Thermotropic Behavior, Packing, and Thin Film Structure of an Electron Accepting Side-Chain Polymer

Abstract

We report on the phase behavior and the structure of poly(perylene bisimide acrylate), an electron accepting semiconductor polymer with disclike side-chain units, in comparison to the corresponding low molecular weight perylene bisimide. By combination of DSC, optical microscopy, and temperature-dependent small-angle and wideangle X-ray scattering, we show that both compounds display a lamello-columnar packing. While the perylene bisimide model compound crystallizes, the polymeric architecture of poly(perylene bisimide acrylate) suppresses order, leading to a 2D lamello-columnar liquid crystalline phase. The structure of the side-chain polymer in thin films with different thermal treatments as observed by GIWAXS correlates well with previously observed largely different electron mobilities. Such a polymeric, liquid crystalline compound combines the advantages of molecular order and easy processability, together with the film forming properties of polymeric materials.

N‐Type Self‐Assembled Monolayer Field‐Effect Transistors and Complementary Inverters

“…We note that the weak crystallinity can be inferred from X-ray diffraction studies on bulk branched perylene derivatives. [20][21][22] The packing of alkyl terminated PBI-PA based molecules is dominated by the interaction between the conjugated PBI-PA cores. The π -π stacking of the aromatic cores leads to parallel stacks with a typical distance of 0.36 nm.…”

Avoiding Bias Effects in NMR Experiments for Heteronuclear Dipole–Dipole Coupling Determinations: Principles and Application to Organic Semiconductor Materials

“…The rotor period was then completed by heteronuclear decoupling by using two-pulse 13 C CP spectra (top) and the corresponding DIPSHIFT intensity modulation curves (bottom right, see also Figure 2) recorded at 4 kHz MAS detected at the aromatic CH resonance of perylene bisimide (PBI), an electron-accepting molecular unit for photovoltaic applications. [15] For long CP times t CP , signal overlap of the aromatic CH signals with signals from quaternary carbon atoms leads to nonspecific modulation curves and systematic errors. In contrast, short CP times, used to successfully isolate the aromatic CH resonance, lead to strongly distorted modulation curves, precluding a simple analysis by a fit to the known theoretical formula.…”

“…The PBI aromatic core forms columnar stacks, and the packing (ordering) and dynamics of the core are sensitive to the nature of the aliphatic substituents. [15,[28][29][30] The p-p orbital overlap of the stacked cores leads to one-dimensional charge carrier mobility and explains the semiconducting properties of these materials, which render them suitable candidates for photovoltaic applications. [31] Attaching the asymmetrically substituted PBI side-on to an acrylic polymer chain (PPerAcr), and possibly attaching another copolymer block, allows for easy device fabrication by spin casting and subsequent self-assembly upon annealing.…”

“…This is highlighted in Figure 1 for the spectra of a perylene bisimide (PBI) derivative, an organic semiconductor molecule for photovoltaic applications. [15] In the corresponding study we were interested in correlating the (liquid-) crystalline phase structures formed by PBI and its side-chain polymer analogue with the corresponding aromatic core mobilities, as probed by the aromatic CH groups, but we could not obtain quantitative results due to signal overlap. For commonly long CP times, the DIPSHIFT modulation curve of the CH peak of interest is biased by underlying contributions of weakly coupled quaternary carbon atoms.…”

“…In the last part we present as an application the results of the measurement of dynamic order parameters quantifying the aromatic core mobility in PBI and a polymeric analogue at different temperatures, and correlate these findings with the known phase structures. [15] …”