Engineering a Conformal and Lossless Interconnect via Ultrathin ITO for High‐Efficiency Perovskite/Silicon Tandem Solar Cells

ABSTRACT Monolithic perovskite/silicon tandem solar cells are highly attractive due to their potential for high power conversion efficiency (PCE). In tandem solar cells, the perovskite top cell and silicon bottom cell are connected via a recombination layer, and the quality of this interface directly affects carrier transport and recombination. However, in silicon heterojunction (SHJ) cells–particularly on micro‐pyramidal (∼600 nm‐thick) textured surfaces, optical losses in the composite layer and non‐uniform coverage of the self‐assembled monolayer (SAM) remain challenging. Here, we investigated the optoelectronic properties of indium tin oxide (ITO) composite layers with thickness ranging from 2 to 30 nm, by optimizing the intermediate composite layer, optical losses in perovskite/silicon tandem solar cells were effectively reduced, and surface potential uniformity was enhanced. We selected an ultra‐thin (8 nm‐thick) ITO layer modified with nickel oxide (NiO x ), which was implemented as a composite interconnect, with a Poly‐SAM layer employed to realize these enhancements. Compared to the reference thickness, the optimized device exhibited an increase in short‐circuit current density of 0.85 mA cm −2 , achieving a high value of 20.82 mA cm −2 , and a power conversion efficiency of 31.80 % was achieved, and 96 % of the initial PCE was retained after 500 h of maximum power point tracking.