Interdigitated back contacted c-Si(p) solar cells with photovoltaic efficiencies beyond 22%

In this work we show a baseline fabrication process of interdigitated back contacted IBC c-Si(p) solar cells, which combines conventional diffusion oven stages to define base p+ and emitter n ⁺ /n ⁺⁺ regions at the back side, with outstanding front surface passivation using atomic layer deposited Al ₂ O ₃ films over random pyramids surfaces. Cells include a selective phosphorous n ⁺⁺ emitter in order to improve contact resistance and simultaneously reduce recombination current density. Fabricated devices reach efficiencies up to 22.2% (AM1.5G 1 kW/m ² , T=25°C). This value is so far the highest efficiency reported by any Spanish institution using silicon substrates. 3D simulations envisage efficiencies beyond 24% introducing little changes in the fabrication process.