The Solar Energy Research Institute of Singapore at the National University of Singapore has published research on heated indium tin oxide (ITO) depositions for perovskite silicon tandem solar cells. The study focused on double sided (DS) thin polysilicon (poly-Si) tunnel oxide passivated contacts (TOPCon) used as the silicon bottom cell. Limited lateral conductivity in thin poly Si layers typically requires a transparent conductive oxide layer deposited by sputtering. Conventional sputtering can damage passivation quality in DS TOPCon structures. The researchers proposed heated ITO deposition and in situ annealing to reduce sputtering damage while improving film properties. High temperature deposition enhanced transparency and carrier mobility without significantly degrading poly Si passivation. Using M2 sized 244 cm² DS TOPCon bottom cells with 1-Sun efficiencies up to 16.7%, the team fabricated 16 cm² planar tandem cells reaching 22.1%.