Scanning tunneling microscopy (STM) of monolayers comprising oligothiophene and fullerene molecular semiconductors reveals details of their molecular-scale phase separation and ordering with potential implications for the design of organic electronic devices, in particular future bulk heterojunction solar cells. Prochiral terthienobenzenetricarboxylic acid (TTBTA) self-assembles at the solution/graphite interface into either a porous chicken wire network linked by dimeric hydrogen bonding associations of COOH groups (R(2)(2) (8)) or a close-packed network linked in a novel hexameric hydrogen bonding motif (R(6)(6) (24)). Analysis of high-resolution STM images shows that the chicken wire phase is racemically mixed, whereas the close-packed phase is enantiomerically pure. The cavities of the chicken wire structure can efficiently host C60 molecules, which form ordered domains with either one, two, or three fullerenes per cavity. The observed monodisperse filling and long-range co-alignment of fullerenes is described in terms of a combination of an electrostatic effect and the commensurability between the graphite and molecular network, which leads to differentiation of otherwise identical adsorption sites in the pores.

Terthienobenzene (TTB, 6) was prepared through a new, high yield route along with pi-extended derivatives 10 and 11. Electropolymerization of tris-EDOT derivative 11 results in a highly stable cross-linked conjugated polymer that shows polaron confinement between the TTB units as confirmed by UV-vis-NIR spectroelectrochemistry and EPR.

Reported here are the unique properties of N,N 0 ,N 00 -(3,4,5-tridodecyloxyphenyl)benzo[b,b 0 , b 00 ]tristhiophene-2,2 0 ,2 00 -tricarboxamide 3 as a new H-bonded discotic liquid crystal. Polarized optical microscopy and thermal analysis as well as variable temperature IR spectroscopy and X-ray diffraction confirm the presence of two thermotropic H-bonded hexagonal columnar mesophases that cover a temperature range from <-50 to 280 °C. Intermediate lyotropic mesophases of the highly viscous material aid the alignment of the hexagonal columnar mesophases, which is essential for a detailed structural characterization and applications. Solutions of 3 in heptane at concentrations as low as 1 wt % display isotropic organo-gel phases that consist of H-bonded networks of 3 but do not contain columnar stacks. 2D-X-ray diffraction studies on aligned samples of the thermotropic hexagonal columnar mesophases and DFT calculations on a tetramer of 3 reveal a helical columnar stacking of the individual benzotristhiophene units. Charge carrier mobility measured by time-resolved microwave conductivity is about 0.02 cm 2 V -1 s -1 in both hexagonal columnar mesophases and quasi temperature independent even across the phase transition between the two mesophases. The temperature independence is explained by the interrelation between stacking distance and mutual rotation because of the persistent intracolumnar H-bonds between amide groups. Half-life of the charge carriers, on the other hand, drastically increases in the low temperature hexagonal columnar mesophase, which is most likely a result of changing molecular dynamic and conformational states of the side chains. DFT calculations of the frontier orbitals show that the benzotristhiophene core is the sole contributor to the LUMO but does not contribute to the HOMO, whereas the trialkoxyaniline groups are the sole contributors to the HOMO. This suggests that the observed combined mobility is that of electrons alone because no hole transport is expected to occur between trialkoxyaniline groups that are spaced apart by more than 4 A ˚. Indeed, an electron mobility of 2 Â 10 -3 cm 2 V -1 s -1 but no transient signal for hole transport is obtained by timeof-flight charge carrier mobility measurements on a multi domain sample of 3.