Figure 4: PCDTBT thin-film diffraction pattern, unit cell and bilayer motif.
(a) Diffraction pattern obtained from the Bragg peaks shown in Fig. 2d. The filled circle corresponds to the origin. (b) The corresponding oblique real-space lattice obtained from the scattering pattern. The π–π direction is normal to this plane. (c) Undulating backbone configuration for one of possible conformations of a backbone obtained by ab initio calculations (Fig. 5c). The second chain is merely a rotated/translated copy of the first one. Including the full interactions would provide further adjustment in the positions perpendicular to the backbone. The alkyl chains (C8H17) are denoted by R for simplicity and occupy the blue-shaded region. This is the same oblique unit cell shown in (b). (d) A three-dimensional illustration of the crystalline phase where the red trapezoid identifies the 2D unit cell.
