Longi Sets New World Record with 34.85% Efficiency in Tandem Perovskite Solar Cell.

Chinese solar manufacturer Longi has achieved a major breakthrough by reaching a power conversion efficiency of 34.85% .

By
Abdul Rafay
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Chinese solar manufacturer Longi has achieved a major breakthrough by reaching a power conversion efficiency of 34.85% for its two-terminal tandem perovskite solar cell, setting a new world record for this type of device.

The result was certified by the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL), confirming the performance and making it a significant milestone in photovoltaic research.

📈 Breaking Its Own Record

This achievement surpasses Longi’s previous record of 34.6% efficiency, set in September 2024. At that time, the company had published a detailed scientific paper outlining the cell’s design, which was first introduced in November 2023.

🚀 Crossing the Shockley-Queisser Limit

Longi’s new result is the first certified efficiency to go beyond the Shockley-Queisser limit of 33.7% for single-junction solar cells, marking a significant advancement in tandem solar cell technology.

🔬 The Science Behind the Cell

The record-breaking efficiency is attributed to a bilayer interface passivation strategy designed to optimize both electron transport and hole blocking. This involves:

  • A thin layer of lithium fluoride (LiF), which enhances passivation while minimizing resistive losses.
  • The use of ethylenediammonium diiodide (EDAI) molecules, which chemically passivate areas not covered by the LiF layer, forming localized nano-contacts at the perovskite/C60 interface.

Together, these innovations suppress interfacial recombination and improve charge extraction, leading to better overall performance.

🏗️ Advanced Cell Structure

Longi’s team also employed a patented design for silicon heterojunction solar cells using an asymmetric textured surface:

  • The front surface has a fine texture that supports the formation of the perovskite film.
  • The rear surface features a standard large-texture design to enhance passivation and infrared spectral response.

As a result, the cell achieved an open-circuit voltage of 1.97 V and a fill factor of 83.0%, both key indicators of high-performing solar devices.

🤝 Backed by Academic Powerhouses

This breakthrough was made possible through collaboration with:

  • Suzhou University
  • Huaneng Clean Energy Research Institute
  • The Hong Kong Polytechnic University (HKPU)