Bachelor of Science (B.Sc.) in Physics 1997-2000 University of Kerala

Master of Science (M.Sc.) in Physics 2000-2002 University of Kerala

Doctor of Philosophy (Ph.D) 2009 Cochin University of Science and Technology

Bachelor of Science in Physics (98.2%), Rank Holder, Kerala University

CSIR-SRF 2007

INSA Teacher Summer Research Fellowship 2010

INSA Teacher Summer Research Fellowship 2012

Technical Officer at HIND HIGH VACUUM COMPANY PVT LTD, Bangalore 2008

Senior Executive at TATA BP SOLAR INDIA LTD, Bangalore 2008-2009

Assistant Professor in Physics at Christian College Changannur 2009-2020

Photo-conduction Mechanisms
Photovoltaic Device structures
Clean Water & Energy
Smart Materials, Devices and Structures for Artificial Intelligence
Photo-luminescence
Space Age Materials & Technologies
Surface Photo voltage Phenomenon

1. Recipient of Kerala State Young Scientist Award 2015 from Kerala State Council for Science, Technology and Environment, Govt. of Kerala.
2. Melpadom Attumalil Gerogekutty Young Scientist Award 2019 from the MALANKARA MAR THOMA CHRUCH OF INDIA
3. Certificate Award “Outstanding contribution in Reviewing” for the journal of Sensors & Actuators: B Chemical (Elsevier, The Netherlands) June 2017
4. Nominated by the Kerala State Government for the Bhaskara Adavanced Solar Energy fellowship


Consultancy Projects Completed

Computerization of Hospital Service for the The District Cooperative Hospital, Pathanamthitta
Digital banking solution for the banking services for The Government Servants Cooperative Society, Pandalam
Digitization and Core banking solution for the banking services for the The Government Servants Cooperative Bank, Kulanada
Core banking solution implementation for the The Service Cooperative Bank, Keezhvaipour
Trail on anti-scratch coatings for ornaments for Dharmaj Technologies, Surat.

Patents
1. Indian Patent Application No: 2341/CHE/2009

Patent request application submitted for filling to Department of Science and Technology vide letter KSCSTE letter No. 037/PF-PIC/2017/KSCSTE on “SILAR grown conducting Copper Zinc Tin Sulphide thin films”
Patent request application submitted for filling to Department of Science and Technology vide letter No.001/PF-PIC/2017/KSCSTE of KSCSTE on “Spray coated absorbing and conducting Copper Sulphide thin films”

1. Structural, magnetic, optical, and photoresponse studies of hydrothermally prepared nanocrystalline GaxFe2-xO3 (x=0.7, 1 & 1.3) Materials Chemistry and Physics (Article in Press)

2. Efficacy in degradation of carcinogenic pollutant Sulforhodamine B by green synthesized Silver Nanoparticles, Ramakrishnan Jayakrishnan, Anju Joseph, Vinoy Thomas, Micro and Nano letters (Article in Press)

3. Direct Sunlight Driven In2S3 Thin film based Water Treatment Proto-type, R. Jayakrishnan, Journal of Water Chemistry and Technology (Article in Press)

4. Copper Doped Cesium Lead Bromide colloidal Nano-platelets, R Jayakrishnan, Ramesh Chandran, Aruna R Raj and Sreekanth J Varma, Journal of Nanoparticle Research 23(9), 210 (2021) https://doi.org/10.1007/s11051-021-05324z

5. DSSC using Wrightia tinctoria (Roxb.) R Br.: A TRIAL, Materials Today: Proceedings 2021, https://doi.org/10.1016/j.matpr.2021.07.423

6. Self-assembled methyl-ammonium lead bromide thin films with blue photoluminescence R. Jayakrishnan, Aruna Raj, Sreekanth J Varma, Applied Nanoscience (2021) https://doi.org/10.1007/s13204-021-01933-1

7. Water and Nutrient Recovery from Urine: A Lead up Trail using Nano-structured In2S3 Photo electrodes, R. Jayakrishnan, Sreerev T. R, Adith Varma, CHINESE PHYSICS B, Vol. 30, No. 5 (2021) 056103 https://doi.org/10.1088/1674-1056/abd169

8. Near-white light emission from samarium and dysprosium combined doped calcium zirconate spin-coated thick film, Venugopal M, Padma kumar H, Jayakrishnan R, Bulletin of Materials Science, 44(2) (2021)

9. Tunable blue-yellow and orange-red emissions from Dysprosium and Samarium doped SrCeO3 perovskite systems, M Venugopal, HP Kumar, R Jayakrishnan, Journal of Solid State Chemistry 296, 121975 (2021)

10. Deposition of CZTS/ZnO heterojunction using SILAR and Spray Pyrolysis, R. Jayakrishnan, Aruna Raj, Varun G Nair, SEMICONDOCTORS, 2021, Vol. 55, No. 3, pp. 363–372

Journal Publications 2020:

1. Anomalous photoconductivity in chemical spray pyrolysis deposited nano-crystalline ZnO thin films, Varun G.Nair, R. Jayakrishnan, Jancy John, Jishad A.Salam, Akhil M. Anand , Aruna Raj, Materials Chemistry and Physics, 247, 122849 (2020)

2. Effect of annealing temperature on the photoluminescent properties of nanocrystalline CaZr0.9SmxDy0.1-xO3 systems prepared via self- propagating combustion Synthesis, Meenu Venugopal, Hariharan Padma Kumar, Ramakrishnan Jayakrishnan, Physics Letters A, 22126280 (2020) https://doi.org/10.1016/j.physleta.2020.126280

3. Flexible CuO-ZnO Nano-Bulk junction with photovoltaic response, R Jayakrishnan, Akhil M Anand and Varun G Nair ,Materials Research express 6,1250d9 (2020)

4. Polymer encapsulation as an effective method for enhanced stability in perovskite quantum dots, Aruna Raj, R. Jayakrishnan, and Sreekanth J. Varma AIP Conference Proceedings 2265, 030148 (2020); https://doi.org/10.1063/5.0017119

5. J V analysis of a bulk-nano junction grown on flexible substrate, Varun G. Nair, Akhil M. Anand, and R. Jayakrishnan AIP Conference Proceedings 2265, 030477 (2020); https://doi.org/10.1063/5.0016665

Journal Publication list

1.A LEAD UP TRIAL ON RECYCLING OF URINE, R. Jayakrishnan and Sreerev T R, International Conference on Advanced Innovation in science, Engineering & Technology (ICAISET-2019) 8th November 2019, organized by Sree Ayyappa College, Eramallikkara, Kerala, and Techown

2.Flexible CuO-ZnO Nano-Bulk junction with photovoltaic response, R. Jayakrishnan, Akhil M Anand and Varun G Nair, Proceedings of the International Conference on Photochemistry and Sustainable Energy ICPSE 2019 , St. Michael’s College, Cherthala, Alappuzha, Kerala

3.Photo catalytic behavior of green synthesized Ag Nano-particle, . Jayakrishnan, Anju Joseph, Varun G Nair and Rani Abraham, Proceedings of the International Conference on Advances in Sustainability of Materials and Environment (ICASME’19), 4th and 5th of April 2019, St. Xavier’s Catholic College of Engineering, Chunkankadai, Nagercoil, India.

4.Luminescent, Polymer Encpasulated Organolead Halide Perovskite Quantum Dots for Optoelectronic Applications, Aruna Raj, Manju V, R Jayakrishnan, Sreekanth J.Varma Proceedings of the International Conference on Optical and Advanced Materials, Cochin University of Science and Technology, 2019

5.Photoluminescence of SILAR grown Cu2ZnSnS4 thin films , R Jayakrishnan, Anusree Rajan, Akhil M Anand, Meera Venugopal, Varun G Nair, DilnaGopinath and Adithya M V. Proceedings of the International conference on spectroscopy of Bio-molecules and Advanced materials (ICBAMS 2017), Pg No. 53 ( 2017)

6.Effect of annealing on the Photoluminescence from SILAR grown ZnO thin films, , R Jayakrishnan, Adithya M V, Akhil M Anand, MeeraVenugopal, Varun G Nair, Dilna Gopinath and Anusree Rajan, Proceedings of the International conference on spectroscopy of Bio-molecules and Advanced materials (ICBAMS 2017), Pg No. 122 ( 2017)

7.Can a Silver Plasmonic Layer alter the performance of a Cu2O/In2S3 thin film Solar Cell ? R. Jayakrishnan, Rani Abraham and Manivarnan, 26th PVSEC, NUS, Singapore, October 25-28, 2016.

8.Effects of surface texurization of In2S3 window layer in the Cu2O/In2S3 Solar cell, R. Jayakrishnan and Varun G Nair, International conference on Electrical, Electronics and Optimization Techniques (ICEEOT 2016), DMI College of Engineering, Chennai, Tamilnadu, 3-5 March 2016, Pages: 3770 – 3772 10.1109/ICEEOT.2016.7755417

9.Si- wafer minority carrier lifetime analysis for performance estimation, Shreyans Gandhi and R. Jayakrishnan, International Conference on Nanoscience and Technology, ICONSAT, IIT Bombay, 16-18 February 2009.

10.Role of intermediate bands of sprayed β- In2 S3 in sprayed CuInS2/In2S3 Solar cells, R. Jayakrishnan, Teny Theresa John, C.Sudha Kartha and K. P.Vijayakumar Proceedings of the International Conference on Solar Cells (IC-SOLACE), 21-23 Jan 2008, Cochin. p. 188

11.Temperature and Temporal dependence of Photosensitivity of β- In2 S3 thin films under sub band gap excitation of 2.33 eV. R. Jayakrishnan, Teny Theresa John, C.Sudha Kartha and K.P.Vijayakumar International Conference on Materials for Advanced Technologies, Symposium J: Materials for Advanced Sensors and Detectors,1–6 July 2007, Singapore.

12.Comparative study of Cu rich and In rich CuInS2 Thin Films prepared Using Automated Spray System. Tina Sebastian, Teny Theresa John, R. Jayakrishnan, K. P. Vijayakumar, C.Sudha Kartha, Deepthi Jain and V. Ganeshan. International Conference on Optoelectronic Materials and Thin Films OMTAT-2005, 24-26th October 2005, Cochin, India. 13.Room Temperature Photoluminescence Surface Mapping R. Jayakrishnan, Tina Sebastian, C.Sudha Kartha and K.P.VijayakumarInternational Conference on Materials for Advanced Technologies, Symposium Y: Optical Spectroscopic Techniques, 3–8 July 2005, Singapore.

Current Trends in Materials Science – 2011 Special Volume of IOP Conference Series: Material Science and Engineering: Editors: R. Jayakrishnan, U. V. Unnikrishnan and K. P. Vijayakumar 2013 IOP Conf. Ser.: Mater. Sci. Eng. 43 011001 doi:10.1088/1757-899X/43/1/011001

Photoconductivity for Beginners , LAP LAMBERT Academic Publishing, May 2012. ISBN-13: 9783659106033.

Clean & Green Technology for Water purification

Under the Climate Resilient Scheme of the Directorate of Environment and Climate Change this project is ongoing with an objective to develop a prototype device that could recycle waste water. Uploaded on : 2020-06-14

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Fabrication of Pb free Perovskite solar cell

Under the Kerala State Young Scientist Award this project is on going with an objective to solution process a Lead free perovskite solar cell.
Uploaded on : 2020-06-14

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Bulk-nano junctions for photovoltaic device applications


Ø Growth of photovoltaic devices exhibiting quantum confinement effect achieved.
Ø Mapping of the surface in-homogeneity based on Scanning Kelvin Probe Microscopy demonstrated.
Ø Probed into the fundamental property like Carrier lifetime, Mobility, Work function and diffusion coefficient.
Ø Identified quantized levels using low temperature current-voltage studies.
Uploaded on : 2020-06-14

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Effects of Size Quantization on Solar cells


• Developed Cu/Cu2O@nano/In2S3@nano Solar cells.
• Investigated surface potential distribution in bulk nano junction.
• Investigated resonant tunneling peaks in bulk- nano junction.
• Measured absolute work function and ionization potential.
• Access the density of states (DOS) information.

Uploaded on : 2020-06-14

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Investigation on the Cu2O/In2S3 Solar cells using Scanning Tunneling Microscopy

An injection chemical vapor deposition (ICVD) was indigenously developed. The system consists of a two zone furnace, a substrate holder and an atomizer. An airbrush with 0.25 mm nozzle serves as the atomizer which is connected to a compressor capable of delivering maximum pressure of 300 psi. The airbrush contains a gravity fed tank to store the precursor solution. The temperatures in zone 1 and zone 2 can be controlled using partial integrator differentiator controllers. The maximum range of temperatures for zone 1 and zone 2 are 400 0C and 600 0C respectively.

Using annealing process of the Copper substrate the principal investigator has developed two recipes that can be used to grow Cu2O thin films on Cu substrate. Off the two recipes it was found that annealing at higher temperature was more suited for growing ploy crystalline Cu2O thin films. This was also evident from the scanning electron micrograph (SEM) of the Cu2O layer obtained by oxidizing the copper substrate. The grains of Cu2O are in-homogenously spread over the substrate and the existence of voids was evident from the SEM analysis. It was clear from the SEM images that the heat treatment had not lead to growth of completely crystallized Cu2O grains all over the Cu substrate. We hence concluded that the number of Cu2O grains grown on Cu substrate was small.

Nano In2S3 was deposited on to the Cu/Cu2O structure using injection chemical vapor deposition (ICVD) technique. Precursor solution of 25 ml containing a mixture of 0.2M Indium chloride and 1M Thiourea was atomized to obtain a ~300 nm thick layer of nano-crystalline In2S3 on to the Cu2O layer. Another layer of In2S3 was grown over this layer with the airbrush being replaced with a spray gun having a nozzle of size 1 mm. Precursor solution of 50 ml containing a mixture of 1.2M Indium chloride and 8M Thiourea was atomized to obtain a ~800 nm thick layer of In2S3. Four Ag electrodes each of 2 mm2 area were deposited on In2S3 layer which were interconnected by dry soldering single strand Ag wires. The hetero-structure Cu/Cu2O/Nano@In2S3/In2S3/Ag fabricated is hereafter called as the “quantum confined solar cell”.

STM measurements were carried out in a configuration such that carriers injected from the tip into the In2S3 contact layer have to undergo transport into and through the entire device structure to contribute to the overall current measured at the Cu collector contact.

STM images show that there are crystallite aggregates composed of micro-crystallites of diameter of about 20 nm. The STM image provides contrast at the background which may be the tissue of the underlying n-type In2S3 layer. While not resolving the inner crystallite structure of the columns, it is evident that they are encapsulated by a different material, which can be attributed to a disordered tissue that forms a continuous geometrical, and thus a possible conducting, percolation network. Our STM measuremetns lead us to conclude that “As there are highly insulating grains with a substantial potential barrier at the In2S3/Cu2O interface, separated by grain boundaries with higher conductance and locally reduced contact barrier, carriers injected into the In2S3 layer above a grain may spread over the In2S3 to the surrounding grain boundaries, where they are transferred into the p-Cu2O absorber and to the STM collector contact.”

Uploaded on : 2020-06-14