Photoinduced Anisotropic Supramolecular Assembly and Enhanced Charge Transport of Poly(3‐hexylthiophene) Thin Films

Abstract

The self‐organization of organic polymer semiconductors into ordered supramolecular assemblies commensurate with efficient charge transport is achieved by tuning a range of process parameters (e.g., film deposition method (spin vs drop cast), solvent boiling point (low vs high boiling point), polymer‐dielectric interface treatment, and post‐deposition processing (solvent vapor or thermal annealing)). However, these strategies present limitations for large‐scale high‐throughput processing due to associated pre‐ and/or post semiconductor deposition steps. Here, photoinduced anisotropic supramolecular assembly of P3HT chains in solution is demonstrated. UV irradiation provides for enhanced intramolecular ordering of solubilized polymer chains, and thereby effects formation of anisotropic supramolecular polymer assemblies via favorable π–π stacking (intermolecular interaction). Molecular ordering is thus dramatically enhanced with concomitant, enhanced charge transport characteristics of corresponding films. Additional pre‐ and/or post treatments are avoided.

The effect of intermolecular interaction on excited states in p − DTS(FBTTH2)2

“…A more compelling explanation is that an increasing planarization, resulting from the freezing out of torsional dynamics, reduces the solubility of the molecule in the solvent, so that a reduced solvation dynamics assists the formation of aggregates. 28,35 A further illuminating aspect in this comparison of the disorder-order transition between π-conjugated polymers and molecules consists in the remarkable sharpness of the transition observed in Figure 3d. For commercial MEH-PPV or P3HT samples with polydispersity indices (PDIs) exceeding 2, the disorder-order transition is smeared out over a large temperature range, so that their temperature dependence resembles a second order phase transition.…”

Highly anisotropic P3HT films with enhanced thermoelectric performance via organic small molecule epitaxy

“…17,18 Poly(3-hexylthiophene) (P3HT) is another promising candidate as a TE material, especially with its higher solubility in common organic solvents and highly tunable molecular structure and molecular weight compared with poly(3,4-ethylenedioxythiophene). [19][20][21][22][23][24][25] Interest in P3HT as a TE conversion material has increased since 2010. [26][27][28][29] However, the TE properties of pure P3HT are still unsatisfactory at present, with a power factor of o20 μW mK À2 .…”

Improvement of the photovoltaic properties for P3HT:PCBM system annealed at the temperature in liquid crystalline regions induced by liquid crystal molecules

“…The exciton band bandwidth (W) correlates with the conjugation length of an individual polymer chain. The decrease in W value shows an increase of both average conjugation length and chain order [34,35]. The W values could be calculated by the following equation:…”