Research

Our laboratory is geared for studies which help us in understanding the electronic and optoelectronic processes in extended macromolecular systems. We then utilize this knowledge for device development; specifically solar cells and field effect transistors. Besides this, we dabble in bioelectronics where we explore these soft-electronic polymers for biophysical problems and utilize it in tissue engineering and for vision prosthetic elements.

Techniques

Tailor-made, custom-designed experimental methods to probe characteristic responses, time scales and length scales is pursued routinely. For example: we have come up with imaging methods to examine the heterogeneity in photoconducting polymer blends from 10 nm to several micron length scales. The notable thing is that we have the capability to zoom in on a stationery sample from confocal microscopy length scales to Atomic Force Microscope scales. This utilizes a combination of tips: including glass aperture tips for near field access and convention AFM tips. So if the sample has contrast features arising from optical/dielectric/topological/…. at these length scales, we get interested and analyze and see if there are correlations with bulk properties

We also extensively use noise measurements to probe the fluctuations in electrical transport which are inherent in these disordered systems. The novelty of this approach is that we are able to carry out noise measurements under constant photoexcitations. The fluctuations in the current with steady state of pumping carriers in the system directly reveals the trap kinetics, and importantly it reveals the condition of a photovoltaic module.
We carry out switching studies to examine the speed and the limitations of Field effect transistors over a frequency range extending up to100 MHz. Yes ! organic FETs have response beyond 1 MHz, we are now able to operate these FETs and make basic circuits in the MHz regime.

Bioelectronics

Soft-electronic polymers in biomedical arena exhibit utility in tissue engineering and for vision prosthetic elements. We examine many aspects of this important research topic, For example, recent research breakthrough from our laboratory in the area of interfacing organic-electronic with visual systems, specifically “Organic optoelectronic structures as artificial visual elements for a blind retina”.

Interfacing biological systems with electronic components augments the possibility of repairing and restoring various physiological processes. In recent studies, the efficacy of polymer semiconductors as artificial receptors for interfacing with the visual systems was highlighted. We now have extensive interaction with biophysicists, electrical engineers, neurophysiologists, and ophthalmologists to translate some of our preliminary lab demos to more indepth in-vitro and in-vivo studies. And hope to bring a polymer-retina as an option for visual-retinal disorders

Materials

Design and characterising new organic electronic materials forms a major part of our activity. We actively collaborate with leading chemists in this field and provide feedback in the quest for developing high mobility polymers and small molecules, acceptor molecules for bulk heterojunction based solar cells, high and low-k dielectrics. We spent considerable effort in optimizing processing conditions for a desired property. Processing tools include spin-coating and printing methods, annealing under electric field conditions, soft-lithography approaches, vapor deposition….

Devices

Range of photovoltaics structures and architecture have been studied in our laboratory. We specifically are interested in developing large-area devices with low manufacturing complexity.

The laboratory has pioneered in developing polymer based optical-field effect transistors, Interfacing Organic/polymer Semiconductors with Biological Media at molecular-cellular-system level, large-area position sensors, stretchable-flexible light emitting diodes, resonant cavity NIR high speed detectors, large organic solar cell designs

Research