LONGi and Sun Yat-sen researchers develop HJT back contact cells with power conversion efficiency of 27.09%

Facebook
Twitter
LinkedIn
Reddit
Email
The research involved testing a number of new manufacturing processes and using a nanocrystalline layer. Image: LONGi.

Researchers from Chinese module manufacturer LONGi and the School of Materials at Sun Yat-sen University have developed heterojunction (HJT) back contact solar cells with a power conversion efficiency of 27.09%.

The results of the tests, published in Nature, note that the majority of recombination losses stem from “the hole-selective contact region” and “polarity boundaries”, and propose new manufacturing processes to minimise these losses.

This article requires Premium SubscriptionBasic (FREE) Subscription

Unlock unlimited access for 12 whole months of distinctive global analysis

Photovoltaics International is now included.

  • Regular insight and analysis of the industry’s biggest developments
  • In-depth interviews with the industry’s leading figures
  • Unlimited digital access to the PV Tech Power journal catalogue
  • Unlimited digital access to the Photovoltaics International journal catalogue
  • Access to more than 1,000 technical papers
  • Discounts on Solar Media’s portfolio of events, in-person and virtual

Or continue reading this article for free

The researchers tested a ten-step cell production process, where steps included wet chemical cleaning, chemical vapour deposition on the rear side of the cells and the use of laser patterning, at LONGi’s commercial HJT back contact (HBC) production line used to produce the company’s M6-sized modules.

The study also involved the replacement of “amorphous silicon layers” in the cells with “nanocrystalline-doped films” to function as transporting layers, which the researchers found improved the power conversion efficiency of the cell. In the study’s abstract, its authors note that using nanocrystalline structures in the transporting layers could help push power conversion efficiency as high as 27.7%.

“Compared to nanocrystalline silicon, amorphous silicon has not effectively suppressed charge carrier transport loss due to inefficient transport at the interface between the doped layer and the transparent conductive oxide layer, not fulfilling band-to-band tunneling mechanism based on direct energy transitions,” wrote the report’s authors in the study. “To enhance efficiency, adopting nanocrystalline silicon technology for improving contact properties is recommended.”

The results were verified by the Institute for Solar Energy Research in Hamelin, Germany, and the testing of these processes at a commercial-scale facility could help accelerate the scaling up of these methods.

The news follows LONGi’s launch of a back contact module, with a power conversion efficiency of 22.3%, earlier this year. Both this module—and the company’s Hi-MO X10 module, which was launched last week—use LONGi’s hybrid passivated back contact (HBPC) cells, as the company looks to continue its research into back contact technology.

11 March 2025
Frankfurt, Germany
The conference will gather the key stakeholders from PV manufacturing, equipment/materials, policy-making and strategy, capital equipment investment and all interested downstream channels and third-party entities. The goal is simple: to map out PV manufacturing out to 2030 and beyond.

Read Next

October 31, 2024
Tongwei has set a record for heterojunction (HJT) power output, with its latest module delivering a maximum power output of 776.2W.
October 31, 2024
Chinese solar manufacturer Huasun has secured a bid to supply 1GW of heterojunction (HJT) modules to a floating solar PV (FPV) project in China.
Sponsored
October 29, 2024
At the UK launch of LONGi’s Hi-MO 9 module, PV Tech spoke with the company’s Europe president, Leon Zhang, about his belief that back contact technology represents the future of crystalline silicon PV.
October 28, 2024
Trina Solar and FuturaSun were awarded funding in the latest Innovation Fund for a 1.5GW HJT and 1.4GW xBC module assembly plant, respectively.
October 24, 2024
Chinese module manufacturer Trina Solar has achieved a 25.9% cell efficiency for a bifacial i-TOPCON solar cell.
October 17, 2024
Carbon has emerged as a third actor in the ongoing patent dispute between rival Chinese manufacturers JA Solar and Astronergy.

Subscribe to Newsletter

Upcoming Events

Solar Media Events
November 12, 2024
San Diego, USA
Solar Media Events, Upcoming Webinars
November 13, 2024
4pm GMT / 8am PST
Solar Media Events
November 19, 2024
Philadelphia, USA
Solar Media Events
November 20, 2024
Zhuhai, China
Solar Media Events
November 21, 2024
London, UK