List of Publications
Papers Published in Journals
1.
Electrical conduction mechanism of Polymer Dispersed CdSe/CdS Core/Shell Heterojunction
Diode
Mamta Sharma and S.K. Tripathi
Science of Advanced Materials 5 (2013) 1-10 (DOI:10.1166/sam.2013.1506) (In press) (Impact
Factor: 2.908).
2. Photoluminescence Study of CdSe Nanorods embedded in a PVA Matrix
Mamta Sharma and S.K. Tripathi
Journal of luminescence 135 (2013) 327 (Impact Factor: 2.367)
3. Analysis of Interface States and Series Resistance for Al/PVA:n-CdS Nanocomposite MetalSemiconductor and Metal-Insulator-Semiconductor Diode Structures.
Mamta Sharma and S.K. Tripathi
Applied Physics A 2013 (DOI 10.1007/s00339-013-7552-3) (Impact Factor: 1.63)
4. Studies on Green light emitting Polymer coated CdSe/ZnSe Core/Shell nanocrystals
S.K. Tripathi and Mamta Sharma
Material Research Bulletin 48 (2013) 1837 (Impact Factor: 1.9)
5. Preparation and nonlinear characterization of zinc selenide nanoparticles embedded in polymer
matrix.
Mamta Sharma and S.K. Tripathi
Journal of Physics and Chemistry of Solids 73 (2012) 1075 (Impact Factor: 1.56)
6. Study of Barrier Inhomogeneities in I–V-T and C-V-T Characteristics of Al/Al2O3/PVA:n-ZnSe MOS
Diode
Mamta Sharma and S.K. Tripathi
J. Appl. Phys. 112 (2012) 024521 (Impact Factor: 2.2)
7. Analysis of the forward and reverse bias I-V and C-V characteristics on Al/PVA:n-PbSe polymer
nanocomposites Schottky diode.
S. K. Tripathi and Mamta Sharma
J. Appl. Phys. 111 (2012) 074513 (Impact Factor: 2.2)
8. Temperature dependent current-voltage (I-V) characteristics of Al/n-Cadmium Selenide-Polyvinyl
alcohol (Al/n-CdSe-PVA) Schottky diode.
Mamta Sharma and S.K. Tripathi
Optoelectronics and Advanced Materials -Rapid Communications 6 (2012) 200 (Impact Factor:
0.38).
9. Investigations of Al:CdS/PVA nanocomposites: A joint theoretical and experimental approach
Vaneeta Bala, Mamta Sharma, S.K. Tripathi, Ranjan Kumar
Mat. Chem Phys. 146 (2014) 523-530 (Impact Factor: 2.2)
10. Synthesis and Characterization of TGA-capped CdTe nanoparticles Embedded in PVA Matrix
S. K. Tripathi, Ramneek Kaur and Mamta Sharma
Applied Physics A 2014 (Impact Factor: 1.63) (Accepted).
11. Temperature dependent capacitance-voltage measurement of Al/Al2O3/PVA:n−CdSe MIS diode
Mamta Sharma and S. K. Tripathi
AIP Conf. Proc. 1591 , 516 (2014).
12.Structural and Electrical Characterization of Ag Doped CdSe/PVA Nanocomposite Thin Film
Ramneek Kaur, Mamta Sharma and S. K. Tripathi
AIP Conf. Proc. 1536 (2013) 129.
13. Temperature Dependent I-V Characteristics of the Al/Rhodamine-6G/n-Si Organic MOS Diode
Anubhuti Tripathi and Mamta Sharma
AIP Conf. Proc. 1536 (2013) 317.
14. Temperature dependent barrier height of MIS diode of Al/Al2O3/n-CdSe/CdS/PVA Core/shell
quantum dot.
Mamta Sharma and S. K. Tripathi
AIP Conf. Proc. 1447 (2012) 349
15. Frequency Dependent Electrical Characterization of Al/Al2O3/PbSe/PVA MIS Diode.
Isha Gawri, Mamta Sharma and S. K. Tripathi
AIP Conf. Proc. 1393 (2011) 281
16. Preparation and Characterization of CdSe/CdS/PVA Core/shell Material.
Anny Narang, Gurvir Kaur, Mamta Sharma and S.K. Tripathi
AIP Conf. Proc. 1393 (2011) 193.
17. Third Order Optical Nonlinearity of CdSe/PVA Nanocomposites
Mamta Sharma and S.K. Tripathi
AIP Conf. Proc. 1393 (2011) 115.
18. In-situ generation of CdSe Nanorods in PVA Matrix
Mamta Sharma, Anny Narang, Gurvir Kaur and S.K. Tripathi
AIP Conf. Proc. 1313 (2010) 189.
19. Fabrication and Characterization of MIS Diode of Al/Al2O3/PVA:n-CdSe Nanocomposite Film
Mamta Sharma and S.K. Tripathi
Emerging Paradisms in nanotechnology (2012) 577-584. (ISBN-9788131789919).
20. Synthesis and characterization of nanocomposite of polyvinyl alcohol and lead selenide
nanoparticles
S.K. Tripathi, Samandeep and Mamta Sharma
Proceedings of National Conference on Recent Advances in Condensed Matter Physics (RACMP
2009) pp. 211-215.
21.Synthesis and Electrical Characterization of CdS Nanoparticles Dispersed in PVA matrix
Mamta Sharma and S.K. Tripathi
J Applied Physics 2014 (Communicated).
22. Frequency Dependent Electrical Characteristics of Al/Al2O3/PVA:n-ZnSe Metal- OxideSemiconductor Diode.
Mamta Sharma and S. K. Tripathi
J Material Science: Mater in Electronics 2014(Communicated).
23. Study of Linear and Nonlinear Optical Properties of Ag Doped CdSe/PVA Nanocomposite Film
S. K. Tripathi, Ramneek Kaur and Mamta Sharma
Physica E 2014 (Communicated).
24. Change in the properties of CdSe polymer nanocomposite with Ag doping
S. K. Tripathi, Ramneek Kaur and Mamta Sharma
Physica Status Solidi B: Basic Solid State Physics 2014 (Communicated).
Paper Presented in International and national Conferences
1. Influence of interface states and series resistance in metal-semiconductor structures
Mamta Sharma and S. K. Tripathi
International Conference on Polymers on the frontier of Science and Technology (APA 2013) Feb
21-23, 2013, Panjab University, Chandigarh (Poster)
2. ZnSe/PVA Polymer nanocomposite for nonlinear Devices
S.K. Tripathi and Mamta Sharma
International Conference on Polymer Science and Engineering: Emerging Dimensions, PSE 2010,
Nov 26-27, 2010, Panjab University, Chandigarh (Poster)
3. Temperature dependent barrier height of Al/n-PbSe-PVA/Al Schottky diode
Mamta Sharma and S. K. Tripathi
International conference on advances in nanotechnology Nov 06-08, 2008, MATS University,
Raipur (Poster)
4. Synthesis and Characterization of Polymer Doped II-VI Core/Shell System
Mamta Sharma, Ramneek Kaur and S. K. Tripathi
7th Chandigarh Science Congress (CHASCON 2013), 1-3 March, 2013, Panjab University,
Chandigarh (Poster)
5. Temperature dependent I-V Characteristics of Schottky diode of CdSe/PVA Nanocomposites
Mamta Sharma and S. K. Tripathi
23th Annual general Meeting Materials Research Society of India (MRSI-2012) Feb 13-15, 2012,
Thapar University, Patiala (poster)
6. Evaluation of Third Order Nonlinear Optical Parameters of CdSe/ZnSe Core/Shell Quantum Dots
Dispersed in PVA
Mamta Sharma, Ramneek Kaur and S. K. Tripathi
6th Chandigarh Science Congress (CHASCON 2012), 26-28 Feb, 2012, Panjab University,
Chandigarh (Poster)
7. Preparation and Characterization of CdSe/CdS Core/Shell nanoparticles
Gurvir Kaur, Mamta Sharma and S. K. Tripathi
2nd National Conference on Advanced Materials and Radiation Physics (AMRP-2011), Nov 4-5,
2011 SLIET, Longowal, Sangrur (Oral)
8. Electrical Studies on CdSe/PVA Polymer nanocomposites Film
Mamta Sharma and S. K. Tripathi
5th Chandigarh Science Congress (CHASCON-2011), 26-28 Feb, 2011, Panjab University,
Chandigarh (Best Poster)
9. Synthesis and Characterization of n-PbSe nanorods Dispersed in PVA matrix
Mamta Sharma, Gurvir Kaur and S.K. Tripathi
National Level Seminar on Emerging Trends in Nanotechnology Mar 30-31, 2010, SD College,
Ambala (Oral)
10. Study Of Optical Nonlinearity Of Chalcogenide Thin Film By Z-scan technique
Mamta Sharma and S. K. Tripathi
4th Chandigarh Science Congress (CHASCON 2010), 19-20 Feb, 2010, Panjab University,
Chandigarh (Poster)
11. Electrolytic Deposition of Alumina Film as an Oxide Layer for MOS Devices
Isha Gawri, Mamta Sharma and S.K. Tripathi
National conference on Emerging Perspectives and Sustainable Developments in Physics Nov 1819, 2009, DAV College, Abohar (Oral)
12. I-V and C-V Characteristics of Metal/n-PbSe-PVA Structure
Mamta Sharma and S. K. Tripathi
3rd Chandigarh Science Congress (CHASCON 2009), 26-28 Feb, 2009, Panjab University,
Chandigarh (Poster)
13. Fabrication and characterization of Schottky diode from n-PbSe dispersed in polymer matrix
S.K. Tripathi and Mamta Sharma
National Conference on ‘Nano: The Next revolution” Dec 4-5, 2008, DAV College, Dasuya (Poster).
A) Detailed Research Plan: II-VI Nanostructured materials for Organic-Inorganic Hybrid Solar Cells
Application
Origin of Proposal:
Organic-inorganic hybrid photovoltaic cells are among a hot topic of investigations due to their promising features such as
low fabrication cost, flexibility, and lightweight [1]. Furthermore, solution processability, high hole mobility and strong
visible absorption properties of conjugated polymers can be combined with high electron mobility, high electron affinity
and tunable optical properties of semiconducting nanocrystals to overcome the low power conversion efficiency of
organic solar cells [2]. The main factors attributed to the low power conversion efficiency of organic solar cells are low
carrier mobility, lack of absorption in the red/near infrared (NIR) part of the spectrum, poor environmental stability and
excitonic character of photo carrier generation [3]. The binding energy of excitons is in the order of 0.1 eV, hence room
temperature thermal excitation (25 meV) is too small to create free charge carriers [3]. Thus, it is necessary to select two
materials with sufficient electron affinity differences, such that the electron goes to the material with high electron affinity
and the hole goes to the material with low electron affinity after being dissociated at the donor/acceptor interface. The
exciton diffusion length is small for organic semiconductors, around 10 nm for poly[2,6-(4,4-bis-(2-ethylhexyl)-4Hcyclopenta[2,1-b;3,4-b0]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT); as a result nanoscale phase
separation must be achieved between the active organic and inorganic semiconductors, that must be within the exciton
diffusion length, otherwise the charge carriers will recombine before reaching to the donor/acceptor interface [4]. In
addition to this, to collect the charge carriers at the respective electrodes there must be an electrically continuous path
from the interface where the charge carriers are generated to the electrodes. If the size of organic/or inorganic domain is
too small, it will be difficult to form continuous conduction path and hence the charge collection efficiency will decrease.
On the other hand, if the domain sizes are too large, excitons will not be able to reach at the donor/acceptor interface
limiting the performance of hybrid solar cells. Therefore, to achieve a solar cell with good power conversion efficiency, it is
necessary to control the domain size.
These hybrid polymers/inorganic nanoparticle bulk heterojunction can take advantage of the beneficial
properties of both types of materials such as solution processing of polymer semiconductors and high electron mobility of
inorganic semiconductors. There are large number of studies has been reported on the improvement of hybrid solar cell
performance by replacing organic and inorganic materials. Table 1 displays performance characteristics of various hybrid
solar cells which show a variety of inorganic acceptor materials, as well as some variation in polymeric donor.
Out of all these reported inorganic/organic hybrid solar cells, Ren et al [2] has reported the highest PCE ~ 4% for
hybrid solar cells made of CdS quantum dots and polymer P3HT. After that, Dayal et al [9] reported a PCE of more than 3%
from the hybrid solar cells made of CdSe tetrapods and a low band gap polymer PCPDTBT. This increase in PCE is largely
due to the wider absorption range offered by PCPDTBT.
Table 1 shows performance characteristics of various hybrid solar cells
Reference
Ren et al, 2011 [2]
Dowland et al, 2011 [3]
Kwak et al, 2009[4]
Zhong et al, 2012 [5]
Jeltsch et al, 2012 [6]
Zhou et al, 2012 [7]
Celik et al,2012 [8]
Acceptor
Donor
CdS QD
CdS NC
CdS NW
CdS NP
CdSe NR:QD
CdSe NPs
CdSe NR
P3HT
P3HT
P3HT
P3HT
PCPDTBT
PCPDTBT
PCPDTBT
Jsc (mA/cm2)
10.9
4.84
5.26
5.34
13.8
9.20
12.1
Voc
(V)
1.10
0.84
0.60
0.52
0.48
0.78
0.63
FF
0.35
0.53
0.54
0.38
0.51
0.49
0.45
PCE
(%)
4.10
2.17
1.73
1.06
3.64
3.50
3.42
Dayal et al, 2010 [9]
Zhou et al, 2011 [10]
Kuo et al, 2011 [11]
Zhou et al, 2011 [12]
Radychevet al, 2012 [13]
Greaney et al, 2011 [14]
Olson et al, 2011 [15]
Chen et al, 2011 [16]
CdSe TR
CdSe NR:QD
CdSe TR
CdSe QD
CdSe QD
CdSe NC
CdSe NR
CdTe TP
Yu et al, 2011 [17]
Yu et al, 2011 [18]
Andrew et al, 2011 [19]
Lin et al, 2011 [20]
Wu et al, 2009 [21]
Beek et al, 2009 [22]
CdTe QD
CuInSe2
PbS QD
TiO2
TiO2 NR
ZnO
PCPDTBT
PCPDTBT
PDTTTPD
PCPDTBT
P3HT
P3HT
P3HT
PSBTBTNH2
PPV
P3HT
P3HT
P3HT
P3HT
P3HT
10.1
8.60
7.26
8.30
5.62
6.50
3.87
7.23
0.68
0.63
0.88
0.59
0.80
0.70
0.64
0.79
0.51
0.56
0.46
0.56
0.43
0.42
0.53
0.57
3.19
3.10
2.90
2.70
1.90
1.90
1.30
3.20
10.7
8.07
1.00
4.71
4.33
5.20
0.50
0.34
0.42
0.87
0.78
0.75
0.40
0.53
0.39
0.68
0.65
0.52
2.14
1.43
0.16
2.81
2.20
2.00
The principal criteria for the effective solar light-to-electric power conversion: (i) high absorption of light; (ii)
sufficient charge transport. To meet the first point one needs a material harvesting photons from the sufficient amount of
solar spectrum (as shown in figure 1(a)). The first step was a selection of nanosized PV materials incorporated preferably
into transparent or semitransparent polymer matrix. On one hand, such a design has provided a relative transparency of
the composite film due to the fact that the size of the nanoparticles (NPs) is much smaller than the wavelength of visible
light, so that the sample volume can be illuminated completely, and also this results in a substantial increase of the
effective area of heterojunction. The next step was a selection of polymer matrix. Recently, research attention has focussed
on Cyclopentadi-thiophene-based polymers as donor materials. These are found to be promising candidates due to their
narrower band gap compared to thiophene-based polymers resulting in enhanced photon absorption. It displays
maximum obtainable photocurrent density (secondary axis) which is derived from AM 1.5G photon flux (primary
axis).This is calculated using the assumption that EQE is 100% for all wavelengths. The band gap and maximum
obtainable Jsc for multiple polymers, as well as bulk silicon, is shown figure 1(b). This indicates that the potential Jsc for this
low band gap polymer is much higher than that of P3HT. It appears as though these low band gap polymers may lead the
way for future improvements in PCE for hybrid devices.
Operational stability of OSCs is one of the challenges in realizing low cost and large scale solar cells. Many efforts
have been carried out to improve the stability of OSC and one of the methods is to improve the stability of the active layer
components by addition of buffer layer. Qian et al [23] has report on hybrid polymer-CdSe solar cells with a ZnO
nanoparticle buffer layer with improved efficiency and lifetime.
Figure 1(a): Left figure shows an array of nanorod and nanotube materials positioned as a function of their band gaps in
respect to the solar irradiance spectrum shown by the red curve [24]. Right figure 1(b) Maximum obtainable values of
current density (red) for multiple materials, as determined by AM 1.5G photon flux (black) [1].
References:
1.
M. Wright, A. Uddin, Solar Energy Materials & Solar Cells 107 (2012) 87–111
2.
S. Ren, L.-Y. Chang, S.-K. Lim, J. Zhao, M. Smith, N. Zhao et al, Nano Letters 11 (2011) 3998–4002.
3.
S. Dowland, T. Lutz, A. Ward, S.P. King, A. Sudlow et al, Advanced Materials 23 (2011) 2739–2744.
4.
W.-C. Kwak, T.G. Kim, W. Lee et al, The Journal of Physical Chemistry C 113 (2009) 1615–1619.
5.
M. Zhong, D. Yang, J. Zhang, J. Shi et al, Solar Energy Materials and Solar Cells 96 (2012) 160–165.
6.
K.F. Jeltsch, M. Schadel et al, Advanced Functional Materials 22 (2012)397–404.
7.
R. Zhou, Y. Zheng, L. Qian et al, Nanoscale 4(2012)3507–3514.
8.
D. Celik, M. Krueger, C. Veit et al, Solar Energy Materials and Solar Cells 98 (2012) 433–440.
9.
S. Dayal, N. Kopidakis, D.C. Olson et al, Nano Letters 10 (2009) 239–242.
10. Y. Zhou, M. Eck, C. Men et al, Solar Energy Materials and Solar Cells 95 (2011) 3227–3232.
11. C.-Y. Kuo, M.-S. Su, G.-Y. Chen et al, Energy & Environmental Science 4 (2011) 2316–2322.
12. Y. Zhou, M. Eck, C. Veit et al, Solar Energy Materials and Solar Cells 95 (2011) 1232–1237.
13. M.J. Greaney, S. Das, D.H. Webber et al, ACS Nano 6 (2012) 4222–4230.
14. J. Yang, A. Tang, R. Zhou, J. Xue et al, Solar Energy Materials and Solar Cells 95 (2011) 476–482.
15. J.Y. Lek, L. Xi, B.E. Kardynal, L.H. Wong et al, ACS Applied Materials & Interfaces 3 (2011) 287–292.
16. H.-C. Chen, C.-W. Lai, I.C. Wu et al, Advanced Materials 23 (2011) 5451–5455.
17. W. Yu, H. Zhang, Z. Fan, J. Zhang et al, Energy & Environmental Science 112 (2011) 2831–2834.
18. Y.-Y. Yu, W.-C. Chien, Y.-H. Ko et al, Thin Solid Films 520 (2011) 1503–1510.
19. A. Guchhait, A.K. Rath, A.J. Pal et al , Solar Energy Materials and Solar Cells 95 (2011) 651–656
20. Y.-Y. Lin, T.-H. Chu, S.-S. Li, et al, Journal of the American Chemical Society 131(2009)3644–3649.
21. M.-C. Wu, C.-H. Chang, H.-H. Lo et al, Journal of Materials Chemistry 18(2008)4097–4102.
22. S.D. Oosterhout, M.M. Wienk et al, Nature Materials 8 (2009) 818–824.
23. L. Qian, J. Yang, R. Zhou et al, Journal of Materials Chemistry 21 (2011) 3814-3817.
24. V. V. Kislyuk and O. P. Dimitriev, Journal of Nanoscience and Nanotechnology 8 (2008) 131–148.
Objectives: The objectives of this research work are aiming to fabricate, optimize, model, and characterize ‘bulkheterojunction’ nanocomposites for photovoltaics. The motivation for using nanostructured materials emerges from the
specific optical properties of nanostructures.
1.
These nanocomposites consist out of using PCPDTBT low band gap conductive polymers as electron donors and CdS
quantum dots as electron acceptors.
2.
Use of solution-processed ZnO nanoparticle buffer layer in hybrid solar cells based on blends of PCPDTBT and CdS
quantum dots. The presence of the ZnO nanoparticle layer also drastically improves the stability of these hybrid solar
cells.
3.
Assembling and testing of organic solar cells based on these materials is the major focus of this research. The NCspolymer hybrid materials will be optimized.
4.
Our intention is to enhance the carrier mobility and balance the electron and hole transport within the system.
Improvements are expected by using appropriate ligand-covered NCs and nanocomposites out of NCs.
Brief outline of methodology to be adopted:
The first step involves the synthesis of CdS quantum dots by chemical processing technique and their incorporation into
PCPDTBT polymer matrix.
The second step involves nanoparticles characterization. It is necessary to establish understanding and control of
nanoparticle synthesis and applications. The as prepared materials will be characterized using Transmission Electron
Microscope (TEM) (morphology), X-ray diffraction (XRD) (structure, size and strain), FTIR, PL spectroscopy. Optical
parameters (refractive index (n), absorption coefficient (α), extinction coefficient (k), and optical band gap (E g) will gives
us good information about band gap and optical transparency of the materials. Conductivity measurement (determine the
energy distribution of various species of gap states) is a valuable diagnostic tool for the material quality.
The third step will involve hybrid solar cell fabrication. The hybrid device generally has a transparent anode
through which light enters. Indium tin oxide (ITO) is used for this purpose. A layer of the conductive polymer mixture
PEDOT:PSS will be applied between anode and the active layer as hole transporter. Next, on the top of the PEDOT:PSS, an
active layer will be deposited which holds the responsibility for light absorption, exciton generation/dissociation and
charge carrier diffusion. The active layer is made up of two materials namely PCPDTBT donor and CdS acceptor. The
cathode materials will be Al, Ca or Mg.
The fourth step will be characterization and estimation of efficiency of hybrid solar cells. The as prepared device
is characterized by I-V and C-V measurements under the illumination of light. The solar cell parameters i.e. Air mass, Opencircuit voltage (Voc), Short-circuit current (Isc), Maximum power point (MPP), Fill factor (FF), Power conversion efficiency
(PCE or ηe), Quantum efficiency (QE) will be measured on these materials. The absorption–transmittance spectra of the
devices will be recorded with UV-VIS-near IR Absorption spectrometer. The electrical and optical properties will be
optimizing to explain the experimental results. Hybrid solar cells efficiencies will be optimized by using different low band
gap polymers and addition of different buffer layer to enhance the stability of hybrid solar cells.
Efforts will be made to get patented the fabricated new materials and their properties for industrial use. The
results will be published in reputed journals for further use by the researchers.
Of course, deviations from this scheme might occur due to unexpected problems or interesting findings might open new
different direction. For this proposed research, we have the most important facilities such as (1) Cleanroom equipped
with general processing facilities such as spin coating (2) thermal evaporator and optical microscope (3) A four point
probing bridge to measure the sheet resistance (4) Keithley 6517A electrometer for electrical characterization (5)Hioki
3532-50 LCR Hi-Tester (6) UV-VIS-near IR Absorption spectrometer for recording the absorption–transmittance spectra
of the devices (7) Quantum efficiency measurement system and solar simulator (need to be purchased).
Significance of proposal in context of current status:
From a technological point of view, the current challenges of organic solar cells are optimizing the power conversion
efficiency, lifetime, and achieving low cost for the modules made with organic solar cells. The above three are mutually
dependent on the way to commercialization. Development of solution processed organic solar cells is promising
developments towards higher efficiencies in photovoltaics. The one way to reduce manufacturing costs is to move away
from vacuum-based deposition processes, high processing temperatures, long processing times, and rigid, heavy, and
expensive substrates and to move toward solution-phase deposition processes, low-processing temperatures, short
processing times, and flexible, light, and cheap, substrates that can be scaled-up and utilized in “roll-to-roll” manufacturing
processes. Nanocomposites consisting of nanometer-sized clusters embedded in a dielectric matrix (cermets) have been
studied extensively and are presently applied as selective absorbers in solar collectors. Absorber coatings of this type are
presently produced on a large scale by several manufacturers and represent the example for industrial application of
nanostructured materials in solar energy technology. The nanoparticles embedded in relatively thick polymer foils are
currently discussed as optical materials in solar control glazing.
Prospects of this work extending to long-term project:
Solar cells based on organic molecules and conjugated polymers are a good alternative for the conventional solar cells due
to their potentially low manufacturing costs, their light weight and ease of processing but the low efficiency limits the use
of them in industry. We would like to extend this work to “Advanced parallel tandem structures for enhanced organic
solar cell efficiencies”. We would like to fabricate, optimize, model, and characterize solution processed organic tandem
solar cells. A tandem configuration can be used to overcome the low efficiency limitation in organic cell devices. Tandem
solar cells made from thermally evaporated molecules already show efficiencies above 10%. We propose the development
and characterization of solution processed organic tandem solar cells which are easier to fabricate. This will lead to the
development of cheap solar cells with higher conversion efficiencies.
The possible way to improve the efficiency is by using a tandem configuration in which two or more cells with different
absorption spectra, i.e., different band gaps, are stacked. This increases the absorption of solar light and allows utilizing
the photon energy more efficiently. The organic “tandem cell” architecture is a multilayer structure that is equivalent to
two photovoltaic cells, in which a transparent intermediate layer is positioned between the two active layers.