[1] Univ Calif Merced, Dept Phys, Merced, CA 95343 USA
[2] NASA, Univ Space Res Assoc, Cleveland, OH 44135 USA
[3] NASA, John H Glenn Res Ctr, Photovolta & Electrochem Syst Branch, Cleveland, OH 44135 USA
[4] Natl Renewable Energy Lab, Mat Chem & Computat Sci Directorate, Golden, CO 80401 USA
[5] Wilberforce Univ, Dept Chem, Wilberforce, OH 45384 USA