Investigation of in situ annealing on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate): towards all-solution-processed inverted polymer solar cells
Efficient spray-coated inverted polymer solar cells (PSCs) based on a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transport layer (HTL) are investigated by incorporating an in situ annealing treatment. Compared to conventional annealed devices, the in situ annealed PSCs exhibited a 25.5% and 47.7% enhancement in fill factor and power conversion efficiency (PCE) respectively, as well as about a two-fold improvement in the device lifetime. The performance enhancement was attributed to the improvement of the vertical phase separation of the PEDOT:PSS HTL and the reduction of the residual humidity of the HTL. This approach significantly enhances our understanding of the application of the PEDOT:PSS HTL in inverted PSCs, and illuminates the potential of spray coating for the sustainable commercial fabrication of PSCs with high PCEs.