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Abstract—Unlike the traditional tube-furnace annealing at 875 °C, rapid thermal annealing (RTA) and laser annealing offer flexibility, high throughput, and control of the heating and cooling rates and holding times for effective crystallization, dopant activation, and passivation quality in the B-doped p-TOPCon device. A comprehensive scientific understanding of the effects of RTA is required. Slower RTA heating (≤ 798 K/min) and cooling (≤ 156 K/min) rates and optimal 60 s holding time at 825 °C enhanced the passivation quality, which was further improved by post anneal forming gas annealing (FGA). Faster heating and cooling rates (≥ 4800 K/min) damaged the passivation quality irreversibly and did not improve further by FGA. The optimized RTA parameters yielded iVoc of 638 mV and sheet resistance of ∼1.0 kΩ/sq. The dopant activation was independent of the heating and cooling rates. 

The rapid rise in single-junction perovskite solar cell (PSC) efficiencies, tunable bandgap and low-cost solution processability make PSCs an attractive candidate for tandems with Si bottom cells. However, the challenge is to fabricate a high-performance semitransparent perovskite top cell in combination with an appropriate silicon bottom cell with high response to long wavelength photons that are filtered through the perovskite top cell. Currently, semitransparent perovskite cells show much lower performance compared to their opaque counterparts while high-performance silicon bottom cells, such as heterojunction with intrinsic thin layer (HIT) and interdigitated back contact (IBC), maybe too expensive to meet the cost and efficiency targets for commercial viability. Here, we demonstrate a 26.7% perovskite-Si four terminal (4T) tandem cell comprising a highly efficient 17.8% CsFAMAPbIBr semitransparent, 1.63-eV bandgap perovskite top cell and a ≥ 22% efficiency n-type Si bottom cell fabricated with a conventional boron diffused emitter on the front and carrier selective n+ poly-Si/SiOx passivated contact on the rear. This is among the highest efficiency perovskite/Si 4T tandems published to-date and represents the first demonstration of the use of the high temperature-resistant single side n-TOPCon Si cell in a 4T configuration.