Belgian research lab IMEC has revealed solar cells with 18.4% conversion efficiency, at the European Photovoltaic Solar Energy Conference in Hamburg.
The cell is based on the lab's i-PERC (industrial-passivated emitter and rear cells) structure and has a shallow emitter and front metallization using copper plating.
"The shallow emitter results in an enhanced blue response, and thus in a higher conversion efficiency than with a standard emitter," said IMEC.
For the front contacts, a novel metallisation stack is added which is applied to local openings in the antireflective coating.
"Using copper instead of silver adds to the sustainability of solar cell production. IMEC was able to do this because it has extensive experience with copper plating on silicon," said team manager Dr Joachim John.
"A similar efficiency result was obtained with screen printed contacts, but the long-term sustainability and low-cost potential of Cu-based contacting solutions and the fact that this was a first result obtained without dedicated fine-tuning makes this result particularly encouraging."
The results were obtained on 125cm2 cells and are a step on the lab's roadmap to crystalline Si solar cells 40µm thick with efficiencies above 20%.
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