Researchers from King Abdullah University of Science and Technology (KAUST) and Helmholtz-Zentrum Berlin (HZB) have developed a perovskite-silicon tandem solar cell that achieves efficient charge extraction and interface passivation. The team improved the performance of blade-coated tandems by introducing 2D perovskite layers at the bottom interface.
Image credit: Joule
These modifications enhanced the blade-coated tandem performance to a certified PCE of 31.2%, owing to efficient charge extraction and interface passivation. This work demonstrates the efficiency potential for scalable ink-based fabrication, emphasizing stability and manufacturability, which are crucial for the widespread adoption and commercial success of this promising photovoltaic (PV) technology.
The team explained that they used blade coating instead of spin coating, as the latter currently faces scalability issues due to limited throughput. It was used, in particular, to deposit the 3D perovskite onto a 2D perovskite layer in the perovskite top device, which had a p-i-n inverted device configuration. By tuning the targeted dimensionality (n) of the 2D perovskite film, which is made prior to the 3D perovskite, the researchers minimized the energy level mismatch at the bottom interface, achieved efficient hole extraction, and reduced performance losses in their blade-coated p-i-n devices. This configuration helped the top perovskite device achieve a power conversion efficiency of 22.6%, an open-circuit voltage of 1.23V, and a fill factor (FF) of 82%.
With this device, the research group built a 1 cm2 encapsulated tandem device based on a substrate made of indium tin oxide (ITO), several layers of amorphous silicon (a-Si), a crystalline silicon absorber, a transparent back contact made of indium zinc oxide (IZO), the 2D perovskite layer, the blade-coated 3D perovskite layer, a p-phenylenediaminium iodide (PDAI) layer, an electron transport layer (ETL) made of thermally evaporated buckminsterfullerene (C60), a tin oxide (SnO2) layer, another IZO layer, an anti-reflective coating based on magnesium fluoride (MgF2), and a silver (Ag) metal contact.
Tested under standard illumination conditions, this tandem cell also showed it can retain around 80% of its initial efficiency for 1,700 h under 1-sun. “Our overall strategy, with robust perovskite composition and bottom 2D interface, enabled blade-coated tandems to be certified for the first time in literature, with an efficiency of 31.2% measured at Fraunhofer Institute for Solar Energy (ISE) Systems,” the scientists stated.
