Optimal structures for high efficiency thin film silicon solar energy conversion devices and systems are disclosed. Thin film silicon active layer photoelectron conversion structures using ion implantation are disclosed. Thin film semiconductor devices optimized for exploiting the high energy and ultraviolet portion of the solar spectrum at the earths surface are also disclosed. Solar cell fabrication using high oxygen concentration single crystal silicon substrates formed using in preference the CZ method are used advantageously. Furthermore, the present invention discloses optical coatings for advantageous coupling of solar radiation into thin film solar cell devices via the use of rare-earth metal oxide (REOx), rare-earth metal oxynitride (REOxNy) and rare-earth metal oxy-phosphide (REOxPy) glasses and or crystalline material. The rare-earth metal is chosen from the group commonly known in the periodic table of elements as the lanthanide series.