Novel layer stacks and contacting materials (WP4)
WP4 was focused on the development of functional layers to enable the fabrication of high-efficiency IBC devices. This involves passivating and antireflective coating on the front side, charge-collecting layers on the rear side, and metallization. Ensuring excellent light incoupling and minimizing resistive losses were key objectives in that respect.
Most targets were achieved within the project duration. The optical goals prove to be achievable with simpler strategies than the series-resistance ones. For the latter, we compared approaches from all partners early-on to assess the most promising routes and used dedicated test structures to then improve the best performing layers. Targets in terms of layer-stack properties were reached, enabling to push the efficiency of the solar-cell devices to targeted levels. Alternative routes showing high promises, yet lower performances so far were still explored further to pave the road for tomorrow’s technology.
Outputs from this WP are two-fold: First, they enabled to fulfil the goals of the NextBase project, hence to demonstrate an industry-feasible high-efficiency silicon photovoltaic module using the back-contact technology. Second, scientific knowledge was gathered on several film properties, and in particular in the highly promising field of “dopant-free” solar cells which combine non-silicon material as contacts to silicon wafer absorber in a photovoltaic device.
During this project, I clearly learned that identifying the good metrics to assess the targeted properties are extremely important. Also identifying at the project-writing stage the possible limitations and mitigation strategies is key to avoid being stuck later on with promises which cannot be fulfilled. While being ambitious, staying realistic is very important and keeping alternative routes open is key to a successful outcome.