE is low when using curcumin, except for the use of this
natural pigment is environmentally friendly and can meet the needs of individual power use.