Solvent effects and multiple aggregate states in high-mobility organic field-effect transistors based on poly(bithiophene-alt-thienothiophene)

Abstract

Franck–Condon absorption analysis reveals the existence of several aggregate states in poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT) thin films which impact their recrystallization and the attainable field-effect mobility (μFET). Poor solvents (toluene and mixed-xylenes) lock in both disordered and well-ordered states that cannot be annealed away even in the liquid crystalline phase. This reduces μFET and increases mobility activation energies compared with films from good solvents (chlorobenzene and o-dichlorobenzene). Despite its poor solubility characteristics, PBTTT can be ink-jet printed in dilute chlorobenzene, and devices can be operated unencapsulated in ambient, in the dark (>105cycles over several days) with only a moderate mobility loss.

Microstructural Characterization and Charge Transport in Thin Films of Conjugated Polymers

“…We conclude that these models provide extremely useful information about the amount of disorder in the material and the microstructural lengthscales, which affect charge transport. A somewhat similar analysis based on Franck–Condon progressions, although not to the same level of detail achieved in P3HT, was recently attempted on PBTTT thin films 87. Up to four absorption states were postulated and their appearance was linked to thermal treatments and deposition solvent.…”

Controlling the Surface Organization of Conjugated Donor–Acceptor Polymers by their Aggregation in Solution

“…For instance, the solution aggregation of a copolymer based on naphthalene‐diimide (NDI) was tuned by using various solvents leading to a distinct variation in domain morphologies and charge‐carrier mobilities . The organization in thin films of poly(2,5‐bis(3‐alkylthiophen‐2‐yl)thieno[3,2‐ b ]thiophene) (PBTTT) also strongly depends on its solubility . Ordered structures with high mobilities are primarily created from good solvents, while poor solvents generate both ordered and disordered states.…”

Transferred metal electrode films for large-area electronic devices

“…We illustrate here for the FET semiconductor an organic semiconductor, a 30-nm-thick C 14 -PBTTT polymer layer, 10,11 although oxide or quantum dot semiconductors could also be used. In a typical fabrication, SC-1 cleaned glass substrates were patterned with 30-nm-thick Au source and drain electrodes with a 7-nm-thick Cr adhesion layer.…”