American Journal of Applied Science and Technology
9
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VOLUME
Vol.05 Issue 08 2025
PAGE NO.
9-19
10.37547/ajast/Volume05Issue08-02
EXPLORING THE POTENTIAL FOR FABRICATION OF
A FILM-BASED PHOTOTHERMAL CONVERTER
Muhiddin Atajonov Odiljonovich
Department Of Alternative Energy Sources, Andijan State Technical Institute. Andijan, Uzbekistan
Received:
11 June 2025;
Accepted:
26 July 2025;
Published:
08 August 2025
Abstract:
This paper presents the results of a study on the creation of a combined film photothermoelectric
converter from film photo- and thermal converters. The relevance of such research is substantiated. A list of
questions necessary when solving scientific problems in this direction is provided. The importance of selecting
materials and types of converters for obtaining effective hybrid elements is described. The limits of temperature
intervals at which a positive result of experimentation of structures can be expected are shown. The calculation
method and conditions for selecting the initial data for mathematical calculations of the characteristics of the
converters are outlined. The results of the study are presented and the dependence of the electrophysical
properties of the thermoelements and the efficiency of the converters on the temperature of the samples are
analyzed. A conclusion is drawn about the possibility of creating such current sources. The issue of creating highly
efficient solar energy converters has attracted the attention of researchers worldwide on a large scale.
Keywords:
Conversion, photocell, thermoelement, photothermal element, film PV/T Hybrid converters.
INTRODUCTION:
The issue of creating highly efficient solar energy
converters has attracted the attention of researchers
worldwide on a large scale. Many design,
technological and rationalization studies have been
performed in this area. One of the options for
increasing the efficiency of solar converters is to
combine photoelectric converters of solar energy
with a thermoelectric source of electric current [1÷3].
This device justifies itself with a relatively high
conversion efficiency, economic benefit and reduced
heat loss. Another important advantage is the
preservation of fairly good efficiency values of solar
cells, even at high light intensities, by reducing their
operating temperature. The latter is explained by the
strong temperature dependence of the electrical
parameters of semiconductor materials.
It should be noted that photothermoelectric
converters (PTCs) of light and thermal energy, which
are designed to operate under selective lighting
conditions, have provided particularly good results [4-
5]. Of course, to achieve the perfection of the latest
design, it is still necessary to find ways to separate
light radiation for a larger-area PTC. The results
obtained by selective lighting solar cells will not
match the results of large solar power plants. This is
attributed the problem of separating light flux from
solar radiation for large-area converters. Young
researchers are currently working on this topic.
Another problem with PТС is its weight and
dimensions. The presence of a thermoelectric
generator of a volumetric design makes it, to some
extent, rough and inconvenient to operate.
Therefore, this work examines the possibility of
creating film photothermal converters.
FORMULATION OF THE PROBLEM
The task of minimizing the overall dimensions of
energy converters and providing a positive solution to
the issue of weight and economic indicators of solar
and thermoelectric sources of electrical energy
certainly require a transition to film structures of such
units. Until, recently film thermal converters, have
been used as sensors and measuring elements in
instrumentation, electronics and many other
industries [6÷8]. The widespread use of film
photoelectric and thermoelectric converters in
practice began to develop with the transition to
micro- and nanoelectronics. However, limiting
ourselves to this population does not demonstrate all
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
the possibilities of these alternative energy sources.
The population's need for electricity poses the task of
finding new types and designs of converters that can
operate with fairly good economic and energy
efficiency. Unfortunately, many factors prevent the
creation of such devices, requiring scientists and
engineers to find solutions to these obstacles. For
example, the strong temperature dependence of the
electrophysical
parameters
of
semiconductor
materials prevents solar cells from operating with
concentrated light radiation, complex and expensive
manufacturing technology prevents them from being
widely used, and their fragility and large geometric
dimensions reduce service time. For thermoelectric
converters, their volumetric structures require a large
amount of raw material and create difficulties for
transportable movements; additionally, the low
efficiency factor (efficiency) does not satisfy the
needs of consumers of electrical energy. Therefore,
to compensate for one device, the second device
should be advantageous because it ultimately leads
to a combination of converters. One of the products
of such a solution is a device developed for converting
light
and
thermal
energy
into
electrical-
photothermoelectric converters (PTCs) [3]. To date,
several modifications of the PTC have been created
[3÷5]. Among them, photothermal elements
designed to operate under selective lighting
conditions have the highest efficiency. It should be
noted that for this design to be able to widely enter
the consumer market, additional problems still need
to be solved related to the configuration of energy
converters with an optical set that serves to distribute
light radiation into different spectra. In addition, it is
necessary to identify the conditions for using such a
converter for medium and high-power consumers.
These questions remain open. Deciding on weight
and dimensions is also important. The results of
obtaining the scope in the area of use are highly
dependent on this problem. Solving this problem
leads to savings in terms of raw materials, and
accessibility, reducing the problems of moving
devices from one place to another and the possibility
of serially producing such energy sources in large
quantities [7].
The development of PTCs based on film solar cells and
thermoelectric converters may perhaps be one of the
works that could respond positively to the task set. An
analysis of domestic and foreign literature shows the
lack of sufficiently illuminated work in this regard. To
date, there has been one work [9], in which a
thermoelectric converter was used as a low-power
electricity generator and a cooling device for a film
photocell. This combination of converters was
created based on the Peltier effect [10,11]. In
comparison, the most interesting solution is to create
a combined film PTC that operates on the basis of the
Seebeck effect [12,13].
THIS IS EXPLAINED AS FOLLOWS
Despite the lack of a forecast for the efficiency of the
planned design of a film photothermal converter, the
development of this source has made it possible to
obtain a certain gain in economic efficiency. The
device
becomes
compact,
lightweight
and
transportable. It is widely used in hard-to-reach areas
of the planet. It is an autonomous source of direct
current. In any case, under equal operating
conditions, the efficiency of the device is greater than
the efficiency of photoelectric conversion. By varying
the parallel and serial connections of the photo and
thermocouples of the converters, the operating
current and voltage of the device can be adjusted. In
summary, the beginning of research in the direction
of creating a film photothermal converter, in our
opinion, is promising to some extent.
Based on the above reasoning, the objectives of this
research are to analyze and select the designs, types
and
materials
of
film
photoelectric
and
thermoelectric converters of light and thermal
energy; develop technology for manufacturing film
PTCs; identify their operating conditions; conduct
experimental studies; measure and determine the
operational characteristics of the device under
laboratory and field conditions; determine the
configuration of the converter; solve the issue of
cooling the cold junctions of the thermoelectric part
of the unit; and perform a theoretical calculation of
parameters using modeling with modern software.
Note that creating the planned design and studying it
within a wide range of light intensities and operating
temperature differences may require the creation of
additional experimental installations. The work plan
includes provisions for the possibility of working in
created installations with various types of
measurements, for example, with concentrated
radiation.
Analysis and Selection of Film Type Film Solar Cells
for PTCs
Considering that the choice of a film photoelectric
converter is made with the aim of creating a photo
thermoelectric converter that is convenient to use
and has good weight and size characteristics, we carry
out a comparative analysis of technologies, materials,
cost and efficiency of thin-film solar cells. These
materials have the best qualities in terms of flexibility.
There are several types of inorganic film converters of
light energy into electrical energy: films made on the
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
basis of amorphous silicon (a-Si), cadmium telluride
films (CdTe) and film solar cells made of copper-
indium and gallium selenide (CuInGaSe2) Of course,
depending on the electrophysical parameters and
manufacturing technology, the efficiency ranges from
10% to 22%. For example, the efficiency of
photoconverters manufactured by First Solar from
amorphous silicon is approximately 10÷11%. The
Japanese company Solar Frontier produces solar cells
based on copper, indium and gallium selenide
materials with efficiency. 12÷13%. In contrast to
these samples, commercially produced solar cells
made of cadmium telluride (Mia Soli modules) are
efficiency. 15.7%. in 2016, solar cells with the highest
conversion coefficients based on CuInGaSe2 (EMPA)
produced products with efficiency. 18.7%. the
laboratory samples of the listed elements exhibited
values an order of magnitude greater, that is, greater
efficiency. Individual thin-film solar cells; and
laboratory samples of elements made of amorphous
silicon - 12.2% (United Solar), CdTe - 17.3%; (First
Solar), and CIGS - 20.5%; (ZSW) were used.
Note that today there are solar film batteries with
significantly higher efficiency indicators. Table №1
shows
the
energy
and
weight-dimensional
characteristics of the flexible solar panels of the
KIBOR panel.
Table No. 1 [14]. Thin-film flexible solar panels KIBOR.
As shown in Table №1, on average, solar panels can
be efficiently constructed.
⁓
20%. In [3], it was clearly
formulated that to create a photothermal converter
capable of compensating for a decrease in the
efficiency of the photoelectric converter with
increasing temperature and having the highest
conversion coefficient values, it is important to select
a sample with the best efficiency values. and
temperature coefficient, we will focus on solar
converters with an indicator of this parameter of at
Panel power
(W)
Size
(mm)
Efficiency
%
I mp (А)
Vmp
(V)
Isc
(А)
Voc
(V)
Weight,
(kg)
18 W
277*434*3 mm
20.5 %
0,92 А
19,3 V
1,04 А
23,6 V
0,29
25 W
277*555*3 mm
21.5 %
1,43 А
17,5 V
1,55 А
21,5 V
0,57
30 W
375*535*3 mm
19.6 %
1,72 А
17,4 V
1,93 А
21,3 V
0,75
40 W
415*535*3 mm
22.2 %
2,34 А
19,4 V
2,06 А
23,5 V
0,90
50 W
535*555*3 mm
21.5 %
2,85 А
17,5 V
3,06 А
21,5 V
1,0
60 W
535*734*3 mm
19.6 %
3,44 А
17,4 V
3,71 А
21,11 V
1,46
75 W
535*820*3 mm
21.1 %
3,81 А
19,3 V
4,11 А
23,93 V
1,65
80 W
540*922*3 mm
18.8 %
5,20 А
15,3 V
5,62 А
18,79 V
1,85
85 W
550*1050*3 mm
18.6 %
5,06 А
16,8 V
5,61 А
20.19 V
2,10
90 W
540*1050*3 mm
19.0 %
5,27 А
17,0 V
5,71 А
20,69 V
2,00
95 W
540*1050*3 mm
20.2 %
5,47 А
17,3 V
5,90 А
20,89 V
2,00
100 W
540*1050*3 mm
21.3 %
5.71 А
17,6 V
6,07 А
21,69 V
2,00
110 W
540*1175*3 mm
20.5 %
5,64 А
19,54 V
6,03 А
23,49 V
2,25
120 W
540*1305*3 mm
20.5 %
5,44 А
22,09 V
5,86 А
26,49 V
2,45
130 W
540*1435*3 mm
19.5 %
5,43 А
24,09 V
5,96 А
29,00 V
2,60
135 W
540*1435*3 mm
20.8 %
5,61 А
24,19 V
6,04 А
29,29 V
2,60
140 W
796*1082*3 mm
19.5 %
7,08 А
19,79 V
7,78 А
24,98 V
2,68
150 W
796*1082*3 mm
21.3 %
7,51 А
20,01 V
8,11 А
24,49 V
2,68
180 W-1
796*1305*3 mm
20.0 %
5,49 А
32,91 V
5,86 А
39,79 V
3,0
180 W-2
796*1305*3 mm
20.0 %
10,72А
16,79 V
11,58А
20,29 V
3,0
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
least 20%. This is a good indicator, even compared to
the crystalline solar panels currently used. Thus, a
study of the modern market has shown that samples
from cadmium telluride and indium-copper-gallium
sulfide are recommended for creating a combined
photothermal converter. By 2020, despite the
continued production of rigid variants, cadmium
telluride solar cells had become the most common
modification of the flexible battery market. This
connection benefits from its low cost and high
efficiency, even under nonideal lighting conditions.
The efficiency of serial products made from these
materials reaches 20-22% [15]. An important
parameter is that the temperature coefficient for
such samples is 2-3 times lower than that for
monocrystalline and polycrystalline silicon.
Among the flexible panels under consideration, today
we
consider
indium-copper-gallium
sulfide
CuInGaSe2 to be the most effective. However, they
have a high manufacturing cost. Currently, they are
practically not used on earth. Due to the high cost,
only spacecraft are equipped with this type of
photovoltaic energy. The efficiency of the best
samples of these elements reaches 35-40% or higher
[16]. The produced samples are extremely reliable
and minimally degradable even under extreme
conditions at extremely low and high temperatures.
However, there is a third generation of thin films
based on polymers, organics and quantum dots.
However, for now, we are neglecting them due to the
relatively low efficiency values: 14-17%. Despite this,
in the future it may be necessary to pay serious
attention to the following advantages: general
availability and cheap production, maximum
functionality, environmental safety and the ability to
make films almost transparent [17]. Perovskite
elements are a continuation of third-generation
elements. However, these elements are not suitable
for our purposes. The latter is explained by the short
service life, which lasts only 1.5-2 years.
The question of which substrate (glass, plastic or
metal) should be used in a thin-film light-to-electric
converter will be decided upon later. The use of these
devices depends on the switching materials; and the
soldering and connection technology of the
photoelectric converter to the TEG. Analysis and
accounting of the toxicity of starting materials can
also be considered not yet part of our task. This is
explained by the creation of a hybrid PTC converter
based on ready-made components; that is, we obtain
the PV and TEC in finished form.
Selecting a Film Thermal Converter
Compared to that of solar cells, the transition from
bulk thermoelectric generators to thin film
generators is an important factor. This procedure
justifies itself primarily by solving the problem
associated with the weight and size characteristics.
The significant impact of the transition is also
reflected in the savings in raw materials from which
thermoelements are made.
The development of technology for producing
thermopiles by microminiaturization has achieved
noticeable progress in recent years. Their dimensions
today are at the millimeter level. The length of the
branches of thermoelements was reduced by more
than ten times, that is, to 0.15-0.2 mm [18]. Currently,
experts in this field know that thermoelements,
unlike bulk thermoelements, are manufactured by
thin-film deposition in various ways on an electrical
and thermal insulating substrate. This can be
achieved by vacuum deposition, solution deposition,
metal-organic chemical vapor deposition (MOCVD),
and molecular beam epitaxy (MBE). In general, a
module is manufactured by applying thin films and
creating patch plates in the form of a pattern.
The choice of a film thermal converter should take
into account not only its advantages, but also its
disadvantages compared to volumetric thermal
converters. In [18], by comparing the characteristics
of two types thermal converters (bulk and thin-film),
it was concluded that thin-film TECs have an
advantage
in
terms
of
the
generated
thermoelectromotive force (thermo-EMF).
𝑌 = 2𝑁𝑆
(1)
𝐸 = 𝛼
2𝑁
𝑆
𝑆∆𝑇 = 𝛼𝑌 ∗ 𝑆∆𝑇,
(2)
𝐸
𝑏
𝐸
𝑇.𝑓
=
𝛼
𝑏
𝛼
𝑇.𝑓
∗
𝑌
𝑏
𝑌
𝑇.𝑓
≈ 1,5 ∗ (0,05 … 0,1) ≈
0,08 … .0,15
(3)
where Y is the packing density of the TE, and 2 N
thermoelements; ET.f and Eb are, the thermopowers
of thin-film and bulk TECs, respectively; and S is the
surface area of the TE.
This large value of the thermoelectromotive force
(EMF) makes further use of the converted energy
easier. It is also shown that with a correct comparison
of the generated thermo-EMF relative to the heat
flux, the efficiency of volumetric TEGs is noticeably
greater both in terms of generated power and
conversion efficiency. In addition, volumetric TEGs
have advantages in terms of efficiency. noticeably
compared to thin-film generators. The disadvantages
of the latter include the low efficiency of the
semiconductor thermoelectric material and high
resistance. The first drawback fundamentally limits
converter manufacturing technologies. The second
disadvantage is the cost of miniaturization and high-
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
density packaging of thermoelements. For the
application of electricity generation with a thin film
converter, it may be promising to search, among
other new thermoelectric materials, for more
efficient hybrid structures, in particular those with
photovoltaic devices.
The design of the combined-film photothermal
generator we propose is shown in Figure 1. However,
the creation of such a hybrid design is also not
without the importance of solving several issues
related to switching, flexibility, and the complexity of
the collection technology and determining the scope
of their application. Therefore, Figure - 1a shows a
general top view of a film photothermal converter.
The area of the photoconverter must be equal to the
area of the free area on the side of the TEC hot
switching plates. The light energy arriving at the
surface of photovoltaic converters (PVCs) is not
converted into electrical energy. Most of the light,
turning into heat, should arrive at the hot junctions of
the
TEC.
Therefore,
a
serial
connection
thermoelement (TE) is placed around the perimeter
of the solar cell.
Fig.1. Top and side views of a film photothermal converter.
The design is designed for separate loads. However, if
the geometric dimensions and number of TECs are
selected, methods of connecting them in parallel or in
series, you can include them in the total load. For this
purpose, a TEC must be manufactured on a film with
a rectangular shape and a free area in the middle
equal to the photoactive surface of the
photoconverter. Since the industry does not yet have
such a TEC design, it will be necessary to resolve this
issue. In the literature [19], there are film
thermoelements with a round configuration (Fig. 2).
Since the industry produces round-shaped solar cells,
we think it is possible to select such a system for
combining two generators. The sample was made of
silver selenide.
Fig.2. The arrangement of the film fuel cells is circular
CALCULATION
METHOD
FOR
THE
FILM
PHOTHERMAL CONVERTER
In principle, we can assume that in this case it is also
possible to use the method of calculating the PVC of
a volumetric structure [20]. Heat is supplied to the hot
junctions of the TEC through the electrically insulating
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
layer from the photoelectric converter. Here we
should note another problem associated with the
selection of an electrically insulating, but well-
thermal-conducting layer material between the hot
junction of the TEC and the PVC. We will leave this
task for the experimental part of the work. In this
case, the proximity of the coefficients of thermal
expansion of the layer materials, hot switching plates
and rear contact of the solar cell should be
considered. Solving this issue also requires
determining the flexibility of the material. At low light
intensities, this difference may not be significant.
However, the use of this design with concentrated
radiation becomes important. Using [20] will not
require any corrections to the formulas. The reflective
layer allows thermal energy to be transferred from
the solar cell to the hot junctions of the TEC without
loss.
Because the photovoltaic and thermoelectric parts
are connected to different loads, the following
formulas can be used to calculate the efficiency of
converters
𝜂
𝑃𝑉𝐶
=
Р
𝑝𝑣𝑐
𝑚𝑎𝑥
Р
𝑖𝑛𝑐
(4)
𝜂
𝑇𝐸𝐶
=
Т
ℎ
−Т
𝑐
Т
ℎ
∗
М−1
М+
Т𝑐
Тℎ
(5)
In the above formulas Р_PV^max and Р_inc
- are the
powers released at the PV load and incident on the
front surface of the solar cell, respectively; Th and Tc-
are the temperatures of the hot and cold junctions of
the thermoelement branches, respectively.
М = √1 + 𝑍
𝑎𝑣
Т
𝑎𝑣
.
After these values, are determined the efficiency of
the hybrid unit
𝜂
𝑃𝑇𝐶
= 𝜂
𝑃𝑉𝐶
+ 𝜂
𝑇𝐸𝐶
(1 − 𝜂
𝑃𝑉𝐶
)
(6)
Using formula (2.34), proposed by A.F. Ioffe, the
values of Peltier and Joule heat cane be considered. It
is well known that formula (2.34) includes the
parameter Z, which is called the thermoelectric figure
of merit, and the higher this indicator is, the greater
the efficiency value. transformations. To carry out
computational studies, substances with the best
thermoelectric properties were taken. These
temperatures corresponded to room temperature
and their temperature dependence was taken into
account. Conditions were set for the temperatures of
the photoelectric converter and the hot junctions of
the TEC to be identical. In the calculations,
temperature values were specified to be significantly
lower than room temperature, that is, down to -80°C
toward cold temperatures.
Parameter M is equal to the optimal ratio of the load
resistance of TEG. Based on the fact that Т_av is found
from the absolute values of the temperature of the
hot and cold junctions of the thermoelement
branches, it is possible to calculate the average
integral thermoelectric figure of merit of the material
for the selected temperature range and both
branches of the thermoelectric element
Т
𝑎𝑣
=
Т
ℎ
−Т
𝑐
2
(7)
𝑍 =
1
2
(𝑍
𝑎𝑣
𝑛
+ 𝑍
𝑎𝑣
р
).
(8)
In (8), the parameters
𝑍
𝑎𝑣
𝑛
and
𝑍
𝑎𝑣
р
were
calculated from the relations
𝑍
𝑎𝑣
𝑛
=
1
Т
ℎ
−Т
𝑐
∫
𝛼
𝑛
2
(Т)𝑑𝑇
𝜒
𝑛
(𝑇)𝜌
𝑛
(𝑇)
Т
ℎ
Т
𝑐
, and
𝑍
𝑎𝑣
𝑝
=
1
Т
ℎ
−Т
𝑐
∫
𝛼
р
2
(Т)𝑑𝑇
𝜒
р
(𝑇)𝜌
𝑝
(𝑇)
Т
ℎ
Т
𝑐
.
where
𝛼
𝑛
(Т), 𝛼
𝑝
(Т), 𝜒
𝑛
(Т), 𝜒
𝑝
(Т), 𝜌
𝑛
(Т), 𝜌
𝑝
are,
the values of the coefficient of thermal field, the
thermal conductivity and the resistivity of the p-n
branches, respectively.
Note that the thermoelectric efficiency of p-
and n-branch materials can be calculated
graphically. Graphical calculation of the Z
parameter is carried out by integrating the known
temperature
dependencies
𝑍
𝑛
=
𝑍
𝑛
(Т) 𝑎𝑛𝑑 𝑍
𝑝
= 𝑍
𝑝
(Т).
However, taking into
account that numerous calculations give almost
identical results, that is,
𝑍
𝑎𝑣
𝑛
and
𝑍
𝑎𝑣
р
are close, the
expression
𝑍 =
𝑍
𝑎𝑣
𝑛
+𝑍
𝑎𝑣
𝑝
2
.
(9)
The main purpose of this theoretical study was to
consider the temperature dependence of the
thermoelement efficiency, taking into account the
temperature dependence of the electrophysical
parameters of the thermoelectric semiconductor
material α, ρ, and χ. Therefore, the parameters of the
real substance were chosen among materials in the
low-temperature region. This was based on the
assumption that the operating temperature range of
the film photothermal converter is from -80°C to
120°C. A temperature of 120°C on the surface of the
photoconverter, and, consequently, on the hot
junctions of the thermoelement, can be obtained
with concentrated radiation of approximately twenty
times the amount of sunlight [3]. Thus, it was possible
to use increased light intensity incident on the front
surface of the solar cell.
The thermal resistance, internal resistance and
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
optimal current at the thermopile load were
calculated using the following formulas:
Е
𝑇𝐸𝐶
= 𝑛(𝛼
𝑛
′
− 𝛼
𝑝
′
)(𝑇
ℎ
− Т
𝑐
)
(10)
𝑟
𝑖𝑛𝑡
= 𝑛(𝜌
𝑛
′
+ 𝜌
𝑝
′
)
𝑙
𝑠
(11)
𝐼
𝑙.𝑜𝑝𝑡
=
Е
𝑚+1
,
(12)
where
𝑚 =
𝑅
𝑟
𝑖𝑛𝑡
= √1 + 𝑍
𝑎𝑣
Т
𝑎𝑣.
Here,
𝛼
′
=
1
𝑇
ℎ
−Т
𝑐
∫ 𝛼(𝑇)𝑑𝑇;
Т
𝑐
Т
ℎ
𝜌
′
=
1
Т
ℎ
−Т
𝑐
∫ 𝛼(𝑇)𝑑𝑇;
Т
𝑐
Т
ℎ
n is the number of thermoelements in the TEG.
The heat flow from the back of the
photoelectric converter to the hot junctions of the
TEC is:
𝑄 = 𝑄
χ
+ 𝑄
п
(13)
where
𝑄
χ
and
𝑄
п
are the heat flows leaving the hot
junctions due to the thermal conductivity of the
branches and the Peltier effect, respectively.
Note that due to the insignificant values of heat flows
arising from the Thomson and Peltier effects, they can
be neglected. Due to the weak temperature
dependence of the thermal conductivity of the
material, these heat flows are linearly distributed
along the branches of the fuel cell. This justifies the
method of averaging adopted when calculating the
internal resistance of the TEC and the heat flow due
to the thermal conductivity of the branches Q_χ by
integration over temperature, together with
integration over the length of the branches. If taken
into account, they can be determined using the Ioffe
formula [21].
Thus, the useful power released at the load of the
thermoelectric converter
𝑃
𝑇𝐸𝐶
𝑢𝑠
= 𝐼
2
𝑅 = 𝐼
2
𝑟
𝑖𝑛𝑡
𝑀.
(14)
The efficiency of the thermoelectric part of
the photothermal converter is calculated
according to
𝜂
𝑇𝐸𝐶
=
Р
𝑇𝐸𝐶
𝑢𝑠
𝑄
п
+𝑄
𝜒
.
(15)
RESULTS AND DISCUSSION
Based on the calculation results, the temperature
dependence of the useful power of the photoelectric
converter, thermal converter and photothermal
converter was obtained. Figures 3-5 show the results
of studying the electrophysical parameters of the
branches of a film thermopile.
Fig. 3. Temperature dependence of the resistivity of the TE branches.
Fig. 4. Temperature dependence thermal conductivity of the TE branches.
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Fig. 5. Temperature dependence of the thermoelectromotive force coefficient of fuel cell branches.
As show in Figure 3, the resistivity of the electronic
conductivity branch increases monotonically with
increasing temperature. For the positive branch, this
parameter first increases slowly up to a value of 375
K, after which the growth accelerates. From this we
can conclude that the electrical conductivity of the n-
type conductor decreases faster than that of the p-
type conductor. There is a noticeable difference in the
temperature
dependences
of
the
thermal
conductivity of the TE branches (Fig. 4). In this case,
the thermal conductivity of the electronic
conductivity branch up to 375 K remains practically
unchanged. In addition, the thermal conductivity is
significantly less than that of the p-type alloy. This
phenomenon to some extent compensates for the
decrease in electrical conductivity, which contributes
to an increase in the value of TE efficiency. In
addition, thermal emf. The n-branch first increases
with increasing temperature, and then decreases (Fig.
5). In contrast to that of the n-branch, the coefficient
of thermoelectromotive force of the positive branch
first decreases, and after reaching a temperature of
aapproximately 450 K, it grows strongly.
A comparison of the research results with the results
of previous works [22÷25] showed that our results
maintain an intermediate limit between the data
given in these studies.
Figure 6 shows the efficiency dependence. Photo,
thermal and photothermal converters from
temperature, as a result of processing the received
data. Based on the results of a computational and
theoretical study, it was established that the
efficiency of a film photocell decreases with
increasing temperature in the same way as that of
plate solar converters. The pattern of decrease in
sample productivity is similar to that of the second
type, that is, the plate type. The efficiency of the
thermal converter increases monotonically. The value
of the payload on the external circuit of the TEC is
relatively low in volume. This can possibly be
explained by the geometric dimensions of the film
thermoelements.
However,
reducing
the
temperature of the cold junction of the
thermoelement traditionally leads to an increase in
the efficiency of the converter, which confirms the
presence of the Seebeck effect. Overall, the efficiency
of the hybrid film photothermal converter allows us
to conclude that it is logical to create a film PTC.
[26÷27].
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
Fig.6. Dependence of the efficiency of thermo (1), photo (1a, 2a, 3a) and photothermal batteries (1b, 2b, 3b)
batteries on temperatu
re at ТC=0оС (a).
Fig.6. Dependence of the efficiency of thermo (1), photo (1a, 2a, 3a) and photothermal batteries (1b, 2b, 3b)
batteries on temperature at ТC=
-
80оС (b).
For their manufacturing technology, we can say the
following. Unlike in the installation of volumetric
PTCs, the manufacture of film combined elements
does not require the selection of special chemicals
because of the compatibility of the soldered parts of
the ceramic plate, photoconverter or thermal
converter, as was shown in [3]. In this case, they can
be constructed by spraying or gluing. Only here is it
also important to correctly select the sequence of
spraying with the appropriate substance. [28,29].
CONCLUSION
The conducted research shows that ways of finding
economic and design solutions for weight, size and
technical and economic indicators, a method of
creating film combined converters based on film
photoelectric and thermoelectric current sources, is
encouraging for obtaining positive results from
experimental studies of such structures. The creation
of a proposed current source contributes to the
transition to hybrid generators with fairly good
efficiency values. and, perhaps, obtain tangible
productivity when using secondary resources of heat
sources.
Weight,
size
and
transportability
characteristics are undoubtedly improving. Savings
are achieved in the consumption of raw materials.
When solving the issue related to finding flexible,
well-heat-conducting and electrically insulating
materials, their use becomes more convenient.
ACKNOWLEDGMENTS
The study was very helpful with the ideas of my
supervisor Anarxan Kasimaxunova. I express my
gratitude to her.
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
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