Longi, a leading Chinese solar manufacturer, has set multiple efficiency records for tandem perovskite-silicon solar cells, with the latest achieving a record efficiency of 34.58%, published in a Nature paper.

In September 2024, Longi demonstrated a tandem cell efficiency of 33.9%, surpassing previous benchmarks, and currently holds the world record at 34.85%, slightly higher than the recent record.

Their advancements include efficiencies of 34.6% and 33.9% in earlier reports, showcasing continuous progress in this technology.

The recent record-breaking device, measuring 1 cm², achieved a power conversion efficiency of 34.58%, with an open-circuit voltage of 2.001 V and a fill factor of 83.79%.

This breakthrough was made possible through innovative interface engineering, including the use of asymmetric self-assembled monolayers (SAMs) like HTL201, which improve passivation, coverage, and energy level alignment.

The team employed a bilayer passivation strategy with nanoscale lithium fluoride and diammonium diiodide molecules to reduce non-radiative recombination, boosting efficiency.

Collaborating with Soochow University, Longi designed an asymmetric carbazole-based SAM for better interface coverage and energy alignment, further enhancing device performance.

The top perovskite layer includes a silver contact, lithium fluoride layer, EDAI molecules, and a C60 electron transport layer, while the textured silicon bottom cell contributes to high efficiency.

These technological advances are part of Longi’s broader mission to promote sustainable energy development, including innovations in hydrogen solutions.

Longi’s research, including collaborations with the Chinese Academy of Sciences, has led to core innovations such as bilayer passivation and stable conjugated SAMs, significantly improving efficiency and stability.

Their efforts are contributing to China’s development of a high-performance, industry-academic integrated tandem solar cell ecosystem, pushing the boundaries of photovoltaic efficiency beyond traditional limits.