Tuning crystal polymorphs of a π-extended tetrathiafulvalene-based cruciform molecule towards high-performance organic field-effect transistors

Abstract

It is a common phenomenon for organic semiconductors to crystallize in two or more polymorphs, leading to various molecular packings and different charge transport properties. Therefore, it is a crucial issue of tuning molecular crystal polymorphs (i.e., adjusting the same molecule with different packing arrangements in solid state) towards efficient charge transport and high performance devices. Here, the choice of solvent had a marked effect on controlling the growth of α-phase ribbon and β-phase platelet during crystallization for an indenofluorene (IF) π-extended tetrathiafulvalene (TTF)-based cruciform molecule, named as IF-TTF. The charge carrier mobility of the α-phase IF-TTF crystals was more than one order of magnitude higher than that of β-phase crystals, suggesting the importance of reasonably tuning molecular packing in solid state for the improvement of charge transport in organic semiconductors.

Crystallization Mechanisms Applied to Understand the Crystal Formation of Rotaxanes

“…In the crystalline state, molecule organization is intimately related to their properties, i.e., differences in crystal packing can change their physical properties (e.g., luminescence) . The study of crystal packing is already widely explored in small molecules,, cocrystals,, and polymorphs, being described by different approaches, such as motifs with geometric data (distances and angles).…”

High-performance five-ring-fused organic semiconductors for field-effect transistors

“…However, organic field-effect transistors based on thin films or single crystals of some IF derivatives were reported recently. 90,105–133 For example, the hydrogen atoms of the 2- and 8-positions are replaced with two thiophene units (DTIF, 002 , Fig. 3), and vacuum deposited thin films of DTIF present a hole mobility of 10 −2 cm 2 V −1 s −1 .…”

Indenofluorenes for organic optoelectronics: the dance of fused five- and six-membered rings enabling structural versatility

“…However, there has been a very limited report on this to date. In the only known report to our knowledge, Dong et al 88 studied the single crystal-based OFETs of a TTF-functionalized IF molecule, IF-TTF-2 (Fig. 10).…”