Perovskite Solar Cells Hit Two Milestones in April: A Certified Efficiency Record and a Stability Breakthrough
A Nature Energy paper from Nanchang University achieves 26.61% certified efficiency with cesium doping, while a private Chinese cell surpasses all single-junction silicon cells at 27.98%.
Overview
April 2026 produced two significant advances in perovskite solar technology within the span of a few weeks. Researchers at Nanchang University in China published a peer-reviewed technique in Nature Energy that achieved a certified efficiency of 26.61% while also demonstrating exceptional thermal durability. Days earlier, a separately reported Chinese cell reached 27.98% efficiency — surpassing all single-junction silicon solar cells ever tested in a laboratory setting for the first time. Together, the results accelerate a years-long push to make perovskite-based solar commercially viable alongside, and potentially in place of, conventional silicon panels.
What We Know
The Nanchang University Cesium-Doping Breakthrough
On April 18, a team led by Jiacheng He and Zhao Guo at Nanchang University published research in Nature Energy describing a new approach to doping perovskite films with cesium ions, according to TechXplore. The key innovation is a specially designed chemical compound — cesium 4-(diphenylphosphino)benzoate — that ensures positively charged cesium ions are distributed uniformly throughout the perovskite film rather than clustering unevenly as they typically do.
Uniform cesium distribution stabilizes the material’s crystal structure, specifically the alpha-phase that is most efficient at converting sunlight into electricity. Without this stabilization, perovskite cells tend to degrade as heat causes the crystal to transition out of that optimal phase. The researchers incorporated the compound using a two-step fabrication process that provides greater control over crystal formation, as reported by TechXplore.
The resulting cells achieved an uncertified efficiency of 26.91% and a certified efficiency of 26.61% — a meaningful result given that independent certification is required for any claim to count as a recognized world record. The more significant result, however, may be on durability: devices incorporating a thermally stable charge-transport layer retained 95% of their initial efficiency after 1,500 continuous hours of operation under full sun at 85°C, according to the TechXplore report. That test protocol — called ISOS-L-2 — is the industry standard for simulating long-term outdoor degradation and is among the most demanding benchmarks perovskite cells face before commercialization.
The 27.98% Efficiency Claim
Earlier in the month, on April 3, CGTN reported that a privately developed Chinese perovskite solar cell had reached 27.98% efficiency under standard sunlight conditions, according to the outlet. The report described this as “the first time this technology has outperformed all single-junction silicon solar cell[s] in laboratory testing,” a milestone that solar researchers have been anticipating for several years as perovskite lab records have climbed steadily. The CGTN report did not name the specific institution or company responsible for the result.
The Stability Front: Metal Oxide Layers
In parallel, Halocell Energy and materials supplier Sofab Inks announced on April 8 that integrating metal oxide nanoparticle inks into the charge transport layer of perovskite modules maintained nearly 100% normalized efficiency after 1,300 hours under accelerated testing conditions — 1,000 lux illumination, 85% relative humidity, and 65°C — compared with conventional materials that show roughly 20% efficiency loss after 1,000 hours under similar conditions, according to SolarQuarter. The company said the approach is designed for compatibility with roll-to-roll manufacturing, which could enable scalable production of thin, lightweight, flexible modules for applications including IoT sensors, drones, and space hardware.
Context: Why Stability Has Defined the Race
Perovskite solar cells have held the promise of lower manufacturing costs and higher theoretical efficiency limits than silicon for over a decade. Single-junction silicon cells are bounded by the Shockley-Queisser limit of about 32%, while perovskite’s theoretical ceiling for a single-junction cell is around 31%, as noted by industry analysts tracking the field. But perovskite materials have historically struggled to maintain their efficiency under real-world exposure to heat, humidity, and light, a gap that has kept commercial deployment limited despite rapid laboratory progress.
Mass production is broadly expected to begin in the 2027–2029 timeframe, with market projections ranging from roughly $1.7 billion to $7 billion by 2030 depending on how quickly the technology scales, according to industry forecasts. Tandem configurations that layer perovskite on top of silicon have already reached commercial deployment in limited batches, with Oxford PV shipping 24.5%-efficient tandem panels to U.S. utility customers in late 2024.
What We Don’t Know
The CGTN-reported 27.98% efficiency claim lacks independent verification details. The article did not name the institution or company behind the result, and no peer-reviewed publication has been linked to the claim as of this writing. Whether the result has undergone or will undergo independent certification by a body such as NREL or Fraunhofer remains unclear.
The Nanchang University cesium-doping strategy, while peer-reviewed and certified, has so far been demonstrated at small laboratory scales, with a device area of less than one square centimeter. Whether the approach can maintain its efficiency and stability advantages as it scales to module or panel size is an open question that will likely determine its practical relevance. The efficiency-area trade-off is a persistent challenge: lab cells routinely reach well above 25%, while commercial-scale modules currently achieve in the range of 24.5–28.6% efficiency, according to analysts tracking the sector.
The long-term toxicity and disposal implications of lead-based perovskite materials also remain an active area of regulatory and scientific scrutiny, particularly in the European Union, where new battery and solar panel regulations are tightening environmental requirements for end-of-life handling.