Efficient, stable and low-cost hole transporting layer for Perovskite solar cells

Among the new generation photovoltaic (PV), Perovskite solar cell technology reached top efficiencies in a few years. Researchers should achieve stability and process/material low cost to place the technology in the market. Among the different layers that compose a Perovskite solar cell, the hole transporting layer (HTL) plays a crucial role in terms of efficiency and stability. The reference and expensive Spiro-OMeTAD HTL has high efficiency but poor stability. The main scope of this work is to optimize the process to obtain efficient, repeatable and stable devices, by using the low cost and scalable X55 HTM (hole transporting material) that is emerging in the Perovskite solar cell field. We show a champion efficiency about 16% that is higher respect to the reference Spiro-OMeTAD case (about 15%). The results are also confirmed by IPCE spectra. Finally, we demonstrate for the first time in literature the stability of the material in humidity condition.