Department of Physics, Engineering Physics & Astronomy

Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

It's All About Growth: Mixed Phases Protocrystalline Silicon Solar Cells

Dr. Joshua M. Pearce
Queen's University - Mechanical and Materials Engineering

Wednesday, October 1, 2008
3:30 PM @ Stirling A

Abstract:

A sustainable energy system must be developed that can both mitigate climate change by reducing the growth of greenhouse gas emissions while meeting the growing global energy demand. Solar photovoltaic (PV) electrical production is technologically feasible and a clean environmentally-benign solution to society's future energy requirements and the solar industry is growing explosively, but its costs must continue to decline to be economically competitive with fossil fuels.

Protocrystalline silicon based solar cells offer this possibility as witnessed by the enormous influx of industry investment, although there are still technical questions to be answered concerning the light induced degradation of its electronic properties known as the Staebler-Wronski Effect (SWE). Numerous theories have been proposed to explain (and thus control) SWE, but they have for the most part failed. Recently, the contributions of multiple defect states to the SWE kinetics were identified and quantified for the first time. Utilizing AFM, TEM, and real time spectroscopic ellipsometry to track the growing phase of Si:H, the evolutionary nature (protocrystallinity) and substrate dependence of its growth were established. This work in using phase diagrams to guide the growth of protocrystalline materials have both improved the light I-V characteristics on solar cells and the understanding of the nature of the multiple light-induced defect states responsible for SWE. By applying this knowledge of both microstructure and recombination Si:H solar cell performance can be improved to assist our growing society move towards a sustainable energy system.

Refreshments will be served 15 mins before the talk.