Key takeaways:
JinkoSolar presented process and material optimization strategies for improving the efficiency and stability of perovskite-TOPCon tandem cells
New interface layers and additive engineering improved hole selectivity, crystallization quality, and perovskite layer uniformity
Stability studies showed tandem cells retaining over 80% performance after 1,000 hours of high-temperature MPP operation
According to PV InfoLink, TOPCon will maintain its workhorse status through 2028, with a market share of over 78%. Given its standing, it becomes natural to explore the evolution pathways for TOPCon. This drives further research into perovskite-silicon tandem technology, in which TOPCon is used as the bottom cell.
At the TaiyangNews Next-Generation PV Technology Conference 2026, Menglei Xu, R&D Director at JinkoSolar, presented progress in perovskite-silicon tandem technology and process developments that resulted in a tandem cell achieving a 34.76% efficiency. This was achieved by using commercial TOPCon cells with over 27% efficiency and a Voc of over 748 mV. High Vocs are a must in order to achieve high efficiency in 2T tandem cells.
For this tandem cell, the layers of the perovskite cell are added on the rear side of the TOPCon cell rather than to the front, basically flipping the TOPCon cell to add the perovskite top cell. But since the rear side has a planar surface, it is texturized to achieve pyramids of about 0.6-0.7 µm.
With this approach, and applying n-polyfingers on the front and full-area p-poly on the rear of the bottom cell, a conversion efficiency of 32.73% was achieved. However, the light absorption by the p-poly region on the rear limited the Jsc of the final tandem cell to only 20.4 mA/cm² due to the parasitic absorption in the p-poly region.
Additionally, optimizations to the perovskite cell included the introduction of a new self-assembled monolayer (SAM) on the NiOx layer around 2 years ago. This improved the hole selectivity and helped achieve a Voc of 2.01 V in the perovskite-silicon tandem cell.
To ensure stability, additives such as thioacetylacetamide hydrochloride (TAACl) were used in perovskite precursor solutions. This resulted in a more uniform distribution of bromine (Br) and less phase separation in the perovskite cell under operation. Additional additives, such as 2-mercaptobenzothiazole, were explored to optimize perovskite crystallization. In a 2T tandem cell, crystallization is faster than in a single-junction perovskite on a glass substrate, resulting in a poor-quality perovskite layer. Using these improvements, the tandem cell achieved an efficiency of 32.76%, with 91% of it retained after 1,700 h of continuous operation.
Another additive is potassium salt to improve the uniformity of the perovskite layer on the textured surface. This development achieved an efficiency of 33.65%, which – under maximum power point (MPP) tracking at a high temperature (85°C) for 1,000 h – maintained above 80% of its performance.
There is further scope to optimize these processes and improve the efficiency and stability of perovskite-silicon tandem cells. Xu concluded that currently, all configurations, such as 2T, 3T, and 4T, are promising, but scaling these technologies into commercial products is key. He ended his talk by projecting that a commercial-scale perovskite tandem with 100s of MW capacity would be online in about 3 years, and a GW-scale line in about 4-5 years. Access his full presentation here.