Dr. K. R. Justin Thomas

Dr. K. R. Justin Thomas graduated (1990) from The American College at Madurai with a master degree (M.Sc.) in Chemistry. Then he went on to do research in chemistry at Indian Institute of Technology Kanpur with a specialization in inorganic heterocycles. After gaining Ph.D. (1995), he joined the Sophisticated Analytical Instrumentation Facility (SAIF) at IIT Madras to implement a DST sponsored young scientist scheme (1996-1997). After two years stay at IIT Madras he moved to Institute of Chemistry, Academia Sinica, Taipei to take up a post-doctoral assignment. He served five years (1997-2003) as post-doctoral fellow in Taiwan before moving to the Department of Chemistry, University of Massachusetts at Amherst for a year (2003-2004) as research associate. Prior to joining as Assistant Professor at IIT Roorkee in 2006, he again served as senior post-doctoral fellow at Academia Sinica, Taiwan for two years (2004-2006). He is currently serving as Associate Professor of Chemistry from 2012 at the Indian Institute of Technology, Roorkee.

His research work is focused on the development of organic and organometallic dyes suitable for application in electronic devices such as organic light-emitting diodes, dye-sensitized solar cells and bulk-heterojunction solar cells. He has successfully completed six sponsored (DST, CSIR & BASF) projects and two research projects are being implemented. He has published more than hundred research papers (126) in international journals and co-authored five US patents. He has supervised nine PhD thesis and ten MTech dissertations. Currently ten students are registered for PhD under his guidance.

Organic Materials for Electronic Applications

Recent extensive studies have shown that organic materials exhibit a variety of interesting optical, electrical, photoelectric, and magnetic properties in the solid state. Photo- and electro-active organic materials have been the subject of current research, including organic semiconductors, organic metals including superconductors, organic photoconductors, organic photoactive materials for solar cells, organic non-linear optical materials, organic ferromagnets, photo- and electrochromic organic materials, resist materials, liquid crystals, and others. Among them, organic photoconductors, liquid crystals, and resist materials have been put to practical use for photo-receptors in electrophotography, display devices, and lithographic processes for the production of semiconductor devices. In addition, organic materials have found a number of potential applications for use in electronic and optoelectronic devices such as sensors, plastic batteries, solar cells, field-effect transistors (FET), optical data storage, organic electroluminescent devices (OLED), switching devices, frequency doublers, and many others. They can also be used to make optoelectronic devices lightweight, energy-saving, flexible, large area size, low cost, and printable.

Organic electroluminescent devices have recently received a great deal of attention for their application as full-color, flat-panel displays as well as from the unique academic interest. They are attractive because of low voltage driving, high brightness, capability of multicolor emission by the selection of emitting materials and easy fabrication of large-area and thin-film devices.

The materials for organic EL devices should meet the following requirements: (1) to possess a suitable ionization potential and electron affinity for energy level matching for the injection of charge carriers at the interfaces between the electrode/organic material and organic material/organic material, (2) to permit the formation of a uniform film without pinholes, (3) to be morphologically stable, (4) to be thermally stable, (5) to be electrochemically stable, and (6) to be highly luminescent for emitting materials. The development of new materials with high performance and understanding of basic processes, such as charge injection from the electrodes, charge transport, recombination of charge carriers to generate the electronically excited-state molecule, are of vital importance.

Devices for photoelectric conversion using organic materials, which find potential applications as solar cells and photo-sensors, are mainly classified into photoelectrochemical and photovoltaic devices. Photoelectrochemical cells consist of inorganic semiconductors and organic dyes as a sensitizer immersed in an ionically conductive electrolyte containing a redox couple, where light is absorbed by the organic dye. Photovoltaic devices consist of thin films of organic materials sandwiched between two metal electrodes. A built-in electric field, formed in the semiconductor in contact with the electrolyte in the photoelectrochemical cell and in the organic layer at the interface with the metal electrode or with the other organic layer in the photovoltaic device, is responsible for the photogeneration of charge carriers. Improving the quantum efficiency of the photogeneration of charge carriers is a key issue for the development of organic photovoltaic devices with high conversion efficiency.