A New Invention in Manufacturing of Solar Cells

Scientists at Gujarat Energy Research and Management Institute (GERMI), Gandhinagar, Gujarat in collaboration with researchers from Pandit Deendayal Petroleum University (PDPU), Gandhinagar and CSIR-Central Electronics Engineering Research Institute (CEERI, a laboratory of the Council of Scientific and Industrial Research, Govt. of India), Pilani have demonstrated a model-based calculation of the effect of indium composition on the open-circuit voltages of indium-gallium nitride (InGaN) Schottky junction solar cell (SJSC) under monochromatic light illumination. InGaN is a very novel semiconductor material system, which has the potential to achieve solar cell efficiencies of over 50 % in comparison to the present efficiency of 7.12 %. By changing the indium and gallium fractional composition in InGaN, the band gap of this semiconductor can be adjusted to span 90 % of the solar spectrum in comparison to a fixed band gap solar cell, thus efficiently converting photons of different energy into electricity. The current world record efficiency for solar cells is 43.5 %, which is achieved by researchers at Japan. InGaN is already being used commercially for bright light-emitting diodes (LEDs), and now researchers worldwide are exploring into InGaN for solar cell applications.

On the other hand, SJSC is the simplest of all the existing solar cells, which consists of metal-semiconductor junction exposed to the incident sunlight. In the present work, four different metals namely, gold, palladium, nickel and platinum were used to make Schottky contacts with n-InGaN semiconductor. The open-circuit voltages have been calculated using the analytical model (This analytical model is developed by the same scientists and already published in Journal of Electron Devices, an international peer-reviewed journal) and computer-based simulations. Among four systems, Pt/ n-InGaN/ Al system resulted in the highest open-circuit voltage, due to the catalytic property of platinum, which helps in reducing the surface recombination at the Schottky interface. Now-a-days, model-based studies are important to explore the details of the devices before carrying out the practical experiments.  

The output of the research is recently published in American Institute of Physics Conference Proceedings Journal (view online: http://dx.doi.org/10.1063/1.4732375) authored by Pramila Mahala, Sanjay Kumar Behura, Abhijit Ray, Chenna Dhanavantri and Omkar Jani.


Figure: InGaN solar cell device structure used for the simulation.