TCO Workfunction in N-Silicon Oxide Emitter – c-Si (P) Heterojunction Solar Cell: An Open Issue

The amorphous/crystalline silicon heterojunction solar cells have largely demonstrated to be high efficiency capable. Despite the highest efficiency cells are based on high quality n-type c-Si absorber, the p-type hold more than 90% of the world silicon solar cell market, so it seems important to improve device and cost efficiency using p-type substrates. An issue of is related to the amorphous layer absorbance so different materials have been studied and tested as replacing emitter to obtain a gain in terms of transmittance, conductivity and Jsc. We have adopted a different and wider bandgap emitter based on silicon oxide, n-SiOx. A central role in this type of structure is played from the chosen TCO workfunction, whose value affects strongly the heterojunction’s band structure at the emitter interface. RF magnetron sputtered TCO obtained with different deposition parameters, have been made in order to optimize their use in our heterojunction solar cell. Numerical simulation on the SiOx HJ, with TCO having proper workfunction value, show potential efficiency conversion well over the 23%