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Modular systems to produce tandem perovskite-silicon cells on 6-inch wafers

Scientists at German research center Helmholtz-Zentrum Berlin (HZB) are planning to bring the perovskite-silicon tandem solar technology to mass production over the coming few years. Our goal is to increase the efficiency of these novel cells to more than 30 percent – not only at laboratory scale, but also when produced on a commercial scale,”  said Bernd Stannowski, which is the head of the Competence Centre Photovoltaics Berlin (PVcomB) at the HZB.

Stannowski and his group are currently working on the development of new modular manufacturing systems to make the large-scale production of solar cells on six-inch wafers possible.

They explained that for the lower part of the tandem cell, which is that made with a silicon heterojunction, very thin amorphous-silicon contact layers produced by plasma-enhanced chemical vapour deposition (PECVD) are needed, and that they are now testing a solution offered by Swiss company Indeotec, which specializes in the development and construction of PECVD/PVD deposition systems for pilot production and R&D purposes. “As the first system of its kind in the world, it has what is known as PECVD-Mirror process modules with which silicon wafers can be coated on both sides – without having to flip them”, Stannowski stated.

As for the tandem cell’s upper layer, which is the active perovskite material, the HZB’s Integration & Novel Technologies laboratory (HySPRINT) is designing a special vacuum deposition system for various materials to conduct research into hybrid silicon-perovskite structures with the support of German companies Von Ardenne and Creaphys.

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Furthermore, Stannowksi said that a newly ordered facility, of which no further detail was disclosed, is expected to integrate all necessary process steps for fabricating the perovskite top cell. “Using this unique technology, the complete cell consisting of several layers including the electrical contacts will be able to be produced automatically and at high throughput,” he stated.

Scientists of the HZB achieved an efficiency of 24.16% with a tandem cell combining CIGS and perovskite technology in April. This new record meant tandem cell efficiency surpassed the 23.35% record for a standalone 1cm² CIGS cell set in January 2019 by Solar Frontier. HZB also holds the efficiency record for a perovskite-on-silicon tandem cell, at 29.15%.

According to recent research from France, PV modules made with tandem solar cells will have to show efficiencies of 30% and offer the same lifetime and degradation rate as standard crystalline panels if manufacturers want to hit commercial production. According to the paper – which assesses the potential competitiveness of tandem modules against crystalline silicon products – commercial versions of the latter will reach efficiencies of 22-24% by the end of the decade, and possibly 25% if interdigitated back-contact (IBC) heterojunction products reach commercial production.

Source: pv magazine