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.

Not ready to commit yet?
  • 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.

Read Next

August 28, 2025
Bahraini, Chinese, Egyptian and Emirati groups have agreed to develop a new solar and storage manufacturing facility in Egypt
Premium
August 27, 2025
American Clean Power Association’s MJ Shiao assesses the state of US PV manufacturing in the wake of recent policy developments.
August 26, 2025
China has added 11.04GW of solar PV capacity in July 2025, a 48% decrease from the same period a year ago, according to data from China's National Energy Administration.
Premium
August 22, 2025
Radovan Kopecek and Joris Libal examine the technological and economic factors driving PV’s ascendancy, with emphasis on bifacial BC modules.
August 21, 2025
JA Solar's CTO, Zi Ouyang, discusses the company's latest module technologies and why the future is tandem.
August 18, 2025
Chinese module manufacturer LONGI has launched a new back-contact (BC) lightweight module for commercial and industrial (C&I) rooftop applications.

Subscribe to Newsletter

Upcoming Events

Solar Media Events
September 16, 2025
Athens, Greece
Solar Media Events
September 30, 2025
Seattle, USA
Solar Media Events
October 1, 2025
London, UK
Solar Media Events
October 2, 2025
London,UK
Solar Media Events
October 7, 2025
Manila, Philippines