HKUST(GZ) Team Publishes Findings on Perovskite Solar Cells in Science
As the vision of "ubiquitous power generation" approaches reality, perovskite solar cells have emerged as one of the most promising candidates among renewable energy technologies.
Perovskite solar cells, as third-generation devices, possess a high theoretical efficiency, low‑cost fabrication, and significant application prospects. Nonetheless, their commercialization has been hindered for a long time primarily due to stability issues.
While much of the scientific community has focused on the long-term degradation of perovskite solar cells, researchers at the Hong Kong University of Science and Technology (Guangzhou) have uncovered a critical oversight — these devices may be compromised from the moment they are fabricated.
On Aug 20, the team published a paper in the journal Science, titled "Redirecting wet-interfacial redox pathways for efficient inverted perovskite solar cells", revealing a previously overlooked chemical issue occurring during fabrication: harmful reactions between interface materials and perovskite precursors can introduce invisible defects that undermine both efficiency and operational lifespan.
Led by Assistant Professor Yong ZHANG of the Function Hub, Sustainable Energy and Environment Thrust, the study features first author Zheng LIANG, a research assistant in Professor ZHANG's group. Additional HKUST(GZ) co-authors include research assistant Shengbin CHENG, doctoral student Yuqi BAO, and Assistant Professor Yuheng LI. The work was conducted in collaboration with research partners from Sungkyunkwan University, Contemporary Amperex Technology (CATL), Nankai University, and Shanghai Jiao Tong University.
Link to the research article:
https://www.science.org/doi/10.1126/science.aeg8415
The discovery traces back to July 2025, when Zheng LIANG, the paper's first author, noticed a subtle color change in a perovskite precursor solution during a routine experiment. This seemingly minor observation prompted an in-depth investigation using liquid chromatography and nuclear magnetic resonance spectroscopy.
The team found that the phosphonic acid groups on the self-assembled molecules (SAM) film, a key component of the cell, possess weak acidity, which activates the DMSO solvent. This triggers a cascade of undesirable redox reactions, generating iodine-related impurities that damage the perovskite crystal structure.
What further frustrated the researchers was the scaling effect: as solar cells grow larger, the drying and solidification time of the liquid precursors lengthens, allowing these harmful reactions to occur more extensively. This mechanistic insight explains why transitioning perovskite cells from small laboratory samples to square-meter-scale panels has proven so challenging, a long-standing bottleneck in the industry's quest for industrialization.
The Science reviewers commended the study, noting that it not only elucidates the SAM-perovskite interaction mechanisms during solution processing, but also fills a critical gap in understanding interface formation, thereby charting a new course for performance optimization.
"Identifying the problem is truly the beginning of everything, and it is more important than solving it," said Professor ZHANG. "What we need to do is to first understand the real issues at hand."
In response, the team developed a targeted countermeasure using hydrazide-based additives. These compounds neutralize acidity, prevent the formation of harmful impurities, and enhance the cell's conductive properties. This dual-action strategy not only rectifies initial defects but also boosts overall device efficiency.
The results have been remarkable. Small-area perovskite cells achieved a record power conversion efficiency of 27.7 percent, independently verified by third-party certification. Furthermore, in collaboration with Contemporary Amperex Technology (CATL), the team scaled up the technology, attaining a 20.1 percent efficiency on 2 m2 large-scale modules, marking a significant step toward commercial viability.
The enhanced cells also demonstrated outstanding durability, retaining over 95 percent of their initial performance after 2000 hours at 85 °C and maintaining stable operation for 1500 hours under high-humidity conditions. These metrics not only exceed the photovoltaic industry's entry-level requirements, but also signal that perovskite technology is rapidly narrowing the performance gap with conventional silicon-based solar cells.
Beyond advancing perovskite applications, this research introduces a new paradigm in solar cell design: the critical importance of chemical compatibility between interface materials and active layers.
"To become a scientist, one must first become an artist," Professor ZHANG often told LIANG. Perhaps what artists see is not an unseen world, but rather the details that others overlook, such as a test solution that has subtly changed color.
"The insights gained from this observation not only led to more efficient and stable perovskite solar cells but also established a new design principle," ZHANG added. "When designing interface materials, we must consider not just their electrical properties, but also their chemical compatibility with the other materials. This principle applies broadly: whenever different chemical substances come into contact, interfacial reactions can occur and affect device stability."
Looking ahead, the team plans to explore recycling strategies and sustainable production methods for perovskite solar cells, aiming to further reduce their environmental footprint.
In the realm of scientific discovery, the most profound breakthroughs often arise from noticing what others dismiss. For Professor ZHANG and his team, a simple color change in a solution became the key to unlocking new frontiers in solar energy.
