Researchers at Soochow University has developed a perovskite/silicon tandem solar cell that reached a laboratory power conversion efficiency of 34.0 %. An independently certified device achieved a steady-state efficiency of 33.5 % and an open-circuit voltage of 2.014 V. This voltage is among the highest reported value for this class of solar cells. The study has been published in Science Bulletin .
Perovskite/silicon tandem solar cells combine a wide-bandgap perovskite top cell with a silicon bottom cell to use sunlight more efficiently than conventional single-junction silicon cells. Their performance, however, is limited by uneven perovskite growth on textured silicon and non-radiative recombination at the interface with the hole-transport layer. Many earlier passivation strategies reduced recombination but also slowed charge extraction, creating a difficult trade-off between voltage and charge transport.
The study was led by Prof.Jiang Liu, Prof.Xiaohong Zhang and Dr.Hongbo Mo at Soochow University, together with Dr.Bo He at LONGi Central R&D Institute. Huimin Zhang and Qingshui Zheng contributed equally as first authors. The team inserted discrete monoclinic zirconia nanoparticles, known as ZrO 2 , between the transparent conductive oxide and a self-assembled monolayer. This modification created a nanoscale interfacial scaffold without forming a continuous insulating layer.
At the buried interface, the zirconia nanoparticles do two things at once. First, they change the surface energy, helping the perovskite precursor solution spread more evenly. That leads to denser, void-free films with larger grains. Second, the discrete nanoparticles form nanoscale localized contacts at the interface. The zirconia regions provide field-effect passivation that suppresses non-radiative recombination, while the exposed monolayer pathways preserve efficient hole extraction. The high dielectric constant of zirconia also helps screen local electrical fluctuations, limit charge accumulation and reduce device hysteresis. X-ray photoelectron spectroscopy supported the formation of Zr–O–P bonds between zirconia and the monolayer molecules. Together with the bonding between the monolayer and conductive oxide, these links create a dual-anchoring network that improves molecular attachment and coverage uniformity.
Microscopy and spectroscopy supported the proposed mechanism across the modified interface. Conductive atomic force microscopy and Kelvin probe measurements showed more uniform current and surface potential distributions. Time-resolved photoluminescence measurements showed that the average carrier lifetime increased from 1.46 to 2.81 μs after the combined modification. Ultraviolet photoelectron spectroscopy indicated improved energy alignment for hole extraction, while impedance measurements showed reduced interfacial recombination.
The champion tandem cell reached an efficiency of 34.0 % and an open-circuit voltage of 1.997 V. Its short-circuit current density was 20.36 mA cm -2 , with a fill factor of 83.62 %. Independent certification confirmed an open-circuit voltage of 2.014 V and a steady-state efficiency of 33.5 %.
Durability tests tell a similar story. Encapsulated devices were run under continuous one-sun illumination at maximum power point and room temperature. After 2000 h, the zirconia-modified device still delivered 84% of its initial efficiency.
The results show that a carefully patterned insulating interface can improve perovskite film growth and suppress recombination without blocking charge extraction. This nanoscale interface design provides a practical strategy for developing more efficient and durable perovskite/silicon tandem solar cells.
Science Bulletin
Experimental study