High‐Mobility Self‐Assembling Truxenone‐Based n‐Type Organic Semiconductors

Abstract

The synthesis, self-assembly, and semiconducting properties of a series of disk-like truxenone derivatives, functionalized with three peripheral long alkyl chains, either directly attached or distanced by linking phenyl or ethynyl groups, are reported. The strategy of distancing the alkyl chains from the central aromatic cores induces in these discotics well-ordered columnar assemblies and has a favorable effect on their charge-carrier mobility. Electron mobility values above 1 cm V S were determined for a truxenone functionalized with three peripheral decynyl chains by means of the space charge-limited current technique. DFT calculations help to rationalize the high mobility values found for these new truxenone-based systems, indicating efficient intermolecular electronic couplings (fostered by a favorable stacking configuration) and moderate intramolecular reorganization energies for electrons in the origin of such high mobilities.

In silico design of 2D polymers containing truxene-based platforms: insights into their structural and electronic properties

“…However, it is worth noting that AB stacking is the preferential stacking configuration for the A-Tr and A-Tx systems, while the A-To compounds prefer to stack in AA fashion. Interestingly, these results are in good accordance with the available X-ray data reported for triindole 18,59,60 (truxenone) 21 cores in selfassembling systems, where a preferential staggered (eclipsed) stacking conformation of the cores is adopted for which large electronic couplings are obtained. This favourable electronic coupling between the cores of the adjacent layers may increase the bandwidth along the vertical direction and probably explains the high carrier mobility of the experimentally obtained Ph-Tr 2 16 despite the flat bands predicted for the T 2 and T 3 single-layer COFs.…”

“…Varying the nature of the bridging groups (i.e., changing methylene units to amino or ketone units) allows us to obtain molecules that share the truxene-like geometry but show completely different redox and semiconducting behaviors. Thus, while triindole 18,19 and truxene 20 are p-type semiconductors, truxenone 21 behaves as a high-mobility n-type semiconductor.…”

Charge Mobility in Discotic Liquid Crystals

“…DLC that show high electron conduction are not too common. An interesting example is represented by the truxenones derivatives studied by Gomez-Esteban and coworkers [213]. A SCLC mobility of about 1 cm 2 •V −1 •s −1 was reported for compounds 55 and 56, while it was two orders of magnitude lower for compound 57 (Figure 34).…”

“…DFT and semiclassical Marcus theory were used to predict mobility values that are very close to the measured mobility for compounds 55 and 56, while the same agreement was not found in the case of 57. The lower mobility measured in 57 and the difference with the theoretically predicted mobility cannot be explained in terms of intrinsic molecular factors and, therefore, they were attributed to a decrease in intra-stack order when alkyl chains are linked directly to the core [213]. Ambipolar compounds were widely studied because they can be used in several applications.…”

“…Besides triphenylene, other molecular systems were studied in recent years, such as those based on triindole [208,209], phthalocyanine [125,210], thiophene [211,212] and truxenone [213,214] cores, or on particular molecular architectures, such as dendrons [174,176,215,216]. Nakawa and coworkers reported the study of the mesomorphic and mobility properties of a blend of 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2) with its analogue 1,4,8,11,15, 18,22,25octahexyltetrabenzotriazaporphyrin (C6TBTAPH2) [125].…”