Vacuum-assisted annealing method for high efficiency printable large-area polymer solar cell modules

Abstract

In general, the power conversion efficiencies (PCEs) of blade-coated polymer solar cells (PSCs) are low compared with those of spin-coated PSCs. In this study, a simple and effective vacuum-assisted annealing method has been developed to optimize the morphology of the blade-coated active layer processed by the same processing solvents as those used in spin coating. The blade-coated blend films are annealed with the assistance of a vacuum (∼10⁻¹ Pa), and the corresponding device shows photovoltaic performance comparable to that of the devices fabricated by spin coating. The vacuum-assisted annealing method works well in blade coated PSCs based on a series of representative photoactive blend systems using the optimized solvents from the spin-coating method. For instance, for the blade-coated with the PBDB-TF:IT-4F blend film, the device exhibits a PCE of 13.6%, which is not only as good as the spin-coated device but also the highest value for the PSCs made by the blade coating method. More importantly, the vacuum-assisted annealing method can be successfully applied in fabricating a large-area device module with an active area of 12.6 cm², and the device achieves a high PCE of 10.21%.