A Game-Changing Advance from NUS in Solar Cell Durability
Researchers at the National University of Singapore (NUS) have made headlines with a pioneering achievement in renewable energy technology. Their latest work, published in the prestigious journal Science, introduces a novel vapour-deposition method that stabilizes perovskite-silicon tandem solar cells on industrial-grade textured silicon wafers. This breakthrough addresses one of the biggest hurdles in bringing these high-efficiency cells to market: long-term stability under real-world conditions.
Perovskite-silicon tandem solar cells combine the strengths of two materials: perovskites, which excel at absorbing higher-energy light, and silicon, the workhorse of current photovoltaics. By stacking them, efficiencies can surpass 30%, far beyond single-junction silicon cells topping out around 27%. Yet, perovskites' notorious instability to heat, moisture, and light has kept them confined to labs. The NUS team's innovation changes that, proving these tandems can endure over 2,000 hours of operation, including extreme tests at 85°C.
Led by Assistant Professor Hou Yi from NUS's Department of Chemical and Biomolecular Engineering and head of the Perovskite-based Multijunction Solar Cells Group at the Solar Energy Research Institute of Singapore (SERIS), this research positions Singapore's higher education institutions at the forefront of clean energy innovation. For academics, students, and professionals eyeing research careers, this underscores the vibrant opportunities in Singapore's university sector. Explore research jobs or university jobs to join such cutting-edge teams.
Decoding Perovskite-Silicon Tandem Solar Cells
To grasp the significance, let's break down the basics. Traditional silicon solar cells, or photovoltaic (PV) cells, convert sunlight into electricity via the photovoltaic effect, where photons excite electrons across a bandgap. Silicon's bandgap of about 1.1 electron volts (eV) captures much of the solar spectrum but misses higher-energy blue and UV light, leading to losses.
Perovskites—named for their crystal structure resembling the mineral perovskite (calcium titanium oxide)—are hybrid organic-inorganic materials like methylammonium lead iodide (MAPbI3). Their tunable bandgap (1.5-2.3 eV) absorbs the spectrum silicon ignores. In a tandem configuration, a wide-bandgap perovskite top cell filters high-energy photons, passing the rest to a narrow-bandgap silicon bottom cell, theoretically reaching 45% efficiency under the Shockley-Queisser limit for tandems.
Singapore's tropical climate, with high humidity and temperatures, demands robust PV tech. NUS's SERIS, established in 2008, has been pivotal, pioneering floating solar and building-integrated photovoltaics (BIPV). This tandem work builds on SERIS's track record, including a 26.4% efficient perovskite-organic tandem in June 2025.
For those pursuing higher education in materials science or engineering, NUS offers programs blending theory and industry application. Check Singapore academic opportunities or tips for academic CVs.
The Critical Hurdle: Stability on Industrial Wafers
Lab perovskites hit 34% tandem efficiency, but commercialization falters on stability. Solution-processed perovskites (spin-coating inks) work on flat lab substrates but fail on micrometre-scale pyramid-textured silicon wafers used in industry for light trapping. These textures boost silicon efficiency by 5-10% but create adsorption imbalances during vapour deposition: inorganic precursors stick better than organics, yielding defective films that degrade fast under heat.
Vapour deposition—evaporating precursors in vacuum—is scalable like silicon fabs but hadn't succeeded on textured wafers. Previous attempts led to phase impurities and rapid failure. NUS's solution? A surface modifier revolutionizing this process.
Innovative Vapour-Deposition Technique Explained Step-by-Step
The NUS method uses co-evaporation: lead iodide (PbI2), cesium bromide (CsBr), and formamidinium iodide (FAI) vapours deposit simultaneously. The game-changer is pretreating the silicon with 3,3,3-trifluoropropyl-trimethoxysilane (TFPTMS). This silane self-assembles, its fluorine atoms forming hydrogen bonds with organic cations (FA+), boosting organic adsorption energy by 0.5 eV per density functional theory (DFT) calculations.
Step 1: Functionalize textured silicon bottom cell with TFPTMS via vapour priming.
Step 2: Co-evaporate precursors, achieving balanced partitioning for uniform, cubic-phase perovskite films.
Step 3: Cap with electron transport layer and top contacts.
X-ray diffraction and nanobeam electron diffraction confirm phase purity across pyramids. Without TFPTMS, films are PbI2-rich and unstable.
Photo by Janick Toma on Unsplash
Impressive Performance Metrics and Benchmarks
The resulting 1 cm² tandems achieve 31.3% power conversion efficiency (PCE), certified under standard conditions (AM1.5G, 1000 W/m², 25°C). Stability shines: T90 (90% initial PCE retention) exceeds 1400 hours at 85°C 1-sun—demanding for warranties (25-year industry standard projects ~30,000 hours). Room-temperature operation lasts >2000 hours with minimal degradation.
- Compared to prior vapour tandems: 2x longer T90 on textured Si.
- Vs solution-processed: Scalable, uniform on industrially textured wafers.
- Outperforms single-junction Si (26-27% commercial).
These metrics validate IEC standards for modules. Read the full paper in Science.
For researchers, such data highlights rigorous testing's role. Aspiring postdocs? View postdoc positions.
The Team Driving Innovation at NUS SERIS
Asst Prof Hou Yi, a Presidential Young Professor, leads with expertise in scalable PV. Collaborators span SERIS, NUS College of Design and Engineering, A*STAR, and Trina Solar. Hou notes: "This addresses compatibility with industrial wafers and heat stability simultaneously." SERIS's legacy includes world-record tandems, cementing NUS as Asia's solar hub.
Singapore universities foster such interdisciplinary work. Link to global higher ed trends or SG jobs.
Implications for Singapore's Higher Education and Energy Goals
Singapore, import-dependent for energy, targets 2 GWp solar by 2030 via innovative deployments like floating PV on reservoirs. NUS SERIS advances this, creating research ecosystems. This boosts STEM jobs in universities: from PhDs fabricating cells to faculty leading grants.
Stakeholders praise: Industry eyes scalable tandems cutting levelized cost of energy (LCOE) below $0.03/kWh. Policymakers align with Green Plan 2030. For students, NUS programs in chemical engineering offer hands-on PV research.
Discover research assistant jobs or postdoc advice. Details in NUS release.
Global Ripple Effects and Commercial Pathways
Worldwide, tandems could double PV growth, hitting net-zero faster. Challenges remain: scaling to 6-inch modules, encapsulation. NUS plans pilot lines with partners. Economic impact: Perovskites' low material costs ($10-20/m² vs silicon's $100+) democratize solar.
- Benefits: Higher efficiency = less land; stability = longer life.
- Risks: Supply chain for precursors; recycling.
Ties to faculty roles in sustainable tech.
Future Outlook: From Lab to Rooftops
Hou's team targets full modules under IEC tests. Singapore's fab expertise accelerates. By 2030, expect commercial tandems. For careers, solar research booms—higher ed jobs abound.
Career Opportunities in Solar Research at Singapore Universities
This breakthrough signals demand for experts. NUS hires postdocs, lecturers in PV. Skills: Materials synthesis, device physics, scalability. Advice: Publish in high-impact journals, collaborate industry. Visit rate my professor, career advice, jobs.
