Fig. 2
From: Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors
Angle-dependent charge transport at room temperature for Cl2-NDI single crystals with different thicknesses. a Optical micrograph of Cl2-NDI vacuum gap FETs for mobility anisotropy measurement. A fan-shaped contact pattern was employed to probe transport in different angular directions. 0° corresponds to the [110] direction and the crystal long-axis. b Crystal packing structure (left, CH2C3F7 omitted for clarity and black dashed lines represent π–π intermolecular interactions) and schematic diagram of crystal steps (blue dashed lines) on the (001) crystal facet (right). Crystal steps are almost perpendicular to the [110] direction. c, d Mobility and VT anisotropy, respectively, for Cl2-NDI devices with different crystal thicknesses. Inserted percentages on the mobility polar plot in c represent mobility degradation [(μthin−μthicker)/μthin] in the respective directions
