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Since 2017, the efficiency record for cast multi-crystalline silicon (mc-Si) solar cells has been 22.3% using a TOPCon design on a 2 × 2 cm2 area of an n -type wafer processed in the laboratory. As the efficiency of industrial PERC and TOPCon cells on monocrystalline wafers has been higher than that, there is widespread expectation that multi-crystalline materials will be used less and less. Recently, we applied our industrial TOPCon (i-TOPCon) technology to 157.4 mm × 157.4 mm quasi-mono n -type wafers and achieved an efficiency of 23.22% with V oc of 711.9 mV with illumination for the front side, independently confirmed by ISFH CalTeC in Germany. To the best of our knowledge, this is the first solar cell based on cast-mono material that exceed 23% efficiency. This gives scope that cast materials may still be used in future cell fabrication because such high efficiencies and lower cost may offset the lower production yield compared to Czochralski (Cz) wafers. We report on details about our cell structure and processing, we analyze the bulk lifetime before and after cell fabrication, and give details about the optimization of the rear passivating contact. • We demonstrate TOPCon cells with a best efficiency of 23.22% on large-area quasi-mono wafers. • We analyses the bulk lifetime before and after cell fabrication. • We give details about the optimization of the rear passivating contact. [ABSTRACT FROM AUTHOR]

We demonstrate an "industrial tunnel oxide passivated contacts" (i-TOPCon) silicon solar cell on large area n-type silicon wafers (156.75 mm × 156.75 mm). This cell has a boron diffused front emitter, a tunnel-SiO x /n+-poly-Si/SiN x :H structure at the rear side, and screen-printed electrodes on both sides. The passivation of the tunnel-SiO x /n+-poly-Si/SiN x :H structure on silicon wafers is investigated. The saturation currents J o of this structure on polished and textured silicon surfaces are 1.3 and 3.7 fA/cm2, respectively. After printing the Ag contacts, the J o of this structure increases to 50.7 fA/cm2 on textured silicon surfaces, which is still manageably low for metal contacts. This structure was applied to i-TOPCon solar cells, resulting in a median efficiency of 23.91%, measured in-house, and a champion efficiency of 24.58%, independently confirmed by the ISFH CalTeC in Germany. The champion efficiency was measured with total area illumination, including screen-printed fingers and busbars. Image 1 • We demonstrate i-TOPCon cells with a best efficiency of 24.58% on 156.75 mm × 156.75 mm. • The tunnel-SiO x /n+-poly-Si films on wafers show an excellent contact passivation. • Major power losses are in the emitter, including its bulk, surface, metal contacts. [ABSTRACT FROM AUTHOR]