Researchers at the National University of Singapore (NUS) have engineered a material with enhanced thermal resilience. This advancement enables advanced solar cells to maintain their operational efficiency, resulting in the creation of robust, high-performance solar panels. The team's findings have been published in Science.
NUS researchers Dr Zhang Boxue (left), Assistant Professor Park Somin (middle), and Assistant Professor Wei Mingyang (right) developed a heat-resistant material to enhance the stability of perovskite/silicon tandem solar cells. Image Credit: National University of Singapore
While silicon-based solar panels are commonly used, their performance is approaching its maximum potential. Scientists are exploring the combination of silicon with perovskite, a material capable of capturing more sunlight and producing more electricity within a given space.
These combined devices, referred to as perovskite-silicon tandem solar cells, have demonstrated high efficiency levels, nearing 35 %, but their durability over extended periods has been a significant challenge.
The NUS research team has identified a method to extend the lifespan of these tandem solar cells, even when exposed to elevated temperatures. The team's investigation revealed that a slender molecular layer, responsible for linking the perovskite and silicon components, is prone to deterioration when subjected to heat. This degradation leads to a decline in performance over time.
Based on these findings, the team developed an enhanced heat-resistant iteration. This version secures the layers more effectively, enabling the cells to sustain nearly their entire performance capacity, even after 1,200 hours of uninterrupted operation at 65 ºC. Sustained stability is paramount for commercial feasibility, given that the majority of silicon solar panels currently available are backed by warranties spanning 20 to 25 years. Achieving comparable reliability has posed a significant challenge for advanced tandem designs.
Perovskite-silicon tandem cells can produce more electricity than traditional panels, but to be commercially viable, they must stay stable in real-world conditions. We focused on strengthening the weakest link – the ultra-thin molecular layer between the two materials.
Park Somin, Assistant Professor, Department of Chemistry, Faculty of Science, National University of Singapore
Only as Strong as the Weakest Link
Prior investigations frequently linked diminished performance to the perovskite material. However, the NUS research team determined that the actual cause lies within the extremely thin contact layer that connects the perovskite material to silicon.
The team of researchers initially replicated high-efficiency tandem solar cells documented in existing research. They then assessed their functionality under constant light and heat conditions.
The findings indicated that the perovskite remained stable. However, the thin "hole-transport" layer, which facilitates the movement of electrical charge between layers, started to degrade. This layer, identified as a self-assembled monolayer (SAM), progressively lost its organized structure upon heating. This impeded the current flow throughout the device.
Conventional SAMs act like a carpet of molecules that helps charges move across. When they get too warm, the fibers start curling up, leaving gaps that block the flow of electricity.
Wei Mingyang, Assistant Professor and Co-Corresponding Author, Department of Materials Science and Engineering, College of Design and Engineering, National University of Singapore
The research group developed an enhanced version of the SAM that could “lock” itself together into an interconnected network. As the molecules self-assemble, they form minute chemical connections with each other, resulting in a firmly connected layer that can withstand elevated temperatures and maintain its structural integrity during operation.
This cross-linked molecular interaction enhanced the connection between the layers, facilitating the solar cell's ability to sustain high efficiency over extended periods.
Making It Work in the Real World
With the incorporation of the novel cross-linked layer, the perovskite-silicon tandem cells fabricated by the NUS researchers achieved efficiencies surpassing 34 %, which includes a certified measurement of 33.6 % from an external testing facility.
Certification holds significance as it validates that the findings have undergone independent assessment under standardized testing parameters. This provides researchers and industry collaborators with assurance that the documented performance can be replicated.
The tandem cells exhibited exceptional stability, retaining more than 96% of their original performance after 1,200 hours of uninterrupted illumination at 65 °C. This level of resilience is relatively uncommon in solar cells utilizing perovskite materials.
Identifying the root cause of the performance degradation – the SAM, and then reinforcing it, is the breakthrough needed to enhance the stability of these solar cells. It is an elegantly simple yet effective way to make these high-efficiency cells more reliable without adding manufacturing complexity.
Park Somin, Assistant Professor, Department of Chemistry, Faculty of Science, National University of Singapore
The findings achieved by the research group represent a significant advancement in the development of deployable perovskite-silicon solar panels, which have the potential to yield a greater energy output from an equivalent surface area, whether installed on rooftops or within solar energy farms.
Asst. Prof. Wei says, “Our work helps bridge the gap between laboratory performance and real-world reliability. Our next goal is to test these prototypes under actual tropical conditions and to scale them up to module sizes suitable for deployment. Testing in Singapore’s hot and humid climate will be particularly helpful, as such conditions accelerate material degradation and provide a rigorous test of durability.”
Journal Reference:
Zhang, B., et al. (2025) A cross-linked molecular contact for stable operation of perovskite/silicon tandem solar cells. Science. DOI:10.1126/science.ady6874. https://www.science.org/doi/10.1126/science.ady6874.