Functional Materials and their Applications in Devices

Sri Sathya Sai Institute of Higher Learning Department of Chemistry and Physics

Prashanthi Nilayam Campus, Puttaparthi, Andhra Pradesh, 515134 www.sssihl.edu.in

Supported by the

The Indian Academy of Science,

National Academy of Sciences, and

Indian National Academy

CONFERENCE REPORT 26 - 28 OF NOVEMBER, 2015

Functional Materials and their Applications in Devices A brief report of the proceedings

The Department of Chemistry and Department of Physics, of Prashanti Nilayam Campus

jointly organized a three day workshop, titled, “Functional Materials and their Applications in Devices’’ between 26th, 27th & 28th November-2015. The three day workshop was generously supported by the three academy of sciences namely the Indian Academy of Science, National

Academy of Sciences and Indian National Academy.

The program commenced with the inaugural ceremony by invoking the Blessings of the

Almighty in the form of lighting of the auspicious lamp by the honorable chief guest, Prof. K. B. R.

Varma, Vice-Chancellor SSSIHL and Prof Ramasesha, IISc followed by Vedam chanting by the university students. The technical sessions started with Dr. B. Siva Kumar, Asst. Professor, Department of Chemistry, giving the welcome address. He highlighted the importance of functional materials in the present era of materials science. He thanked the three premier national bodies Indian Academy of Sciences, National Academy of Sciences and Indian National Science Academy who played a major role in conducting such in depth conferences at various universities and colleges to promote scientific temper and education in our country. He welcomed all the experts and resource persons from IISc and the students of the University before inviting the Vice-Chancellor for giving the opening remarks.

Prof. K.B.R.Verma, Vice-Chancellor, Sri Sathya

Sai Institute of Higher Learning, commenced his

address by appreciating the efforts put by the three

academies and in specific Prof. Ramasesha who

made this workshop a possibility. He then

mentioned that the three day Workshop on

‘Functional Materials and their Applications in

Devices’ as a visionary leap ahead, in exposing the

nascent minds of tomorrow to the literacy of

modern science.

The area of functional materials is perhaps one of

the fastest growing areas of materials science. Its aims are to tailor materials with desired

functionalities for applications in emerging technologies. It is an area that combines all branches

of science and engineering. The major scientific areas absolutely necessary for tailoring

materials are physics and chemistry of materials which strive to understand the principles that

govern the diverse properties. The aim of this workshop was to introduce the major areas of

applications of materials to students at the master's level. Most of the concepts that the students

are exposed to in their course of study were refocused, extended and applied to obtain an

appreciation of the electronic, optical and electrical processes occurring in the materials used in

devices for energy storage and other emerging electronic applications.

Prof. S. Ramasesha, Professor, SSSCU, Indian Institute of Science, Bangalore delivered the

inaugural address for the workshop.

He stressed upon the primary objective of this

workshop which was to give a sound exposure to the

postgraduate students and research scholars of the

Departments of Chemistry and Physics on the

integrated approach in understanding and solving

scientific problems with practical insights, leading to a

high quality research mind.

The eminent scientists from the IISc, Bangalore were

invited to introduce the major areas of applications of

materials to students at the master's level. Most of the

concepts that the students are exposed to in their course

of study would be refocused, extended and applied to

obtain an appreciation of the electronic, optical and

electrical processes occurring in the materials used in

various devices.

The program involved two lectures each by six scientists working in these areas. Each lecture

was for 75 minutes duration, including discussions. There were four lectures per day. These were

aimed at applying basic concepts to understand electronic transport properties, in materials and

devices and their design strategies.

The reputed experts shared their experience and gave their valuable insights into the nature of

challenges that the society faces in the near future. The specific topics covered are Non-Linear

Properties in Optical Communication, Devices in Energy Storage, Solar Energy Harvesting,

Quantum Mechanics, and Quantum Dots.

The first speaker of the workshop Dr. Anshu Pandey, of Solid

State and Structural Chemistry Unit, IISc., delivered the

lecture on ‘Quantum Dots for electronic applications’. The

talk gave an insight in to the effects of sizes and shapes of

quantum dots on electronic properties. The growing

fascination for nanoparticles and quantum dots was put in

proper perspective by elucidating the electronic properties of the two. 3D confined electron wave

functions in a quantum dot was introduced, and a parallel was drawn to the wave function of a

particle in a box. Splitting of energy levels for small quantum dots due to the quantum

confinement effect was also described. He explained their applications in various fields with the

example of Cadmium Selenide quantum dots. The applications varied from biological, to

industrial, optical, and consumer electronics industries, was justified, from their properties.

The second lecture was commenced at 11.00 am by

Prof. Satish Patil, Solid State and Structural

Chemistry Unit, IISc., on the theme ‘Organic

materials for electronic devices’. His talk

comprised of understanding the concept of

polymers, conductive polymers and their properties

for the beginners. He discussed the various routes of

synthesizing the polymers and examples of

condensation reactions. The speaker elucidated the

practical usage of the polymers, where, most of them are doped oxidatively to give p-type

materials. The redox doping of organic conductors is analogous to the doping of silicon

semiconductors, whereby a small fraction of silicon atoms are replaced by electron-rich, e.g.,

phosphorus, or electron-poor, e.g., boron, atoms to create n-type and p-type semiconductors,

respectively.

The first technical session of the workshop closed with summary of the presentations followed

by Lunch.

The second session was started at 1.30 pm. The first speaker

of this session was again, Prof. Satish Patil, who continued

his lecture on the earlier theme and explained the strategies in

tailoring of organic molecules for applications in electronic

devices. The speaker suggested that, conducting polymers are

also promising in organic solar cells, printing electronic

circuits, organic light-emitting diodes, actuators,

supercapacitors, chemical sensors and biosensors, flexible transparent displays, electromagnetic

shielding and possibly replacement for the popular transparent conductor indium tin oxide. Most

recent emphasis of these materials, on organic light emitting diodes and organic polymer solar

cells was discussed. He cogently related the conduction band theory and the molecular orbital

theory in to one.

In his second lecture, Dr. Anshu Pandey presented his

work on quantum dots, their composition and properties. He

elucidated the optical properties of quantum dots with a

special focus on gold quantum dots and the overpowering

nature of quantum dots over nanomaterials. To explain in

detail the cause of the bright fluorescence, shown by

quantum dots, the model of electrons and holes was invoked. In a simplified model, the energy

of the emitted photon was understood as the sum of the band gap energy between the highest

occupied level and the lowest unoccupied energy level, the confinement energies of the hole and

the excited electron, and the bound energy of the exciton (the electron-hole pair). Furthermore, it

was shown that the lifetime of fluorescence is determined by the size of the quantum dot. Larger

dots have more closely spaced energy levels in which the electron-hole pair can be trapped.

Therefore, electron-hole pairs in larger dots live longer causing larger dots to show a longer

lifetime. On a concluding note of the talk, the environmental impact of bulk manufacturing and

consumption of quantum dots, currently undergoing studies in both private and public labs, was

also explained.

The first day of the workshop was concluded with summary presentations followed by tea at 4.15

pm.

The Day 2 of the Workshop commenced at 9:00 am.

The first speaker for the 3rd

session was Professor S. Ramasesha, Solid State

and Structural Chemistry Unit, IISc. He started the discussion by explaining the

electronic states of a hydrogen atom. Using this as the background, Prof.

Ramasesha extended the discussion to a multi electron system. He also

elaborated on how the electronic bands in the material arise and the

interpretation by a physicist and chemist of these bands. He also explained an

intermediate view of this concept by invoking the concept of the density of the

states. Then based on these inputs, he explained as to how the electrical

properties are conferred on to a material. He also gave brief explanation of

Peierl’s instability and its implications. He concluded the talk explaining

effective mass and its importance in the quantum calculations. The talk was

insightful which dissolved the boundaries between seemingly different Quantum Chemistry and

Quantum Mechanics.

His talk was followed by Professor A.K.

Shukla, Solid State and Structural Chemistry

Unit, IISc at 11.00 am. His lecture was on the

topic ‘Materials for energy storage- Batteries

and Super-capacitors’. In the introduction

Prof. Shukla, explained all the terminology

like energy density, specific energy, power

density etc. with appropriate formulae which

are needed to understand the nuances of the

energy storage devices. He explained the

functioning of Lead-Acid battery from the practical point of view and the challenges involved in

improving its efficiency. He then explained about the next generation energy devices which

include lithium ion batteries, sodium batteries etc. He then discussed the challenges involved in

the use of lithium ion batteries due to its poor temperature tolerance. The rising demand for

better energy harvesting and energy storage were highlighted in his talk.

The 3rd session was closed with the summary of the presentations.

The 4th session was commenced after lunch at

1.30 pm by Professor P.K. Das, Inorganic and

Physical Chemistry Department, IISc. He gave

an insightful talk on Non Linear Optical

Properties of Organic molecules in

communication. Prof. Das spoke about how the

nonlinear properties of a material arise and how

it can be tuned by minor structural changes of

the molecule so as to improvise its efficiency.

He briefed about different types of dipole

moments and their effect on the properties of the material. He also outlined the importance of

theoretical studies of these properties in order to understand the behavior of the materials. The

speaker also gave numerous examples of molecules across various classes of materials to make

the understanding better. The talk outlined on the necessary properties of organic molecules with

high NLO properties and effect of various electron pumping and withdrawing functional groups.

The last speaker of the morning session was Dr. Sheela, K.

Ramasesha, IISc. She expressed her view on the current

dependence of society on Non-renewable resources and the

deficiency of these resources in future. She emphasized the need

to turn to Renewable resources with the prime focus on Solar

Energy Harvesting. She succinctly put various concepts like

angle of inclination in setting up of solar panels and their

maintenance. She also explained different types of solar panels

along with their efficiencies and applications. In addition to this

she also described about the innovative projects that their group

has undertaken in different fields including those of installing

solar panels on the roof of fast moving trains. She also explained

about their experimental project in IISc campus and their success in providing solar energy to

some of their buildings. She concluded her talk by impressing on the audience, the importance of

harvesting solar energy in a developing country like ours in order to lead a sustainable and

healthy living.

Day 2 ended with the summary presentations.

The Day 3 of the work shop on Functional

material and their applications in Devices

commenced at 9.00am. The first speaker

was Professor A.K. Shukla and he

expressed the outlook of modern scientific

society at future energy storage devices. The

aim for higher power density and current

density kept the research on in this field.

The talk focused on the problems associated

with the research of lead acid batteries, and

ways to overcome them. Some of the

methods to do so were to combine them with supercapacitors, so as to get high charge density,

along with the power density the acid battery provides. A real life application of these in

developed countries, was seen and it was concluded as a success story. The speaker explained

the pioneering work his group is embarking on to improve the technology and make it more

suitable to the Indian roads. I was glad to hear that the first prototype was in the making, and it

may soon be a reality.

The second speaker of the 5th

session was

Dr. Sheela, K. Ramasesha continued on

the topic of Solar Energy Harvesting. She

explained the type of semiconductors used

in the construction of solar panels and

trackers used. Dr.Sheela, along with her

team from MESHA energy solutions pvt.

Ltd. demonstrated the applicability of solar

light that are being manufactured. She also

explained about their trial projects across

India and shared the feedback from the

customers. The session was quite interactive and it was closed with the felicitation of Dr. Sheela

Ramasesha.

The last session of the workshop was commenced at 1.30 pm with the first talk by Professor

P.K. Das. Second harmonic generation, a nonlinear optical process, in which photons with the

same frequency interacting with a nonlinear material are effectively "combined" to generate new

photons with twice the energy, and therefore twice the frequency and half the wavelength of the

initial photons was the topic of discussion. The speaker dwelled on second harmonic generation,

as an even-order nonlinear optical effect, which is only allowed in media without inversion

symmetry. It is a special case of sum frequency generation.

Generating the second harmonic, often called frequency

doubling, and its application in radio communication was seen.

It is a special case of frequency multiplication. An electron

being pushed side-to-side by a sinusoidal-oscillating force, i.e.

the light's electric field. But because the electron is in an

anharmonic potential energy environment, the electron motion

is not sinusoidal. He also dwelled up on the interesting aspects

of nanoparticles and their Non Liner Properties. His talk

included the optical properties of one dimensional organic

molecules with conjugation. He was duly felicitated at the end

of his talk.

The last speaker of the workshop was again the key personality involved in organizing this

workshop, Professor S. Ramasesha who gave the snippets of

quantum chemistry and explained the Schrödinger equation

and perspectives of certain physical terms from chemistry and

physics point of view. He gave an understanding of the

materials both in terms of the Molecular Orbital Theory

(MOT) as well as the Energy Band Theory. He also explained

the shortcomings of the Energy Band Theory. He briefed

about the Mott transition involving the Metal-Insulator

transition brought about by applying the pressure. Discussion

involving the Hubbard parameter was quite insightful. Prof.

Ramasesha concluded his talk by explaining the mechanisms

of electrical conduction in the polymers.

The workshop was ended with the question and answer session. Prof. Ramasesha was duly

felicitated by the Vice Chancellor KBR. Varma for organizing a fruitful workshop at SSSIHL.

Prof. G. Nageswara Rao, Head of the

Department of Chemistry, proposed vote of

thanks on behalf of the organizing committee.

The workshop has lifted up the boundaries

between Chemistry, Physics, and Material

Science.

The students from Dept. of Chemistry and Dept. of Physics

expressed their views on the workshop and how it added value

to their intellectual property. There was a photography session

in the end.

The workshop was concluded by offering our gratitude to Bhagwan Sri Sathya Sai Baba, the

Founder Chancellor of the Sri Sathya Sai Institute of Higher Learning, for making this workshop

a grand success.

GLIMPSES

Felicitation of the esteemed scientist by the Vice-Chancellor and senior

professors of SSSIHL

The group photo with speakers, professors

and students