Indium-free perovskite/silicon tandem solar cells with tin oxide recombination layer and electrodes

Indium-based transparent conductive oxides are widely used as electrodes and recombination layers in perovskite/silicon tandem solar cells, yet their scalability is constrained by indium scarcity and sputtering-induced damage. Here we report high efficiency and stable indium-free perovskite/silicon tandem solar cells enabled by reactive plasma deposited tin oxide (RPD-SnO_x). For RPD-SnO_x as the recombination layer, a certified efficiency of 33.6% is achieved. Fully indium-free tandems that used RPD-SnO_x as both recombination layer and electrodes delivering a champion PCE of 33.2% (1 cm²) and a mini-module with a certified efficiency of 31.0% (207.9 cm²). Dense and uniform self-assembled monolayer anchoring enabled by RPD-SnO_x suppressed non-radiative recombination and reduced halide migration. Indium-free mini-modules exhibited high thermal, damp-heat, and outdoor operational stability and retained 65% of their maximum initial efficiency after 105 days of outdoor operation.