Electrodeposition of Photoactive Silicon Films for Low-Cost Solar Cells

Here we demonstrate progress on electrodeposition of photoactive silicon films from an environmentally friendly molten CaCl2 electrolyte, which is the first step of a new route to a practical low-cost silicon solar cell. We report electrodeposition of several-micron thick silicon films on a graphite substrate in a bath of molten CaCl2 containing SiO2 nanoparticles. The best silicon deposits was obtained at 6 mA/cm2 for 1 hour in molten CaCl2 containing 0.3 M SiO2 nanoparticles, at 850°C. The main impurities are Al, Mg, Ca, Na. A photoelectrochemical method was demonstrated as a reliable and sensitive measurement for testing the quality of the silicon film. The as-deposited film exhibits 31% of the photocurrent response of a commercial p-type wafer. A comparison of graphite and silver substrates is presented, and the remaining problems are discussed.