Solution-processed small molecule transistors with low operating voltages and high grain-boundary anisotropy

Late stage crystallization and healing during spin-coating enhance carrier transport in small-molecule organic semiconductors

“…In recent years, solution-processed small-molecule organic thin-lm transistors (OTFTs) have achieved eld-effect mobilities well in excess of 1 cm 2 V À1 s À1 , with some reports of eld effect mobilities above 10 cm 2 V À1 s À1 . [1][2][3][4][5] Such transistor mobilities increasingly surpass those of the best OTFTs prepared via vacuum evaporation and also the performance of hydrogenated amorphous silicon devices by nearly an order of magnitude. 6,7 The characteristics of solution-processed OTFTs can vary dramatically depending on the solution processing conditions, especially in the case of small-molecule organic semiconductors, since thin lm nucleation and crystallization are highly sensitive to solution drying kinetics.…”

Bistetracene Thin Film Polymorphic Control to Unravel the Effect of Molecular Packing on Charge Transport

“…In total, over 200 devices were measured, and by plotting the mobility versus the grain orientation, a clear angular dependence of the mobility within bistetracene solvent‐annealed films is shown in Figure . The mobility of the films in which the grains were oriented perpendicular to the channel were on average 12 times lower than that of the parallel grain orientation, much larger than the anisotropy value of 3.4 from the transfer integral calculations, similar to mobility anisotropy measurements of single crystals, demonstrating the role of grain boundaries at this channel length (50 µm) . Yet, this mobility anisotropy compares well to the benchmark 2D brick‐layer packing small molecule, TIPS‐pentacene, which in the solution processed crystalline thin film exhibits mobility anisotropy on the order of 7.5–10 …”

Solution-processing of semiconducting organic small molecules: what we have learnt from 5,11-bis(triethylsilylethynyl)anthradithiophene

“…This is surprising as similar molecules often exhibit at least a two-fold difference in transport along different molecular packing directions. [31][32][33] Clearly, this is a highly desirable attribute, especially if such TES ADT architectures were to be integrated into electronic circuits. The size of the spherulites or grains plays, however, an important role.…”