Achieving 20% Efficiency for Low-Temperature-Processed Inverted Perovskite Solar Cells

Low-temperature-processed inverted perovskite solar cells (PVSCs) attract increasing attention because they can be fabricated on both rigid and flexible substrates. For these devices, hole-transporting layers (HTLs) play an important role in achieving efficient and stable inverted PVSCs by adjusting the anodic work function, hole extraction, and interfacial charge recombination. Here, the use of a low-temperature (<= 150 degrees C) solution-processed ultrathin film of poly[(9,9-dioctyl-fluorenyl-2,7-diyl)-co-(4',4'-(N-(4-secbutylphenyl) diphenylamine)] (TFB) is reported as an HTL in one-step-processed CH3NH3PbI3 (MAPbI(3))-based inverted PVSCs. The fabricated device exhibits power conversion efficiency (PCE) as high as 20.2% when measured under AM 1.5 G illumination. This PCE makes them one of the MAPbI(3)-based inverted PVSCs that have the highest efficiency reported to date. Moreover, this inverted PVSC also shows good stability, which can retain 90% of its original efficiency after 30 days of storage in ambient air.