This is the Proceedings of ECS Symposium on Photovoltaics for the 21st Century, held in October 2009 in Vienna. The Symposium received over 50 invited and contributed papers. These papers cover major solar cell technologies, from silicon to thin films to 3rd-generation. Material synthesis and characterization, cell fabrication, and device physics and testing for various solar cell technologies are reported.

"Presentations of the 'Symposium on Photovoltaics for the 21st Century II' ... part of the 199th Meeting of the Electrochemical Society held in Washington, D.C. in March 2001"--Pref.

The papers included in this issue of ECS Transactions were originally presented in the symposium ¿Photovoltaics for the 21st Century 6 ¿, held during the 218th meeting of The Electrochemical Society, in Las Vegas, Nevada from October 10 to 15, 2010.

Energy may be the most important factor that will influence the shape of society in the 21st century. The cost and availability of energy significantly impacts our quality of life and the health of national economies. This book examines the energy sources that play a vital role in society.