Employing an i-PERC-type solar cell at imec, researchers have been able to demonstrate a best cell efficiency of 20.1% using atomic layer deposition (ALD) Al2O3 passivation with standard screen printed contacts. However, using front-side copper contacts boosted efficiency to 20.6%.
The nanoelectronics research centre used RENA’s InPilot tool for rear-side polishing and emitter removal, and SoLayTec’s spatial ALD tool for Al2O3 deposition at its silicon solar cell pre-pilot line.
“Routinely achieving average conversion efficiencies around 20%, imec’s industrial PERC pre-pilot line enables the development and validation of novel solar cell processes and concepts, and serves as an excellent platform for system suppliers to benchmark their new tools,” noted Dr. Joachim John, Photovoltaic R&D projects responsible at imec. “This supports the acceleration of process implementation in next generation high-throughput solar cell manufacturing.”
The work also reinforced RENA and SoLayTec’s technology and process developments that eliminate a post deposition anneal (PDA) process step, previously needed after Al2O3 deposition, reducing processing costs.
In collaboration with the Institute for Solar Energy Research in Hamelin (ISFH), the equipment partners had said that with the mass production ‘InPassion’ ALD from SoLayTec, costs for Al2O3 layers below 2 euro cents per wafer were achievable.
Franck Delahaye, Product manager solar at RENA added that, “Collaborating at imec with partners across the value chain enables us to benchmark our tools on the highest performance levels. This way, we can verify the impact of our single tools on the overall cell performance and make sure to offer solutions with a strong positive leverage on the costs per watt. Further, this deepens our understanding of the respective interaction between the process steps and strengthens our ability to support and lead overall process integration at our customer’s facilities.”
RENA and SoLayTec will be presenting the results during EU PVSEC in Paris next week. The i-PERC-type silicon solar cells used 160µm thin standard sized (156x156mm2) monocrystalline wafers and generated open circuit voltages up to 655 mV with the 20.1% efficiencies.