Crystal structures of two rubrene derivatives

FIG. 2: Perspective views of the structures of 5,11-BTBR (polymorph A, left), rubrene (center), and 5,12-BTBR (similar to 5,11-BTBR B, right). For clarity, only one layer of molecules with respect to the paper plane is shown. a) View onto the a-b face: In rubrene and 5,12-BTBR (5,11-BTBR B), π-stacking between the molecules is established along a (short axis), whereas in 5,11-BTBR (A) the spacing between the backbones is twice as wide in the equivalent direction of b. b) View along a or b, respectively, illustrates the molecular layers. In the single crystal FETs the current flows along the layers in the a-b direction (in-plane), while in the TD-SCLC measurements the current flows in direction of c or c⋆, respectively, i.e. perpendicular to a,b.