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CHEMICAL ENGINEERING TRANSACTIONS

VOL. 46, 2015

A publication of

The Italian Association

of Chemical Engineering
Online at www.aidic.it/cet

Guest Editors: Peiyu Ren, Yancang Li, Huiping Song
Copyright © 2015, AIDIC Servizi S.r.l.,
ISBN 978-88-95608-37-2; ISSN 2283-9216

Application of a Different Morphology of Inorganic Compound
in the New Energy Generation

Xuan Gong*, Gouli Li

School of electrical engineering and automation, Anhui University, Hefei, 230039, Anhui province, China
gongxuan19831117@163.com

New energy is also known as non-conventional energy. Part of the renewable energy utilization technology
has made considerable development, and play an important role around the world. The technology of
biomass, solar, wind, hydroelectric power, geothermal energy and so on has been widely applied. For each
forms energy, the morphology of the materials is quite important. Based on the overview of existing published
papers, the compound can be used to improve the efficiency of the new energy power generation due to its
complex nature. In addition, the performance of the material will change when the size is small enough.
Therefore, both the two advantages can be used in the efficiency improving in the new energy field. In the
paper, a new method to improve the performance of the new energy generation efficiency has been proposed
with compound morphology. According to the experimental results and analysis, the method can be used in
the performance improving in the new energy field. The results show the validity of the method and it can also
be used in other fields to improve performance.

1. Introduction

New energy is also known as non-conventional energy. It refers to the variety forms of energy outside
traditional energy sources, which including solar (Novacheck and Johnson (2015), Zirnhelt and Richman,
(2015)), geothermal energy (Stauffacher, Muggli, Scolobig, et al, (2015)), wind energy (Ritter, Shen, Cabrera,
(2015)), ( Bilir, Imir, Devrim, et al, (2015)), ocean energy (Rusu and Onea (2016)), biomass and nuclear fusion
energy (Ryzhkov (2015)), etc. Part of the renewable energy utilization technology has made considerable
development, and play an important role around the world. The technology of biomass, solar, wind,
hydroelectric power, geothermal energy and so on has been widely applied. In variety forms of the new
energy, solar cell is an important way to generate the power.
The solar cell (Khezami, Megbel, Jemai, et al, (2015)), which is based on the photoelectric effect, is a main
method to converting the light energy to electrical power. There are two kinds of the solar cell: organic type
and inorganic type. In actual application, the research work often combines the advantages of the two types
semiconductors.
For both of the two kinds of solar cell, the structure of the materials is quite important to affect the
performance. For the inorganic materials, both pure substances and compound are discovered as the material
in the solar cell (Han, Leo, Kim, etal (2014)). The various elements are from the third main group and fifth
main group in the periodic table of the elements. For the organic materials, the research on the compound of
inorganic crystals quantum dots and organic semiconductor has been greatly developed (Lee, Issam, Belmahi
(2009), Beecher, Yang, Palmer (2014)). Organic semiconductors can be divided into three classes: organic,
polymer and a donor acceptor complexes (Kollender, Gasiorowski, Sariciftci, (2014), Umeyama, Imahori,
(2014), Patil Hemlata(2014)). For both types of semiconductor materials, the application is often appeared in
the form of compound.
Based on the existing research work, the compound materials are usually adopted to improve the
performance of solar cell. Meanwhile, the size scale is also becomes a hot point to study. When the material is
in quantum level, the performance will be greatly changed, which can be used to help improving the
performance of the solar cell. For various compounds, PbS is a semiconductor compound in IV -VI columns in

DOI: 10.3303/CET1546161

Please cite this article as: Gong X., Li G.L., 2015, Application of a different morphology of inorganic compound in the new energy generation,
Chemical Engineering Transactions, 46, 961-966 DOI:10.3303/CET1546161

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the element periodic table (Reich, Chen T, Efros, (2013)). Its characteristics of narrow band gap and larger
exciton Bohr radius are quite useful to improve the efficiency of the solar cell.
For the preparation of the solar cell, the preparation of the PbS quantum dots is quite important. For the
industry use, the cost of the preparation process should be cheap, and the production should has great
performance. In order to improve the performance of the new energy power generation efficiency, a
compound of PbS quantum dots has been prepared to improve the performance of the solar cell.

2. PbS quantum dot preparation

PbS is a semiconductor compound in IV-VI columns in the element periodic table (Yanyan Gao(2012)). It has
the narrower band gap and larger exciton Bohr radius. This material has potential applications in light -emitting
diodes, single electron transistor, field effect transistors, solar cells and thermoelectric materials.
Compared with physical method, quantum dots detector prepared by chemical solution can combine the
advantages of high performance and low cost (Kovalenko Maksym V(2010), Shiohara Amane(2010), Morris-
Cohen Adam J(2010), Kachoosangi Roohollah Torabi(2008),and Chatteriee Dev K(2008)). It can control the
quantum dot size according to the amount of solvent, reaction temperature, reaction time and other
parameters to adjust the material band effectively.
In recent years, there has been a lot of reports for the synthesis of PbS quantum dots with different
morphology by variety of methods (,Khiew PS (2003), Sun Bing(2013), Zhou GJ(2006), Zhongbiao
Zhao(2013)): PbS nanocrystals with square shape are prepared by the unit precursor decomposition and
solution backflow; PbS nano crystal is prepared through the combination of the surface active agent and a
polymer substrate; PbS nanowires and nanoplates can be obtained through polymer assisted thermal metho d;
Multi legged PbS nano crystal rod can be obtained according to the thermal decomposition of molecular
precursor; through the method of aqueous phase, nanocrystalline PbS with eight symmetrical arms along the
111 surface has already been prepared; dendritic PbS nanocrystals, as a kind of interesting supramolecular
structure has the potential applications due to its special morphology and properties.
Direct PbS preparation method has been used in the research work. Preparation of precursor of benzoic acid
lead is prepared according to the method in the reference (Zhang, Lee, Vittal, et al), (2006)], which is modified.
In this paper, benzoic acid and lead acetate were dissolved in anhydrous alcohol, and the concentrations of
the two reactants were diluted. A magnetic force mixer was used to stir the lead acetate solution, and then a
loop mixer was inserted into the liquid level of lead acetate solution to leak the benzoic acid when it was
stirring. The whole process will be realized at the condition of 55 ℃. The loop mixer is shown in Figure.1.

Figure 1: Schematic view of mixing process of benzoic acid and lead acetate

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The synthesis of PbS quantum dots is based on the PbS quantum dot technology proposed by Zhang (Zhang,
Lee, Vittal, et al, (2006)). The PbS quantum dot is obtained by improving its method. Under the condition of 60
℃ and slow stirring speed, the morphology of PbS quantun dots are controlled by adjusting the physical
conditions of the reaction, such as introducing reaction solvent and reaction additive, controlling reaction time,
and so on. The reaction solvent is to make the reaction in liquid phase, and slow mixing can help to make the
reaction more uniform. In the process of the experiment, the temperature of the reaction solution and the
rotating speed of the circulation agitator are especially controlled.
The X ray diffraction analysis result of Pbs quantum dots shows the diffraction peaks at 26.10, 29.90, 43,
50.70, 62.90, 53.20, 71.1 and 79. Compared with the standard card, the corresponding growth orientation was
(111), (200), (220), (311), (222), (400), (420) and (422). It can be proved that the PbS quantum dots are
obtained. Average diameter of the quantum dots can be calculated by the Debye-Scherer equation according
to the average diffraction peak of half peak width:





cos

a
D 

Where, D is the average diameter of the quantum dots; a is the geometrical factor, a=1.0;  is the

wavelength of X ray, and its value is 1.54178;  is the half peak width;  is the diffraction angle. Then, the
average diameter of the quantum dots obtained is 5.1nm.

3. The preparation of the solar cell

From the viewpoint of thermodynamics, it is easy to inject the photoelectron of the quantum dot to the
conduction band level of nanocrystalline thin film SnO2, which makes the photoelectric conversion
performance of PbS quantum dot sensitized SnO2 nanocrystalline thin film solar cell much better. In this
paper, SnO2 nanocrystalline thin film was sensitized by PbS quantum dot to improve the photoelectric
conversion performance.
In these steps, SnO2 colloid will be prepared as following steps:
1) The SnO2 nano powder (35-50nm) was applied to the ultrasonic apparatus, and the container of the
ultrasonic instrument was closed after injecting certain amount of acetone solution. The SnO2 solution can be
obtained after 2.5h with the ultrasonic and stirring action.
2) In the process of volatilizing of the acetone, the SnO2 colloid will become viscous. In the mixing process,
some Triton (TritonX-100, the composition of C34H62O) should be added by a certain amount. The SnO2
colloid obtained will be coated on the FTO conductive glass.
3) In the high temperature environment of 550℃, 45min is needed to provide. Then, SnO2 was sintered in
different constant temperature environments, and the porous film was obtained.
The battery assembly process is listed as the following:
1) PbS quantum dot solution was prepared when it is soluted in a certain amount of 20mL toluene. The
solution is dark. The FTO coated with SnO2 film was prepared by drying 30min to remove the moisture content
in the porous.
2) The production of step 1 will be placed in the MPA and acetonitrile mixed solution, whe re the percentage of
the MPA 20%.
3) Connect the SnO2 nanocrystalline thin films to the carboxyl group at one end of MPA.
4) Connect the PbS quantum dot sensitized agent and the molecular connector.
5) After 48h of immersion, the PbS sensitized SnO2 nanocrystalline thin film was taken out. It can be seen that
the positive and negative sides of the glass are both become dark, which means that the PbS quantum dots
have been chemically adsorbed on SnO2 nanocrystalline films.
Then, SnO2 sensitized by the quantum dot should be washed several times by alcohol. When the film was
dried, it can be used to test the performance.

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electrolyte
PbS

SnO2

FTO

Figure 2: Assembly of the solar battery

4. Experiment and analysis

The injection process of the excited electrons can be deduced by the effect of SnO2 nanoparticles on the
fluorescence spectra of PbS quantum dots. Effect of SnO2 nanoparticles on the fluorescence spectra of Pbs
quantum dots is shown in Figure.3.

Figure 3: Effect of different drops of SnO2 nanoparticle on the luminescence of PbS quantun dots

In the toluene solution of PbS quantum dot, the peak intensity of PbS quantun dots is decreased when SnO 2
nanoparticles are injected. This means the fluorescence quenching. With the increase of the number of SnO 2,
the fluorescence peak intensity decreased.
Figure 4 shows the I-V curve quantum dot sensitized solar cell. It can be seen that the open circuit voltage
Voc=120mV and the short-circuit current is 0.38mA/cm2. The fill factor is 0.203, while the photoelectric
conversion efficiency is 0.0063%. The fill factor is relative low, and the main reason may be that the electronic
transmission ability of SnO2 nano crystal thin film is poor, which increase the inner battery resistances. The
main reason of the low open circuit voltage is the redox potential of the electrolyte close to the SnO 2
conduction band level. It can be increased according to the electrolyte with suitable redox potential.
The reason of low short circuit photocurrent is that the poor connection between quantum dots and nano
crystalline thin films, which affects the injection kinetics of the photo generated electrons. Therefore, based on

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the analysis of SnO2 nanocrystalline thin film solar cell sensitized by PbS quantum dots, the photoelectric
conversion efficiency of solar cells can be improved by structure adjustion, composition and process.

Figure 4: The l-V curve of SnO2 sensitized by PbS quantum dot

5. Conclusions

New energy is also known as non-conventional energy. It refers to the variety forms of energy outside
traditional energy sources, which including solar, geothermal energy, wind energy, oce an energy, biomass
and nuclear fusion energy, etc. Part of the renewable energy utilization technology has made considerable
development, and play an important role around the world. The technology of biomass, solar, wind,
hydroelectric power, geothermal energy and so on has been widely applied. In variety forms of the new
energy, solar cell is an important way to generate the power.
In order to increase the efficiency of the in organic solar cell, a compound of PbS quatum has been prepared
and applied to the solarcell. The experiment gives some results:
(1) In the toluene solution of PbS quantum dot, the peak intensity of PbS quantum dots will be decreased
when SnO2 nanoparticles are injected;
(2) The open circuit voltage and short-circuit current have some extent improvement.
(3) The fill factor is relative low due to the poor electronic transmission ability of SnO2 nano crystal thin film,
and the main reason of the low open circuit voltage is the redox potential of the electrolyte close to the SnO 2
conduction band level, and the reason of low short circuit photocurrent is that the poor connection between
quantum dots and nano crystalline thin films.
The experiment shows the validity of the preparation method of the PbS quantum dots and SnO2 solar cell.

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