Intense pulsed light handling for 23.0%- efficient silicon heterojunction solar cells

• Scientists at Germany's Fraunhofer Institute for Solar Energy Systems (ISE) have made use of extreme pulsed light (IPL) processing for the growth of a busbarless silicon heterojunction solar cell. The gadget was manufactured with poly-Si-based tunnel oxide passivating calls, which were applied on both sides of the wafer.

Scientists at Germany's Fraunhofer ISE have actually established a silicon heterojunction (SHJ) solar cell making use of intense pulsed light-processed screen-printed metal calls, and also insurance claim to have actually attained a conversion efficiency of 23.0% with this approach.

Rather than commonly used thermal annealing, the researchers utilized extreme pulsed light (IPL) handling, which is a less expensive roll-to-roll strategy for fast thermal processing of numerous thin films. It is generally utilized for sintering silver-, copper-, or nickel-based electrodes of printed electronic devices and, in PV research, for sintering copper-based electrodes on silicon wafers and also on metal-compound-based heterojunction structures.

The team explained that IPL mostly includes noticeable light, delivered in millisecond-lasting pulsed electromagnetic radiation for rapid heating of the cell's low-temperature steel calls. "On standard, IPL-annealed SHJ cells surpass their thermally treated pendants by 0.3-- 0.4%abdominals, specifically as a result of greater open-circuit voltages and also fill elements," the group defined, including that thermal annealing needs the use of bigger as well as a lot more cost-intensive manufacturing devices.

IPL, nonetheless, is restricted by the temperature level restraints of the sensitive amorphous silicon heterojunction framework. An even more useful application for the innovation, according to the scientists, are more temperature-tolerant poly-Si-based tunnel oxide passivating calls, which they used on both sides of the wafer.

The get in touches with were coated with indium tin oxide (ITO) with DC magnetron sputtering, which is a vacuum covering technique frequently made use of for the deposition of several sorts of product in cell manufacturing as well as elsewhere. The radiative power of the IPL handling, according to Fraunhofer ISE, is not only absorbed by the wafer, however also by the metallization itself. "This quantity of energy absorbed by the metal contacts causes a considerable finger resistance reduction," it stated, noting that this decrease likewise results in a rise of the contacts' lateral conductivity. Moreover, get in touch with resistivities at the metal electrode/ITO contact well below 10 mW · cm ² were accomplished.

"Full-size IPL-processed busbarless SHJ cells are produced showing an individually licensed efficiency of approximately 23.0%," the scientists attested, including that conversion effectiveness of the cell was accredited by Fraunhofer ISE CalLab.

Moreover, the IPL technique was additionally related to screen-printed 2 cm x 2 cm-sized solar cells with TOPCon contacts on both sides and also open-circuit voltage values of as much as 709.3 mV were achieved.

"According to the International Technology Roadmap for Photovoltaic, silicon heterojunction technology is already turning into mass production," study co-author, Jörg Schube, informed pv magazine. "In fact, it is expected to acquire a market share of more than 10% within the next five years." He additionally discussed that maximized commercial annealing procedures utilizing IPL can better lead the way for success.

The IPL processing was described in the paper Intense pulsed light in backside processing of solar cells with passivating get in touches with based on amorphous or polycrystalline silicon layers, published in Solar Energy Materials and Solar Cells.