1. Problem to be investigated: Fabrication of

1. Problem to be investigated:
Fabrication of copper zinc tin sulphide (CZTS) based thin film solar cells through spray
technique.
2. Objectives
1. Fabricate thin film solar cells with reasonable efficiency (3-4 %), using CZTS as absorber
and indium sulphide (In2S3) as buffer layer employing chemical spray pyrolysis (CSP)
technique. Demonstration of large area solar cell (5 cm X 5 cm).
2. Fabricate thin film solar cells with reasonable efficiency (3-4 %), using CZTS as absorber
and zinc sulphide (ZnS) as buffer layer employing CSP technique. Demonstration of
large area solar cell (5 cm X 5 cm).
3. Summary of the proposed work
In the proposed work, fabrication of CZTS based solar cells using chemical spray pyrolysis is
intended. The initial 16 months will be utilized to obtain 3-4% efficient solar cells [on small
area as well as large area] using CZTS absorber and In2S3 buffer layer. The next 16 months
will be focussed on fabrication of CZTS based cells using ZnS as buffer layer. In the final
four months results obtained from the research work will be communicated.
4. Hypothesis:
We have been working in the field of thin film solar cells based on different absorber
materials like CuInS2, CuInSe2 and CuxS for the past three decades and reported on
fabrication of thin film solar cells with reasonable efficiency using these materials. CZTS is
another new promising alternative to CIGS, which has received a lot of attention over the
past few years. In the proposed work, CZTS is intended to be used as absorber which would
be cost-wise and toxicity level-wise a friendly option. In2S3 and ZnS are two candidates
proposed as the materials for buffer layer. In most of the high efficiency cells reported, CdS
is used as buffer layer. In2S3 is a photosensitive material whereas ZnS would be a good
option from the lattice-matching point of view. Both In2S3 and ZnS are wide bandgap
materials with sub-band gap defects. It is expected that there will be an enhancement in
open-circuit voltage due to wider bandgap and absorption of sub-bandgap photons by the
defects.
5. Research design and methodology
Work plan
16 months
Junction fabrication using CZTS and In2S3 on ITO coated glass
substrates. Junction fabrication on large area (5 cm X 5 cm) ITO
coated substrates.
16 months
Junction fabrication using CZTS and ZnS on ITO coated glass
substrates. Junction fabrication on large area (5 cm X 5 cm) ITO
coated substrates.
4 months
Communication of results. Submission of report
6. Tools to be used in the study
We intend to characterize each layer of a solar cell separately and the completed devices also
using different techniques available with us, so that we can identify the effect of various
changes in deposition conditions on film properties.
Film and device characterization
1. JASCO V-570 UV-Vis-NIR spectrophotometer- to analyze the bandgap and presence of
defect absorption, if any. Transmittance of the films (especially of FTO) can also be
measured.
2. Photoluminescence (PL) set up- To identify various defects present in the films.
3. X-ray diffraction (XRD) studies- Identify the crystal structure, preferential orientation,
grain size etc.
4. Stylus profilometer- To measure the thickness and roughness of the deposited films and
to check the presence of pinholes, if any.
5. Atomic Force Microscope (AFM)- To monitor surface morphology
6. Hall measurement set up- To measure resistivity, carrier concentration, mobility, and
conductivity type.
7. X-Ray Photoelectron spectroscopy (XPS)- To identify the chemical state of each
element, atomic concentration of elements etc.
7. Significance of the study
Thin film solar cells are the sole economical solution to present day energy demands. But
not all materials can be used to develop thin film solar cells. They should match the
requirements for photo-energy conversion, should be non-hazardous and abundant. There
are only few materials like CuInS2, In2S3, SnS, SnS2, ZnO, FTO, Cu2ZnSnS4 etc. which are
suitable for PV device fabrication, where CuInS2, SnS and Cu2ZnSnS4 are absorber layer
materials and In2S3 and ZnS are important buffer layer materials. These materials are
comprised of earth abundant elements and in fact we have been able to deposit these
materials with defects in the bandgap. Defects within the bandgap can help absorb sub
bandgap photons also.
The significance of the present study lies in:
1. The choice of abundant and non-toxic suitable materials
2. The choice of the extremely economical deposition technique viz. chemical spray
pyrolysis. Extremely economical because only small quantity of material is required for
device fabrication.
8. It’s relevance to present day problems and needs of the society and country
We are on the verge of a serious shortage of non-renewable resources and solar energy is the
key to solving our concerns related to energy. Thin film solar cells are the promising
alternative to consumer friendly solar power.
Ours is a developing country and in order to cater to the growing energy demands in a
consumer friendly manner there is no other option but to go for cheap materials and low
cost processing techniques so that the final product viz. solar cell, is affordable. The
materials we intend to pursue work on are abundant and cheap. Our deposition technique is
also simple and cost effective. In that perspective our work addresses the needs of our
country. We have tried to eliminate toxic elements like ‘Cd’, ‘Se’ etc. So our work shall in no
way be hazardous to the society.
9. It’s likely contribution to knowledge
Existing PV technology revolves around ‘Si’ and ‘GaAs’ for some reasons or the other.
Theories have been developed for such type of solar cells. Success in works on solar cells
pursued on alternate materials and technology will for sure be an addition to the existing
database.
Budget
First year
Item
Consumables
Maintenance
Travel
Any other
Amount
(Rs.)
100000
100000
30000
100000
Second year
Item
Consumables
Maintenance
Travel
Any other
Amount
(Rs.)
100000
100000
30000
100000
Third year
Item
Amount
(Rs.)
Consumables 100000
Maintenance 100000
Travel
40000
Any other
100000
Total
330000
Grand total= Rs. 1000000/Emeritus
scientist
allowance
Total
330000
Total
340000
First year
Second year
Third year
Total (Rs.)
240000
240000
240000
720000
Total project cost: Rs. 17,20000/-
LIST OF PAPERS PUBLISHED IN INTERNATIONAL/NATIONAL JOURNALS
1. Lattice vibrations and eigen vector magnitudes in ZnS, K.P.Vijayakumar, C.Purushothaman and
C.S.Menon. Indian Journal of Pure and Applied Physics, Vol.19, p.749 (1981).
2. Effect of annealing on the reflectivity of silver thin films, K.P.Vijayakumar and C.Purushothaman.
Thin Solid Films, Vol.82, p.225 (1981).
3. Intrinsic stress measurement in silver thin films by using ellipsometry, K.P.Vijayakumar and
C.Purushothaman. Journal of Applied Physics, Vol.59, p.1787 (1986).
4. Ellipsometric study of spray pyrolysed CdS thin films, J.Nolly, K.K.Abdullah and K.P.Vijayakumar.
Physica Status Solidi, Vol.a101, p. E35 (1987).
5. Effect of annealing temperature on the electrical transport properties of spray pyrolysed CdS thin
films, A.G.Valyomana, K.P.Vijayakumar and C.Purushothaman. Journal of Material Science
Letters, Vol.9, p.1025 (1990).
6. An ellipsometric study of variations on the interlayer in chemically prepared CuxS/CdS bilayer thin
films, K.P.Vijayakumar. Journal of Applied Physics, Vol.69, p.6771 (1991).
7. Variations of interlayer structure in CuxS/CdS bilayer thin film with annealing of CdS: an
Ellipsometric study, K.P.Vijayakumar. Bulletin of Materials Science, Vol.14, p.57 (1991).
8. Influence of annealing on lifetime of minority carriers in n-type CdS films, A.G.Valyomana,
K.P.Vijayakumar and C.Purushothaman. Journal of Materials Science Letters, Vol.11, p.616
(1992).
9. Photoconductive and ellipsometric studies of spray pyrolysed CdS thin films, A.G.Valyomana, Sunny
Mathew, K.P.Vijayakumar and C.Purushothaman. Bulletin of Materials Science, Vol.15, p.355
(1992).
10. Ellipsometric studies on SnO2/CdS interfaces, Sunny Mathew and K.P.Vijayakumar. Journal of
Optics, Vol.23 (3), p.115 (1994)
11. Optical constants of CdS thin films prepared by spray pyrolysis, Sunny Mathew and
K.P.Vijayakumar. Bulletin of Materials Science, Vol.17, p.225 (1994).
12. Optical and surface properties of spray pyrolysed CdS thin films, Sunny Mathew, P.S.Mukherjee and
K.P.Vijayakumar. Thin Solid Films, Vol.254, p.278 (1995).
13. Ellipsometric studies of microscopic surface roughness of CdS thin films, Sunny Mathew and
K.P.Vijayakumar. Bulletin of Materials Science, Vol.17, p.421 (1994).
14. Room temperature deposition of CuInSe2 thin films by chemical methods, P.K.Vidyadharan Pillai,
P.S.Mukherjee and K.P.Vijayakumar. Journal of Materials Science Letters, Vol.13, p.1725 (1994).
15. Characterization of spray pyrolysed CdS thin films doped with Cu, Sunny Mathew, P.S.Mukherjee
and K.P.Vijayakumar. Japanese Journal of Applied Physics, Vol.34, Part I, No.2A, p.4940
(1995).
16. Fabrication of homojunction using spray pyrolysed CdS thin film by copper diffusion, K.P.Varkey
and K.P.Vijayakumar. Japanese Journal of Applied Physics, Pt2, Vol.36, No.4A, p. L394 (1997).
17. Characterization of CuInSe2/CdS thin film solar cell prepared using CBD, P.K.Vidyadharan Pillai
and K.P.Vijayakumar. Solar Energy Materials and Solar Cells, Vol.51, p.47 (1998).
18. Chemical bath deposition of CdS thin films and its partial conversion to CdO on annealing,
K.L.Narayanan, K.P.Vijayakumar, K.G.M.Nair and G.V.N.Rao. Bulletin of Materials Science,
Vol.12 (5), p.1 (1997).
19. Structural transformation of dip coated CdS thin films during annealing, K.L.Narayanan,
K.P.Vijayakumar, K.G.M.Nair, N.S.Thampi and K.Krishan. Journal of Materials Science, Vol.32,
p.4837 (1997).
20. Raman scattering and optical absorption studies of Ar+ implanted CdS thin films, K.L.Narayanan,
K.P.Vijayakumar, K.G.M.Nair, B.Sundarakkannan, G.V.N.Rao and R.Kesavamoorthy. Nuc. Inst.
and Methods B, Vol.132, p.61 (1997).
21. Effect of irradiation induced disorder on the optical absorption spectra of CdS thin films,
K.L.Narayanan, K.P.Vijayakumar, K.G.M.Nair and N.S.Thampi. Physica B, Vol.240, p.8 (1997).
22. Depth profiling of CdS homojunction using AES analysis, K.P.Varkey, K.P.Vijayakumar, Jun Imai,
Toshihiro Toshida and Yasube Kashiwaba. Bulletin of Materials Science, Vol.20, p.1 (1997).
23. Electrical studies on trap levels present in n and p-type spray pyrolysed CdS thin films, N.A.Zeenath,
K.P.Varkey and K.P.Vijayakumar. Journal of Physics-Condensed Matter, Vol.10, p.2053 (1998).
24. Raman scattering studies of Ar+ implanted CdS thin films prepared by vacuum evaporation,
K.L.Narayanan, K.P.Vijayakumar, K.G.M.Nair and R.Kesavamoorthy. Physica Status. Solidi-A,
Vol.164, p.752 (1997).
25. Positron beam studies of argon irradiated CdS thin films, G.Amarendra, K.L.Narayanan,
G.Venugopal Rao, B.Viswanathan, K.G.M.Nair and K.P.Vijayakumar. Journal of Applied Physics,
Vol.84, No (8), p.4448 (1998).
26. Spray pyrolysed thin film CdS homojunction solar cell with improved performance, K.P.Varkey,
K.P.Vijayakumar, T.Yoshida and Y.Kashiwaba. Renewable Energy, Vol.18, p.465 (1999).
27. Study of trap levels by electrical techniques in p-type CuInSe2 thin films prepared using chemical
bath deposition, N.A.Zeenath, P.K.V.Pillai, K.Bindu, M.Lakshmi and K.P.Vijayakumar. Journal of
Material Science, Vol.35, p.1 (2000).
28. Preparation of CuInS2 thin film using CBD CuxS films, S.Bini, K.Bindu, M.Lakshmi, C.Sudha
Kartha, K.P.Vijayakumar, Y.Kashiwaba and T.Abe. Renewable Energy, Vol.20, No.(4), p.405
(2000).
29. Chemical bath deposition of different phases of copper selenide thin films by controlling bath
parameters, M.Lakshmi, K.Bindu, S.Bini, K.P.Vijayakumar, C.Sudha Kartha, T.Abe and
Y.Kashiwaba. Thin Solid Films, Vol.370, p.89 (2000).
30. Reversible Cu2-xSe<> Cu3Se2 transformation in Copper Selenide thin films prepared by CBD,
M.Lakshmi, K.Bindu, S.Bini, K.P.Vijayakumar, C.Sudha Kartha, T.Abe and Y.Kashiwaba. Thin
Solid Films, Vol.386, p.127 (2001).
31. Irradiation induced persistent photoconductivity in CdS films prepared by chemical bath deposition,
K.L. Narayanan,R.Rajaraman,M.C.Valsakumar,K.P.Vijayakumar and K.G.M.Nair. Optical
Materials, Vol.17, p.355 (2002).
32. Amorphous selenium films prepared using CBD: Optimisation of deposition process and
charcterisation, K.Bindu, M.Lakshmi, S.Bini,K.P.Vijayakumar,C.Sudha Kartha,T.Abe and
Y.Kashiwaba. Semiconductor Science and Technology,Vol.17, p.270 (2002).
33. Structural, optical and electrical properties of In2Se3 thin films formed by annealing chemically
deposited Se and vacuum evaporated ‘In’ stack layers. K.Bindu, C.Sudha Kartha,
K.P.Vijayakumar,Y.Kashiwaba and T.Abe. Applied Surface Science Vol.191, p.138 (2002).
34. Effect of size quantisation in the I-V characteristics of CdS bulk nano junctions, K.B.Jinesh, C.Sudha
Kartha and K.P.Vijayakumar. Applied Surface Science, Vol.195, p.263 (2002).
35. Role of excess cadmium in the electrical properties of nano devices made of chemically deposited
nano CdS, K.B.Jinesh,C.Sudha Kartha and K.P.Vijayakumar. Applied Surface Science,Vol.207,
p.26 (2003).
36. CuInSe2 thin film preparation through a new selenisation process using chemical bath deposited
selenium, K.Bindu, C.Sudha Kartha, K.P.Vijayakumar, T.Abe and Y.Kashiwaba. Solar Energy
Materials and Solar Cells,Vol.79, p.67 (2003).
37. Characterisation of spray pyrolysed Indium Sulfide thin films, Teny Theresa John, S.Bini,
Y.Kashiwaba, T.Abe, Y.Yasuhiro, C.Sudha Kartha and K.P.Vijayakumar…..Citation Index: 75.
Semiconductor Science and Technology, Vol.18, p.491 (2003).
38. How quantum confinement comes in chemically deposited CdS? -A detailed XPS investigation,
K.B.Jinesh, K.C.Wilson, S.V.Thampi, C.Sudha kartha and K.P.Vijayakumar. Physics-E, Vol.19(3),
p.303 (2003).
39. Defect characterization of spray pyrolysed beta In2S3 thin film using thermally stimulated current
measurement, Rupa R.Pai, Teny Theresa John, Y.Kashiwaba, T.Abe, K.P.Vijayakumar and C.Sudha
Kartha. Journal of Materials Science, Vol.40, p.741(2005).
40. Studies on Ar+ implanted CdS thin films using photothermal deflection technique, M.Paul Raj,
S.Ram Kumar, K.P.Vijayakumar, C.Sudha Kartha, P.Magudapathy, K.G.M.Nair and B.Viswanathan.
Nuclear Instruments and Methods in Physics Research-B,Vol.122(1-2), p.123 (2004).
41. Observation of phase transitions in chemical bath deposited copper selenide thin films through
conductivity studies, Rupa R.Pai, Teny Theresa John, M.Lakshmi, K.P.Vijayakumar and C.Sudha
Kartha. Thin Solid Films, Vol.473(2), p.208 (2005).
42. CuInS2 films using repeated chemical spray pyrolysis, Teny Theresa John, K.C.Wilson, P.M.Ratheesh
Kumar, C.Sudha Kartha, K.P.Vijayakumar, Y.Kashiwaba, T.Abe and Y.Yasuhiro. Physica Status
Solidi (a), Vol.202, p.79 (2005).
43. Modifications of ZnO thin films under dense electronic excitation, P.M.Ratheesh Kumar, C.Sudha
Kartha, K.P.Vijayakumar, F.Singh, D.K.Avasthi, T.Abe, Y.Kashiwaba, G.S.Okhram, M.Kumar and
Sarvesh Kumar. Journal of Applied Physics,Vol.97, p.13509 (2005).
44. On the properties of Indium doped ZnO thin films, P.M.Ratheesh Kumar, C.Sudha Kartha,
K.P.Vijayakumar, T.Abe, Y.Kashiwaba, F.Singh and D.K.Avasthi….Citation Index:69.
Semiconductor Science and Technology, Vol.20, p.120 (2005).
45. CuInS2/In2S3 thin film solar cell using spray pyrolysis technique having 9.5% efficiency, Teny
Theresa John, Meril Mathew, C.Sudha Kartha, K.P.Vijayakumar, T.Abe and Y.Kashiwaba.
Solar energy Materials and Solar Cells, Vol.89, p.27 (2005).
46. Characterisation of undoped and Cu doped CdS thin films using photo thermal and other
techniques, M.Paulraj, S.Ramkumar, K.P.Varkey, K.P.Vijayakumar, C.Sudha Kartha and
K.G.M.Nair.
Physica Status Solidi(a), Vol.202, p.425 (2005).
47. Effect of fluorine doping on structural, electrical and optical properties of ZnO thin films,
P.M.Ratheesh Kumar, C.Sudha Kartha, K.P.Vijayakumar, F.Singh and D.K.Avasthi. Materials
Science & Engineering (B), Vol.117, p.307 (2005).
48. Preparation of indium sulfide thin films by spray pyrolysis using a new precursor indium nitrate,
Teny Theresa John, C.Sudha Kartha, K.P.Vijayakumar, T.Abe and Y.Kashiwaba. Applied Surface
Science, Vol.252, p.1360 (2005).
49. Influence of substrate temperature on the properties of vacuum evaporated InSb films, V.Senthil
Kumar, S.Venkatachalam, C.Viswanathan, S.Gopal, Sa.K.Narayandass, D.Mangal Raj, K.C.Wilson
and K.P.Vijayakumar. Crystal Growth Technology, Vol.40, p.573 (2005).
50. Doping of spray pyrolysed ZnO thin films through direct diffusion of indium: Structural, optical and
electrical studies, P.M.Ratheesh Kumar, C.Sudha Kartha and K.P.Vijayakumar. Journal of Applied
Physics, Vol.98, p.23509 (2005).
51. Characterisation of In2S3 and ZnO thin films for photovoltaic application using Photo thermal
deflection technique, M.Paulraj, S.Ramkumar, P.R.Amjith, T.Theresa John, P.M.Ratheesh Kumar,
C.Sudha Kartha, K.P.Vijayakumar and K.G.M. Nair. Journal de Physique IV, Vol.125, p.469
(2005).
52. Photo thermal imaging of He+ ion implanted CdS, M.Paulraj, S.Ramkumar, K.P.Vijayakumar,
C.Sudha Kartha and K.G.M.Nair. Journal de Physique IV, Vol.125, p.97 (2005).
53. Modification in cell structure for better performance of spray pyrolysed CuInS2/In2S3 thin film solar
cells, Teny Theresa John, C.Sudha Kartha, K.P.Vijayakumar, T.Abe and Y.Kashiwaba. Applied
Physics A, Vol.82, p.703 (2006).
54. SHI induced single phase InSe formation at low annealing temperature, R.Sreekumar, P.M.Ratheesh
Kumar, C.Sudha Kartha, K.P.Vijayakumar, D.Kabiraj, S.A.Khan and D.K.Avasthi. Nuclear
Instruments and Methods in Physics Research B, Vol.244, p.190 (2006).
55. SHI induced modifications in spray pyrolysed beta-In2S3 thin films, P.M.Ratheesh Kumar, Teny
Theresa John, C.Sudha Kartha and K.P.Vijayakumar. Nuclear Instruments and Methods in
Physics Research B, Vol.244, p.171 (2006).
56. Effect of thickness and post deposition annealing on the properties of evaporated In2S3 thin films,
P.M.Ratheesh Kumar, Teny Theresa John, C.Sudha Kartha, K.P.Vijayakumar, T.Abe and
Y.Kashiwaba. Journal of Materials Science, Vol.41, p.5519 (2006).
57. Defect analysis of sprayed beta – In2S3 thin films using photoluminescence studies, R.Jayakrishnan,
Teny Theresa John, C.Sudha Kartha, K.P.Vijayakumar, T.Abe and Y.Kashiwaba. Semiconductor
Science and Technology, Vol.20, p.1162 (2005).
58. Room temperature photo luminescence surface mapping, R.Jayakrishnan, Tina Sebastian, C.Sudha
Kartha and K.P.Vijayakumar. Journal of Physics: Conference Series, Vol.28, p.62 (2006).
59. Effect of oxygen implantation in spray pyrolysed ZnO thin films, K.P.Vijayakumar, P.M.Ratheesh
Kumar, C.Sudha Kartha, K.C.Wilson, F.Singh, K.G.M.Nair and Y.Kashiwaba. Physics Status Solidi
(a), Vol.283 (5), p.860 (2006).
60. Swift heavy ion induced interface mixing in In/Sb, R.Sreekumar, P.M.Ratheesh Kumar, C.Sudha
Kartha, K.P.Vijayakumar, D.Kabiraj, S.A.Khan, D.K.Avasthi, Y.Kashiwaba and T.Abe.
Semiconductor Science and Technology, Vol.21, p.1 (2006).
61. On the origin of blue-green luminescence in spray pyrolysed ZnO thin films, P.M.Ratheesh Kumar,
C.Sudha Kartha and K.P.Vijayakumar. Journal of Materials Science Vol.42, p.2598 (2007).
62. Spray pyrolysed beta-In2S3 thin films: Effect of post deposition annealing, Teny Theresa John,
C.Sudha Kartha, K.P.Vijayakumar, T.Abe and Y.Kashiwaba.Vacuum, Vol.80 (8), p.870 (2006).
63. Implantation assisted copper diffusion: a different approach for the preparation of CuInS 2/In2S3 p-n
junction, K.C.Wilson, Tina Sebastian, Teny Theresa John, C.Sudha Kartha and
K.P.Vijayakumar…..Citation Index:4. Applied Physics Letters, Vol.89, p.013510 (2006).
64. Tuning Donor-Acceptor and Free-bound transitions in CuInSe2/ITO heterostructures.
R.Jayakrishnan, K.G.Deepa, C.Sudha Kartha and K.P.Vijayakumar. Journal of Applied Physics,
Vol.100, p.04610L (2006).
65. Post deposition annealing effects on In2S3 thin films deposited using SILAR technique, R.Renjith,
Teny Theresa John, C.Sudha Kartha, K.P.Vijayakumar, T.Abe and Y.Kashiwaba. Materials Science
in Semiconductor Processing, Vol. 10, p.49 (2007).
66. Thermal diffusion of Cu into In2Se3: A better approach to SEL technique in the deposition of
CuInSe2 thin films, K.G.Deepa, P.M.Ratheesh Kumar, C.Sudha Kartha and K.P.Vijayakumar. Solar
Energy Materials and Solar Cells , Vol.90, p.3481 (2006).
67. Anomalous behavior of silver doped indium sulfide thin films, Meril Mathew, R.Jayakrishnan,
P.M.Ratheesh Kumar, C.Sudha Kartha, Y.Kashiwaba, T.Abe and K.P.Vijayakumar. Journal of
Applied Physics, Vol.100, p.033504 (2006).
68. Different phases of indium selenide prepared by annealing In/Se bilayer at various temperatures:
Characterisation studies, R.Sreekumar, R.Jayakrishnan, C.Sudha Kartha, K.P.Vijayakumar,
Y.Kashiwaba and T.Abe. Solar Energy Materials and Solar Cells, Vol.90 (17), p.2908 (2006).
69. Anomalous photoconductivity in gamma In2Se3, R.Sreekumar, R.Jayakrishnan, C.Sudha Kartha and
K.P.Vijayakumar. Journal of Applied Physics, Vol.100, p.033707 (2006).
70. Photo electrical properties of crystalline titanium dioxide thin films, R.Sathyamoorthy, P.Sudhagar,
P.Chandramohan and K.P.Vijayakumar. Crystal Research & Technology, Vol. 42 (5), p.498
(2007).
71. Photo conductivity in sprayed beta-In2S3 thin films under sub band gap excitation of 1.97 eV,
R.Jayakrishnan, Tina Sebastian, Teny Theresa John, C.Sudha Kartha and K.P.Vijayakumar. Journal
of Applied Physics, Vol.102, p.043109 (2007).
72. An investigation on the variations in properties of Ni+ irradiated ZnO thin films, P. M. Ratheesh
Kumar, C. Sudha Kartha, K. P. Vijayakumar, F. Singh and D.K. Avasthi. Radiation Effects and
Defects in Solids Vol. 163, p. 635 (2008).
73. Enhancement of band gap and photoconductivity in gamma indium selenide due to swift heavy ion
irradiation, R.Sreekumar, R.Jayakrishnan, C.Sudha Kartha, K.P.Vijayakumar, S.A.Khan and
D.K.Avasthi. Journal of Applied Physics, Vol.103, p.023709 (2008).
74. In2S3: Ag, An ideal buffer layer for thin film solar cells, Meril Mathew; C.Sudha Kartha, K.P.
Vijayakumar. Journal of Materials Science: Materials in Electronics, Vol. 20 (1), p.294 (2009).
75. Performance of indirect solar cabinet dryer, A.Sreekumar, P.E.Manikantan and K.P.Vijayakumar.
Energy Conversion and Management, Vol.49, p.1388-95 (2008).
76. Do the grain boundaries of beta-Indium Sulfide thin films have a role in sub-band gap photo
sensitivity to 632 nm? R.Jayakrishnan, Teny Theresa John, C.Sudha Kartha, K.P.Vijayakumar,
Deepthy Jain, L.S. Sharath Chandra and V.Ganesan .Journal of Applied Physics, Vol.103, p.53106
(2008).
77. Characterisation of spray pyrolysed CuInS2 thin films, Tina Sebastian, R.Jayakrishnan, C.Sudha
Kartha and K.P.Vijayakumar. Open Surface Science Journal, Vol.1, p.1-6 (2009).
78. Structural and Optical Properties of Indium Sulfide Thin Films, Anita R.Warrier, Teny Theresa John,
K.P.Vijayakumar and C.Sudha Kartha. The Open Condensed Matter Journal, Vol.2, p.9-14
(2009).
79. Sub-micrometer thick CuInSe2 films for solar cells using sequential elemental evaporation,
K.G.Deepa, R.Jayakrishnan, C.Sudha Kartha, K.P.Vijayakumar and V.Ganesan. Solar Energy, Vol.
83, p. 964-68 (2009).
80. Role of substrate temperature in controlling properties of sprayed CuInS 2 absorbers,Tina Sebastian,
Manju Gopinath, C. Sudha Kartha, K.P.Vijayakumar,T. Abe,Y. Kashiwaba. Solar Energy, Vol.83,
p. 1683-88 (2009).
81. Non destructive evaluation of carrier transport properties in CuInS2 and CuInSe2 thin films using
Photo Thermal Deflection technique. Anita R.Warrier, K.G.Deepa, Tina Sebastian, C.Sudha Kartha
and K.P.Vijayakumar. Thin Solid Films, Vol.518 (7), p. 1767-73 (2010).
82. Role of chlorine on the opto-electronic properties of beta-In2S3 thin films, Angel Susan Cherian,
Meril Mathew, C.Sudha Kartha and K.P.Vijayakumar. Thin Solid Films Vol. 518, p. 1779-1783
(2010).
83. Optimization of parameters of Chemical Spray Pyrolysis technique to get n and p-type layers of SnS,
T.H.Sajeesh. Anita R Warrier, C S Kartha, K P Vijayakumar. Thin Solid Films Vol 508, p.4370-74
(2010).
84. Tin doping in spray pyrolysed Indium Sulfide thin films for solar cell applications, Meril Mathew,
Manju Gopinath, C.Sudha Kartha, K.P.Vijayakumar, Y.Kashiwaba and T.Abe. Solar Energy, Vol.
84, p.888-97 (2010).
85. Transverse photo thermal beam deflection technique for determining the transport properties of
semiconductor thin films, Anita R Warrier, Tina Sebastian, C Sudha Kartha, K P Vijayakumar.
Journal of Applied Physics, Vol. 107, p.073701 (2010).
86. Unveiling defect levels of spray pyrolysed SnS films for photovoltaic applications using
photoluminescence technique, T.H.Sajeesh, N.Poornima, C.Sudha Kartha and K.P.Vijayakumar.
Physics Status Solidi (a), Vol. 207, p.1934-39 (2010).
87. On tuning the orientation of grains of spray pyrolysed ZnO thin films, T.V.Vimal Kumar, N.
Poornima, C. Sudha Kartha and K.P.Vijayakumar. Applied Surface Science, Vol. 256, p. 6025-28
(2010).
88. Inverted polymer solar cells with indium sulfide electron selective layer, M.R.Rajesh Menon,
M.V.Maheshkumar, K.Sreekumar, C.Sudha Kartha and K.P.Vijayakumar. Solar Energy Materials
and Solar Cells Vol. 94, p. 2212-17 (2010).
89. Effect of precursor medium on structural, electrical and optical properties of sprayed polycrystalline
ZnO films, T.Vimal Kumar, N.Poornima, C.Sudha Kartha and K.P.Vijayakumar. Materials Science
and Engineering B Vol. 175, p. 29-35 (2010).
90. Ex situ Sn diffusion: a well suited technique for enhancing the photovoltaic properties of SnS
absorber layer, T. H. Sajeesh, C. Sudha Kartha, C. Sanjeeviraja, T. Abe, Y. Kashiwaba and K.P.
Vijayakumar. Journal of Physics-D: Applied Physics, Vol.43, p.445102 (2010).
91. Enhancement of electrical conductivity in sprayed ZnO thin film through zero-energy process,
T.V.Vimal Kumar, N.Poornima, C.Sudha Kartha, K.P.Vijayakumar, T.Abe, and Y.Kashiwaba.
Physica-B, Vol. 405, p.4957-60 (2010).
92. Role of precursor solution in controlling the opto-electronic properties of spray pyrolysed
Cu2ZnSnS4 thin films, V.G.Rajeshmon, C.Sudha Kartha, K.P.Vijayakumar, C.Sanjeeviraja, T.Abe and
Y.Kashiwaba. Solar Energy, Vol.85, p. 249-55 (2011).
93. Bias voltage controlled photoluminescence from beta-In2S3 thin films, R.Jayakrishnan, C.Sudha
Kartha and K.P.Vijayakumar. Materials Science in Semiconductor Processing, Vol. 14, p.58-61
(2011).
94. Spray pyrolysed In2S3 Thin films: A potential electron selective layer for large area inverted bulk
heterojunction polymer solar cells, M.R.Rajesh Menon, M.V.Mahesh Kumar, K.Sreekumar, C.Sudha
Kartha and K.P.Vijayakumar. Physics Status Solidi (a), Vol. 209, p.199-203 (2012).
95. CuInS2/In2S3 cells using a cost effective technique: Significance of precursor ratios on cell
parameters, Angel Susan Cherian, T.Abe, Y.Kashiwaba, C.Sudha Kartha and K.P.Vijayakumar.
Energy Procedia, Vol.15, p.283-90 (2012).
96. Composition and conductivity type analysis of spray pyrolysed ZnS thin films, N.Poornima,Anjaly
Jose, C.Sudha Kartha and K.P.Vijayakumar. Energy Procedia, Vol. 15, p. 347 (2012).
97. Band offset of the In2S3/Indium Tin oxide interface measured by X-ray photoelectron spectroscopy,
M.R.Rajesh Menon, A.Mancini, C.Sudha Kartha, K.P.Vijayakumar and A.Santoni. Thin solid Films
Vol. 520, p. 5856-59 (2012).
98. Defect levels in SnS thin films prepared using chemical spray pyrolysis, T.H.Sajeesh, K.B.Jinesh,
Manohar Rao, C. Sudha Kartha and K.P.Vijayakumar. Physica Status Solidi (a) Vol. 109 (7), p.
1274-78 (2012).
99. Role of pH of precursor solution in taming the material properties of spray pyrolysed SnS thin films,
T.H.Sajeesh, K.B.Jinesh, C. Sudha Kartha and K.P.Vijayakumar, Applied Surface Science, Vol.258,
p.6870-75 (2012).
100.Effect of Defect Bands in β- In2S3 Thin Films, R.Jayakrishnan, Tina Sebastian, K.P. Vijayakumar, and
C. Sudha Kartha. Journal of Applied Physics (in press).
101.Double layer CuInS2 absorber using spray pyrolysis: A better candidate for CuInS2/In2S3 thin film
solar cells, Angel Susan Cherian, K.B.Jinesh, Y.Kashiwaba, T.Abe, A.K.Balamurugan, Sitaram Dash,
A.K.Tyagi, C.Sudha Kartha and K.P.Vijayakumar, Solar Energy Vol.86, p.1872 (2012).
102.Determination of thermal and electronic carrier transport properties of SnS thin films using photo
thermal beam deflection technique, Anita R. Warrier, T.H.Sajeesh, C.Sudha Kartha and
K.P.Vijayakumar. Material Research Bulletin Vol. 47, p. 3758-63 (2012).
103.Lattice vibrations of sequentially evaporated CuInSe2 by Raman Microspectrometry, K.G.Deepa,
K.P.Vijayakumar and C.Sudha Kartha, Materials Science in Semiconductor Processing, Vol. 15,
p.120-24 (2012).
104.Modification of optoelectronic properties of sprayed In2S3 thin films by indium diffusion for
application as buffer layer in CZTS based solar cells, V.G.Rajeshmon, N.Poornima, C.Sudha Kartha
and K.P.Vijayakumar. Journal of Alloys and Compounds, Vol. 553, 0p.239-44 (2013).
105.Reliable and damage free estimation of resistivity of ZnO thin films for photovoltaic application
using photo luminescence, N.Poornima,T.V.Vimalkumar, V.G.Rajeshmon, C.Sudha Kartha and
K.P.Vijayakumar. International Journal of Photo Energy, Vol. 2013, article No. 10105796 (2013).
106.Electricity from the Sun: the possibilities. (Popular Article), K.P.Vijayakumar and Angel Susan
Cherian. Energy Manager, Vol.6, p.15 (2013).