VISIT AT INUP IIT BOMBAY

Mr. Sumit Kumar, Assistant Professor, ECE Department, Dronacharya College of Engineering visited IIT Bombay for twelve days to execute the sanctioned project work from 27th June - 9th July 2016 as a Principle Investigator (PI). The project titled “Design and Development of a Highly Efficient Graphene Based Photovoltaic Device”. The project proposal is shortlisted under INUP Programme of IIT Bombay (Indian Nanoelectronics Users Programme) which is duly funded by DeitY (Department of Electronics & Information Technology), MCIT (Ministry of Communication and Information Technology) Government of India. Indian Nanoelectronics Users Program (INUP) is a unique activity jointly run by the CEN (Centre of Excellence in Nanoelectronics) at the Indian Institute of Technology, Bombay (IITB).

The whole work was progressed in the Organic Electronics Lab, Bio-sensors, characterization & NCPRE (National Centre for Photovoltaic Research and Education) Labs of CEN, IIT Bombay and divided into two slots. In the first slot, ITO coated glass substrates were cut into desired sizes from the bulk with the help of diamond cutter and later series of steps were taken to make them viable for the device fabrication under different configurations. In first step substrates were cleaned with acetone & later with 2-propanaol solution under sonication process. Then, samples were placed in Plasma Asher to further clean the unwanted impurities from the surface of substrates before the fabrication of device. Later, samples were coated with PEDOT: PSS material for creating HTL (Hole Transport Layer) layer with the help of spin coater & annealing was done for 5 mins at 2000 C using hotplate.

Spin Coater Specifications: -

1. Speed – 2000rpm

2. Acceleration/Sec – 800 acc./sec

3. Time - 60sec

Simultaneously, composite materials for active layer deposition on the substrate with different concentrations & configurations were prepared (in one day advance) & sonicated with the help of sonicator. The materials used for active layer deposition were MEHPPV & P3HT (both are conducting Polymers & as it is procured from Sigma Aldrich), GO & rGO, & TiO2. The blends were prepared using solvent mixing technique. The whole set up for the different activities was coordinated with the system mentor & PhD scholars of IIT Bombay to meet the safety requirements of the sophisticated laboratories. TiO2 NPs & rGO NPs were mixed in different proportions with polymer MEHPPV & P3HT in order to obtain the efficient hybrid complex. After the deposition of active layer on to the devices for (BHJ) Bulk Hetro Junction structures, the devices were then placed in Thermal Evaporation Unit to fabricate the Al as a back electrode for the collection of electrons. A thickness of 100nm using Al was obtained using the technique which is sufficient for the purpose. In second slot, the devices were characterised for various electrical tests with the help of NOVA simulator of NCPRE lab to study the following parameters –

1. Open circuit voltage (Voc)

2. Short circuit current (Isc)

3. Sheet resistance (Rs)

4. Shunt Resistance (Rsh)

5. Maximum current (Imax)

6. Maximum voltage (Vmax)

7. Dark current studies (Id)

8. Light current studies (Iph)

9. Fill factor (FF)

10. Efficiency (n)

Similar tests were performed on the other fabricated substrates of various configurations & varying concentrations of above said materials were characterised to obtain the optimised properties of modified materials for above mentioned parameters. Some serious issues were observed during the fabrication of devices which hinders the performance of prototype OPV cell & leads to an in - efficient device. All the cases are under consideration & their remedies will be implemented in next visit only after the due discussion with Scientists & Professors of the field from ISM Dhanbad, CSIR - NPL New Delhi & IIT Delhi.

The visit helped in learning new concepts & motivated a lot to move further in the field of innovation & creativity.

Some Glimpses: