Fig. 3

AFM phase images of dry-annealed PEDOT:PSS free-standing films. a Pristine PEDOT:PSS film. b–f Dry-annealed pure PEDOT:PSS films prepared by adding different amount of DMSO by b 5 vol.%, c 13 vol.%, d 20 vol.%, e 33 vol.%, and f 50 vol.%. Note that vol.% indicates the volume fraction of the added DMSO to the final solution volume. The measured surface roughness is a 1.6 nm, b 1.4 nm, c 2.5 nm, d 2.0 nm, e 2.1 nm, and f 3.1 nm. Scale bars, 100 nm