Full efficiency recovery in Hole Transporting Layer-free Perovskite Solar Cells with free-standing dry-carbon top-contacts

Carbon-based top-electrodes for Hole-Transporting-Layer-free Perovskite Solar Cells (PSCs) were made by hot-press (HP) transfer of a free-standing Carbon-Aluminum foil at 100°C and pressure of 0.1MPa on a Methylammonium Lead Iodide (MAPbI3) layer. Under these conditions, the perovskite surface is preserved from interaction with the solvent. HP-PSCs have been systematically compared, along a time-scale of 90 days, to reference cells having Carbon-based top electrodes deposited by doctor blading (DB). We found that all the photovoltaic parameters recorded in HP-PSCs during time under ambient conditions settle on values systematically higher than those measured in the reference DB-PSCs, with efficiency stabilized at around 6% within the first few measurements. On the opposite side, in DB-PSCs, a long-lasting (~14 days) degrading transient of the performances is observed with a loss of efficiency