Alcohol based vapor annealing of a poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) layer for performance improvement of inverted perovskite solar cells

In this study, we introduced alcohol based vapor annealing of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer for fabricating high-performance inverted perovskite solar cells. Atomic force microscopy measurements and atomistic theoretical simulations indicated that phase separation between PEDOT and PSS was enhanced by this annealing, improving the hole conductivity at the PEDOT:PSS layer. As a result of using methanol, the short-circuit current density improved from 20.7 to 21.6 mA cm(-2); consequently, the power conversion efficiency (PCE) improved from 16.1 to 17.3%. However, using ethanol or isopropanol yielded a smaller performance improvement. The PCEs of the best sample in this study under forward and reverse scans were 17.7 and 18.0%, respectively, indicating that the PSC had a small hysteresis. Our results suggest that alcohol vapor annealing is a simple and effective method of developing high-performance inverted perovskite solar cells.