The change to certain materials or processes is dictated by the better functionality and less cost. It is so, that TiO2 passivization layers can act also as anti reflection coating while Al2O3 can serve as passivization layer only. Both are produced by the the atomic layer deposition technologist. So, titanium dioxide is preferable.
For more information please return to the papers in the links; https://www.ise.fraunhofer.de/de/veroeffentlichungen/konferenzbeitraege/2009/24th-european-photovoltaic-solar-energy-conference-and-exhibition-hamburg-germany/benick_2bp.1.3.pdf
and http://www.hindawi.com/journals/ijp/2013/431614/
The change to certain materials or processes is dictated by the better functionality and less cost. It is so, that TiO2 passivization layers can act also as anti reflection coating while Al2O3 can serve as passivization layer only. Both are produced by the the atomic layer deposition technologist. So, titanium dioxide is preferable.
For more information please return to the papers in the links; https://www.ise.fraunhofer.de/de/veroeffentlichungen/konferenzbeitraege/2009/24th-european-photovoltaic-solar-energy-conference-and-exhibition-hamburg-germany/benick_2bp.1.3.pdf
and http://www.hindawi.com/journals/ijp/2013/431614/