Charging rate image of a polymer blend lm. a, AFM height image of a 50:50 lm of F8BT/PFB spin coated from xylenes. The recessed domains are enriched in PFB (lm thickness: 90 nm). (Right) EFM photoinduced charging rate map generated by plotting the inverse exponential time constant for photoinduced charging at each point in left image. The dark rings indicate regions of slower charging. Imaged with the MFP-3D AFM. Image courtesy of D. Coffey and D. Ginger, Univ. of Washington. Referenced 13 August 2006; doi:10.1038/nmat1712.