In organic thin film transistors (OTFT), the morphology and microstructure of an organic thin film has a strong impact on the charge carrier mobility and device characteristics. To have well-defined and predictable thin film morphology, it is necessary to adapt the basic structure of semiconducting molecules in a way that results in an optimum crystalline packing motif. Here we introduce a new molecular design feature for organic semiconductors that provides the optimized crystalline packing and thin film morphology that is essential for efficient charge-carrier transport. Thus, cyclohexyl end groups in naphthalene diimide assist in directing intermolecular stacking leading to a dramatic improvement in field effect mobility. Accordingly, OTFT devices prepared with vapor deposited N,N′-bis(cyclohexyl) naphthalene-1,4,5,8-bis(dicarboximide) (1) regularly exhibit field effect mobility near 6 cm2/(V s), which is one of the highest carrier mobilities reported for either n- or p-type organic semiconducting thin films.

This paper describes a series of thiophene-based conjugated polymers that become insoluble upon irradiation with ultraviolet light. Stille or Suzuki reactions of appropriately substituted 2,5-bromothiophene derivatives yielded terthiophene and polythiophene derivatives with either o-nitrobenzyl (ONB) ester or ONB ether photolabile side chains with n-octyl substituents. Light-induced cleavage of these ONB side chains with ultraviolet light at 365 nm cleaves the octyl chains responsible for solubilization of the polymers away from the conjugated main chains, rendering them insoluble. Consistent with the accepted mechanism of ONB photolysis, those structural modifications that would yield a more stable benzylic radical methyl substitution on the benzylic position, replacement of the ester with an ether, or bothyielded more efficient photolyses as determined by (i) quantum yields of photolysis of ONB-substituted terthiophenes, and (ii) the percentage of polymer that persists in UV-irradiated thin films upon rinsing with chloroform. These polymers behave as negative-tone photoresists, enabling both direct photopatterning of conjugated polymers, and fabrication of multilayer conjugated polymer films by irradiating with UV light after each spin-casting step. Although hole-mobility values of these polymers in thin film transistors were only ∼10 −5 cm 2 V −1 s −1 , photolysis and rinsing did not cause significant degradation in performance.

We show that p- and n-type light emitting field-effect transistors (LEFETs) can be made using “superyellow” as a light-emitting polymer, poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) as a p-type material and a naphthalene di-imide as an n-type material. By connecting two of these LEFETs, we have demonstrated a light emitting complementary inverter (LECI). The LECI exhibited electrical and optical characteristics in the first and third quadrant of the transfer characteristics with voltage gain of 6 and 8, respectively.

Compared to linear acenes, only a few examples of peri-condensed organic semiconductors are known. Here, we report synthesis and charge transport properties of peri-condensed heteropyrenes in organic field effect transistors (OFETs). We show that 1,6-dioxapyrene derivatives are easily accessible and stable semiconductors that form well-ordered polycrystalline films, which results in moderately large hole mobility (ca. 0.25 cm 2 V -1 s -1 ) in OFET devices.

Abstract. K9BiU6024 , M~ = 2373.06, cubic, Pm3m, a = 8.631 (1).~, V= 643.0 (2),~3, Z= 1, D,. = 6.128 g cm -3, ,t(Mo K~) = 0.7107/~,, /.1, = 440.5 cm-', F(000) = 998, T = 290 K, R = 0.047, wR = 0.052 for 192 reflections with I> 2o-(11. This new perovskite is closely related to K9U6022.5, with two different kinds of uranyl octahedra and regular octahedra of bismuth and potassium.