Morphology control via dual solvent crystallization for high-mobility functionalized pentacene-blend thin film transistors

Abstract

We present an approach to improving the performance of solution processed organic semiconductor transistors based on a dual solvent system. We here apply this to a blend containing the p-conjugated small molecule 6,13 bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) and polystyrene, which acts as an inert binder. Using a semiconductor-binder solution of two solvents, where the main solvent is a better solvent of the small molecule and second solvent is a better solvent of the polymer, crystal morphologies can be altered and transistor mobilities increased by almost an order of magnitude. In this way, air-ambient and solution-processed transistors with linear and saturation mobilities higher than 1 cm 2 V À1 s À1 have been fabricated. We discuss how the solubility properties of the formulation components can be used to identify solvent candidates that promote an efficient self-assembly of the small molecule.

Temperature gradient approach to grow large, preferentially oriented 6,13-bis(triisopropylsilylethynyl) pentacene crystals for organic thin film transistors

“…Note that during TIPS pentacene crystal growth, solvent annealing with toluene was employed to increase the individual crystal size, as well as the quality. [12][13][14] In a solvent-rich environment, the solvent evaporation is slowed down, which allows more time for crystals to develop in size and quality. 15,16 Large crystals reduce the gaps between each other, and thus enhance the areal coverage.…”

Highly sensitive broadband flexible photodetectors based on a blend film with zinc octaethylporphyrin long nanowires embedded in an insulating polymer

“…19,20 They have been used as the active layers of organic thin film transistors (OTFTs), which are to fabricate low-voltage driven devices, to improve ambient stability, and to reduce consumption of materials. 19,20 They have been used as the active layers of organic thin film transistors (OTFTs), which are to fabricate low-voltage driven devices, to improve ambient stability, and to reduce consumption of materials.…”

Homogeneous Crystallization of Micro-DispensedTIPS-Pentacene Using a Two-Solvent System toEnable Printed Inverters on Foil Substrates

“…Lim et al, have furthered the understanding of the relationship between the film morphologies and crystallization due to a two-solvent drying process [11]. Additionally, the research group of Maria Lada et al have also published a method to increase the mobility of TIPS-pentacene via a dual solvent crystallization process [12]. Similarly, Gil Jo Chae et al have also focused on improved performance in TIPS-pentacene using solvent additives such as diphenyl ether (DPE) or chloronaphthalene (CN) [13].…”

“…This is evident also as thick rings at the edges of the drop, commonly referred to as the "coffee-stain" effect [14,15]. The starting point is the research done by research groups [11][12][13][14]16,17] to solve this problem by use of a mixed solvent system. By using a mixed solvent system besides the existence of a convective flow in the drying droplet, there is the creation of a Marangoni flow due to the difference in boiling points and surface tension of the solvents.…”