2,6-Diarylnaphtho[1,8-bc:5,4-b'c']dithiophenes as new high-performance semiconductors for organic field-effect transistors

A series of 2,6-diaryl-substituted naphtho[1,8-bc:5,4-b'c']dithiophene derivatives 2-6, whose aryl groups include 5-hexyl-2-thienyl, 2,2'-bithiophen-5-yl, phenyl, 2-naphthyl, and 4-biphenylyl, was synthesized by the palladium-catalyzed Suzuki-Miyaura coupling and utilized as active layers of organic field-effect transistors (OFETs). All devices fabricated using vapor-deposited thin films of these compounds showed typical p-type FET characteristics. The mobilities are relatively good and widely range from 10(-4) to 10(-1) cm2 V(-1) s(-1), depending on the substituent groups. Among them, the mobilities of the devices using films of 3-5 tend to increase with the increasing temperature of the Si/SiO2 substrate during film deposition. In particular, the device based on the naphthyl derivative 5, when fabricated at 140 degrees C, marked a high mobility of 0.11 cm2 V(-1) s(-1) with an on/off ratio of 10(5), which is a top class of performance among organic thin-film transistors. Studies of X-ray diffractograms (XRDs) have revealed that the film of 4 and 5 is composed of two kinds of crystal grains with different phases, so-called "single-crystal phase" and "thin film phase", and that the proportion of the thin film phase increases with an increase of the substrate temperature. In the thin film phase the assembled molecules stand nearly upright on the substrate in such a way as to be favorable to carrier migration.     

Organic semiconducting materials from sulfur-hetero benzo[k]fluoranthene derivatives: synthesis, photophysical properties, and thin film transistor fabrication

A new family of air-stable sulfur-hetero oligoarenes based on the benzo[k]fluoranthene unit has been facilely developed as the active materials for thin film organic field-effect transistors. The Diels-Alder reaction between cyclopentadienone 1 and 2,2'-(ethyne-1,2-diyl)bisthiophene followed by decarbonylation afforded fluoranthene derivative 2. After bromination and subsequent substitution through Suzuki coupling reaction, the FeCl3-oxidative cyclization produced sulfur-hetero benzo[k]fluoranthene derivatives 8-12. In dilute chloroform solution, the absorption and emission behaviors of 2 and 4-7 showed characteristic features of the fluoranthene units, while their emission lambda(max) red-shifted with an increase of the effective conjugation length. The steady state absorption and emission spectra of these newly synthesized compounds were thoroughly investigated and discussed. Thin film organic field-effect transistors (OFETs) using 8-11 as active materials were fabricated in a "top contact" configuration. Substituents at the skeleton play an important role in the film morphologies, which lead to different mobilities, while the charge mobilities of 8-11 from OFETs were improved after thermal annealing of the thin films. A carrier mobility as high as 0.083 cm(2) V(-1) s(-1) and current on/off ratio of 10(6) were achieved through vacuum-deposited film followed by the thermal annealing process from 11.     

Synthesis, properties, and OFET characteristics of 5,5'-di(2-azulenyl)-2,2'-bithiophene (DAzBT) and 2,5-di(2-azulenyl)-thieno[3,2-b]thiophene (DAzTT)

Two azulene-based π-conjugated systems, 5,5'-di(2-azulenyl)-2,2'-bithiophene and 2,5-di(2-azulenyl)-thieno[3,2-b]thiophene, were constructed via Suzuki-Miyaura cross-coupling reactions. The crystal structures of both revealed an edge-to-face orientation in a well-defined herringbone packing. The molecules stood nearly perpendicular to the substrate in the film form, with features of an organic field-effect transistor at hole mobilities of up to 5.0 × 10(-2) cm(2) V(-1) s(-1).     

Structural influences of organonitrogen ligands on vanadium oxide solids. Hydrothermal syntheses and structures of the terpyridine vanadates [V2O4(terpy)2]3[V10O28], [VO2(terpy)][V4O10], and [V9O22(terpy)3

Hydrothermal reactions of the V2O5/2,2':6':2"-terpyridine/ZnO/H2O system under a variety of conditions yielded the organic-inorganic hybrid materials [V2O4(terpy)2]3[V10O28].2H2O (VOXI-10), [VO2(terpy)][V4O10] (VOXI-11), and [V9O22(terpy)3] (VOXI-12). The structure of VOXI-10 consists of discrete binuclear cations [V2O4(terpy)2]2+ and one-dimensional chains [V10O28]6-, constructed of cyclic [V4O12]4- clusters linked through (VO4) tetrahedra. In contrast, the structure of VOXI-11 exhibits discrete mononuclear cations [VO2(terpy)]1+ and a two-dimensional vanadium oxide network, [V4O10]1-. The structure of the oxide layer is constructed from ribbons of edge-sharing square pyramids; adjacent ribbons are connected through corner-sharing interactions into the two-dimensional architecture. VOXI-12 is also a network structure; however, in this case the terpy ligand is incorporated into the two-dimensional oxide network whose unique structure is constructed from cyclic [V6O18]6- clusters and linear (V3O5(terpy)3) moieties of corner-sharing vanadium octahedra. The rings form chains through corner-sharing linkages; adjacent chains are connected through the trinuclear units. Crystal data: VOXI-10, C90H70N18O42V16, triclinic P1, a = 12.2071(7) A, b = 13.8855(8) A, 16.9832(10) A, alpha = 69.584(1) degrees, beta = 71.204(1) degrees, gamma = 84.640(1) degrees, Z = 1; VOXI-11, C15H11N3O12V5, monoclinic, P2(1)/n, a = 7.7771(1) A, b = 10.3595(2) A, c = 25.715(4) A, beta = 92.286(1) degrees, Z = 4; VOXI-12, C45H33N9O22V9, monoclinic C2/c, a = 23.774(2) A, b = 9.4309(6) A, c = 25.380(2) A, beta = 112.047(1) degrees, Z = 4.     

Benzo[1,2-b:4,5-b']bis[b]benzothiophene as solution processible organic semiconductor for field-effect transistors

Coplanar benzo[1,2-b:4,5-b']bis[b]benzothiophenes (, ) for the application in organic field-effect transistors were synthesized by a simple two-step procedure involving triflic acid induced ring-closure reaction; such solution processed devices show a hole mobility of up to 0.01 cm(2) V(-1) s(-1).     

General synthesis of dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) derivatives

A new straightforward synthesis of dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) derivatives from readily available 2-methoxynaphthalenes is described. Thus, newly developed derivatives of DNTT showed very high field effect mobility in the vapor-processed field-effect transistors up to 8 cm(2) V(-1) s(-1).     

Synthesis, characterization, and application of indolo[3,2-b]carbazole semiconductors

The synthesis, characterization, and field-effect transistor (FET) properties of new indolo[3,2-b]carbazoles are described. In particular, an extensive characterization of their crystal structures has revealed the importance of the nature of the side chains (alkyl, phenyl, thienyl substituents) on their solid-state organization. These organic materials have exhibited p-type FET behavior with hole mobilities as high as 0.2 cm2 V(-1) s(-1) with an on/off current ratio higher than 10(6). Best results were obtained with phenyl-substituted indolo[3,2-b]carbazoles since the presence of phenyl substituents seems to allow efficient overlap between the oligomeric molecules. More importantly, FET properties were kept constant during several months in air.     

Poly[3-(5-octyl-thienylene-vinyl)-thiophene]: a side-chain conjugated polymer with very broad absorption band

A novel polythiophene derivative, poly[3-(5-octyl-thienylene-vinyl)-thiophene] (POTVT) with conjugated thienylene vinyl side-chain, was synthesized, and the POTVT film shows a very broad absorption band-width covering from 300 nm to 700 nm after thermal annealing at 130 degrees C for 10 min.     

Activation volume measurement for C[bond]H activation. Evidence for associative benzene substitution at a platinum(II) center

The reaction of the platinum(II) methyl cation [(N-N)Pt(CH(3))(solv)](+) (N-N = ArN[double bond]C(Me)C(Me)[double bond]NAr, Ar = 2,6-(CH(3))(2)C(6)H(3), solv = H(2)O (1a) or TFE = CF(3)CH(2)OH (1b)) with benzene in TFE/H(2)O solutions cleanly affords the platinum(II) phenyl cation [(N-N)Pt(C(6)H(5))(solv)](+) (2). High-pressure kinetic studies were performed to resolve the mechanism for the entrance of benzene into the coordination sphere. The pressure dependence of the overall second-order rate constant for the reaction resulted in Delta V(++) = -(14.3 +/- 0.6) cm(3) mol(-1). Since the overall second order rate constant k = K(eq)k(2), Delta V(++) = Delta V degrees (K(eq)) + Delta V(++)(k(2)). The thermodynamic parameters for the equilibrium constant between 1a and 1b, K(eq) = [1b][H(2)O]/[1a][TFE] = 8.4 x 10(-4) at 25 degrees C, were found to be Delta H degrees = 13.6 +/- 0.5 kJ mol(-1), Delta S degrees = -10.4 +/- 1.4 J K(-1) mol(-1), and Delta V degrees = -4.8 +/- 0.7 cm(3) mol(-1). Thus DeltaV(++)(k(2)) for the activation of benzene by the TFE solvento complex equals -9.5 +/- 1.3 cm(3) mol(-1). This significantly negative activation volume, along with the negative activation entropy for the coordination of benzene, clearly supports the operation of an associative mechanism.     

High-performance field-effect transistors based on Langmuir-Blodgett films of cyclo[8]pyrrole

We demonstrate the field-effect transistors (FETs) made of cyclo[8]pyrrole thin films prepared by the Langmuir-Blodgett (LB) method. The cyclo[8]pyrrole molecule possesses a 30-pi-electron system and narrower highest-occupied molecular orbital-lowest-unoccupied molecular orbital energy gap (0.63 eV), forms a stable, reproducible monolayer at the air-water interface, and transfers onto a substrate with a nearly unity transfer ratio and face-to-face configuration due to its strong pi-pi interaction. The LB films are uniform characterized by atomic force microscopy and in ordered form confirmed by X-ray diffraction. The FET exhibited high performances with one of the highest hole mobilities (0.68 cm2 V(-1) s(-1)) for thin-film transistors and a high on/off ratio, implying a promising material in the FET family.     

Aceno[2,1,3]thiadiazoles for field-effect transistors: synthesis and crystal packing

An efficient synthetic approach to a series of aceno[2,1,3]thiadiazole derivatives is described. 2-TIPS and 2-TES molecules exhibited different crystal packings, and 2-TIPS show good device performances with hole mobility up to 0.4 cm(2) V(-1) s(-1) and an average mobility of 0.15 cm(2) V(-1) s(-1) as the active material for organic field-effect transistors. All of the results demonstrate these aceno[2,1,3]thiadiazole derivatives as promising materials for optoelectronic devices.     

Reactivity and structural and physical studies of tetranuclear iron(III) clusters containing the [Fe4(mu3-O)2]8+ "butterfly" core: an FeIII4 cluster with an S = 1 ground state

The initial use of di-2-pyridyl ketone oxime [(py)2CNOH] in iron(III) carboxylate chemistry has yielded the tetranuclear complex [Fe4O2Cl2(O2CMe)2{(py)2CNO}4] (1). Compound 1 can be synthesized either by the 1:2:1 molar ratio reaction between Fe(III), MeCO2-, and (py)2CNOH (complex 1a) or by the 1:3 molar ratio reaction between [Fe3O(O2CMe)6(H2O)3]Cl and (py)2CNOH (complex 1b). The presence of N3- in both reaction mixtures has afforded the tetranuclear complex [Fe4O2(N3)2(O2CMe)2{(py)2CNO}4] (2), which can be alternatively synthesized by the reaction of 1 with N3-. Compound 1a crystallizes in the tetragonal space group /-4 with (at 25 degrees C) a = 35.06(2) A, b = 35.06(2) A, c = 13.255(6) A, V = 16293(2) A(3), and Z = 8. Compound 1b crystallizes in the monoclinic space group P2(1)/c with (at 25 degrees C) a = 22.577(7) A, b = 17.078(6) A, c = 17.394(6) A, beta = 93.50(1) degrees , V = 6694(4) A(3), and Z = 4. Compound 2 crystallizes in the triclinic space group P1 with (at 25 degrees C) a = 13.658(9) A, b = 15.815(9) A, c = 17.29(1) A, alpha = 97.08(3) degrees , beta = 98.55(3) degrees , gamma = 112.12(3) degrees , V = 3355(4) A(3), and Z = 2. The structures of 1 and 2 contain the [Fe4(mu3-O)2]8+ core comprising four Fe(III) ions in a "butterfly" disposition and two mu3-O2- ions, each bridging three Fe(III) ions forming the "wings" of the "butterfly". The M?ssbauer spectra of 1b and 2 consist of composite quadrupole-split doublets, with parameters typical for high-spin Fe(III) in octahedral environments. Magnetic susceptibility measurements on 1a revealed antiferromagnetic interactions between the S = 5/2 ferric ions, with best-fit parameters being J(wb) = -40.2 cm(-1) and J(bb) = -59.4 cm(-1) (H = -2SigmaJiJj) for wingtip-body and body-body interactions, respectively, yielding an S = 1 ground state. Both wingtip-body and body-body interactions are well determined.     

Rational Design of Ambipolar Organic Semiconductors: Is Core Planarity Central to Ambipolarity in Thiophene–Naphthalene Semiconductors?

Herein, we report a new family of naphthaleneamidinemonoimide-fused oligothiophene semiconductors designed for facile charge transport in organic field-effect transistors (OFETs). These molecules have planar skeletons that induce high degrees of crystallinity and hence good charge-transport properties. By modulating the length of the oligothiophene fragment, the majority carrier charge transport can be switched from n-type to ambipolar behavior. The highest FET performance is achieved for solution-processed films of 10-[(2,2'-bithiophen)-5-yl]-2-octylbenzo[lmn]thieno[3',4':4,5]imidazo[2,1-b][3,8]phenanthroline-1,3,6(2H)-trione (NDI-3 Tp), with optimized film mobilities of 2×10(-2) and 0.7×10(-2) cm(2) V(-1) s(-1) for electrons and holes, respectively. Finally, these planar semiconductors are compared with their twisted-skeleton counterparts, which exhibit only n-type mobility, in order to understand the origin of the ambipolarity in this new series of molecular semiconductors.     

Oxo- and imidovanadium complexes incorporating methylene- and dimethyleneoxa-bridged calix[3]- and -[4]arenes: synthesis, structures and ethylene polymerisation catalysis

Reaction of [V(X)(OR)3] (X=O, Np-tolyl; R=Et, nPr or tBu) with p-tert-butylhexahomotrioxacalix[3]areneH3, LH3, affords the air-stable complexes [{V(X)L}n] (X=O, n=1 (1); X=Np-tolyl, n=2 (2)). Alternatively, 1 is readily available either from interaction of [V(mes)3THF] with LH3, and subsequent oxidation with O2 or upon reaction of LLi3 with [VOCl3]. Reaction of [V(Np-tolyl)(OtBu)3] with 1,3-dimethylether-p-tert-butylcalix[4]areneH2, Cax(OMe)2(OH)2, afforded [{VO(OtBu)}2(mu-O)Cax(OMe)2(O)2].2 MeCN (42 MeCN), in which two vanadium atoms are bound to just one calix[4]arene ligand; the n-propoxide analogue of 4, namely [{VO(OnPr)}2(mu-O)Cax(OMe)2(O)2].1.5 MeCN (51.5 MeCN), has also been isolated from a similar reaction using [V(O)(OnPr)3]. Reaction of [VOCl3], LiOtBu, (Me3Si)2O and Cax(OMe)2(OH)2 gave [{VO(OtBu)Cax(OMe)2(O)2}2Li4O2].8 MeCN (68 MeCN), in which an Li4O4 cube (two of the oxygen atoms are derived from the calixarene ligands) is sandwiched between two Cax(OMe)2(O)2. The reaction between [V(Np-tolyl)(OtBu)3] and Cax(OMe)2(OH)2, afforded [V(Np-tolyl)(OtBu)2Cax(OMe)2(O)(OH)]5 MeCN (75 MeCN), in which two tert-butoxide groups remain bound to the tetrahedral vanadium atom, which itself is bound to the calix[4]arene through only one phenolic oxygen atom. Reaction of p-tert-butylcalix[4]areneH4, Cax(OH)4 and [V(Np-tolyl)(OnPr)3] led to loss of the imido group and formation of the dimeric complex [{VCax(O)4(NCMe)}2].6 MeCN (86 MeCN). Monomeric vanadyl oxo- and imidocalix[4]arene complexes [V(X)Cax(O)3(OMe)(NCMe)] (X=O (11), Np-tolyl (12)) were obtained by the reaction of the methylether-p-tert-butylcalix[4]areneH3, Cax(OMe)(OH)3, and [V(X)(OR)3] (R=Et or nPr). Vanadyl calix[4]arene fragments can be linked by the reaction of 2,6-bis(bromomethyl)pyridine with Cax(OH)4 and subsequent treatment with [VOCl3] to afford the complex [{VOCax(O)4}2(mu-2,6-(CH2)2C5H3N)].4 MeCN (134 MeCN). The compounds 1-13 have been structurally characterised by single-crystal X-ray diffraction. Upon activation with methylaluminoxane, these complexes displayed poor activities, however, the use of dimethylaluminium chloride and the reactivator ethyltrichloroacetate generates highly active, thermally stable catalysts for the conversion of ethylene to, at 25 degrees C, ultra-high-molecular-weight (>5, 500,000), linear polyethylene, whilst at higher temperature (80 degrees C), the molecular weight of the polyethylene drops to about 450,000. Using 1 and 2 at 25 degrees C for ethylene/propylene co-polymerisation (50:50 feed) leads to ultra-high-molecular-weight (>2,900,000) polymer with about 14.5 mol% propylene incorporation. The catalytic systems employing the methyleneoxa-bridged complexes 1 and 2 are an order of magnitude more active than the bimetallic complexes 5 and 13, which, in turn, are an order of magnitude more active than pro-catalysts 8, 11 and 12. These differences in activity are discussed in terms of the structures of each class of complex.     

Synthesis and characteristics of a nonaggregating tris(tetrathiafulvaleno)dodecadehydro[18]annulene

A new tris(tetrathiafulvaleno)dodecadehydro[18]annulene with six peripheral n-hexyl substituents was prepared by oxidative Glaser-Hay cyclization of a corresponding diethynylated tetrathiafulvalene (TTF) precursor. The electronic properties of the neutral and oxidized species were studied by both UV/Vis absorption spectroscopy and electrochemistry. From these studies, it transpires that the strongly violet-colored macrocycle does not aggregate in solution to any significant degree, which was confirmed by (1)H NMR spectroscopy. This reluctance towards aggregation contrasts that observed for related TTF-annulenes containing other peripheral substitutents. Oxidation of the TTF-annulene occurs in two three-electron steps as inferred from both the peak amplitudes and the spectroelectrochemical study. We find that the tris(TTF)-fused dehydro[18]annulene is more difficult to oxidize (by +0.20 V) than the silyl-protected diethynylated mono-TTF precursor. In contrast, the first vertical ionization energy calculated at the B3 LYP/6-311+G(2d,p) level for the parent tris(TTF)-fused dehydro[18]annulene devoid of peripheral hexyl substituents is in fact lower (by 0.44 eV). Moreover, the surface morphology of 1 d drop-cast on a mica substrate was investigated by atomic force microscopy (AFM). Crystalline domains with slightly different orientations were observed. The thickness of individual layers seen in the crystalline domains and the thickness of a monolayer obtained from a very dilute solution were determined to 1.8-1.9 nm. This thickness corresponds to the diameter of the macrocycle and the layers seen in the film are apparently formed when the molecules stack in the horizontal direction relative to the substrate.     

杯[4]芳烃的表面化学组装及其在气态四氢呋喃荧光传感薄膜创制中的应用

挥发性有机化合物(Volatile Organic Compounds,VOCs)是重要的大气污染物,严重地危害着人类健康.本文设计合成了一种末端携带反应活性硅氧烷基团的杯[4]芳烃衍生物,通过自组装和表面化学反应将其共价结合于玻璃基质表面,获得了一种杯[4]芳烃修饰玻璃基质.以此基质物理担载荧光活性物质--芘封端三聚噻吩(Py-3T),得到了一种对气相四氢呋喃具有"turn-on"及快速灵敏(26.7 μg/mL)响应特性的荧光传感薄膜.实验表明:除苯和甲苯之外,其它常见有机溶剂和化学物质蒸汽对该薄膜荧光发射基本没有影响.苯和甲苯也因响应程度小、响应速度慢而难以干扰测定过程.据此,可以预期该荧光薄膜有可能在THF气体传感上获得应用.     

Trimerization of alkali dicyanamides M[N(CN)2] and formation of tricyanomelaminates M3[C6N9] (M = K, Rb) in the melt: crystal structure determination of three polymorphs of K[N(CN)2], two of Rb[N(CN)2], and one of K3[C6N9] and Rb3[C6N9] from X-ray powder diffractometry

The alkali dicyanamides M[N(CN)2] (M=K, Rb) were synthesized through ion exchange, and the corresponding tricyanomelaminates M3[C6N9] were obtained by heating the respective dicyanamides. The thermal behavior of the dicyanamides and their reaction to form the tricyanomelaminates were investigated by temperature-dependent X-ray powder diffractometry and thermoanalytical measurements. Potassium dicyanamide K[N(CN)2] was found to undergo four phase transitions: At 136 degrees C the low-temperature modification alpha-K[N(CN)2] transforms to beta-K[N(CN)2], and at 187degrees C the latter transforms to the high-temperature modification gamma-K[N(CN)2], which melts at 232 degrees C. Above 310 degrees C the dicyanamide ions [N(CN)2]- trimerize and the resulting tricyanomelaminate K3[C6N9] solidifies. Two modifications of rubidium dicyanamide have been identified: Even at -25 degrees C, the a form slowly transforms to beta-Rb[N(CN)2] within weeks. Rb[N(CN)2] has a melting point of 190 degrees C. Above 260 degrees C the dicyanamide ions [N(CN)2]- of the rubidium salt trimerize in the melt and the tricyanomelaminate Rb3[C6N9] solidifies. The crystal structures of all phases were determined by powder diffraction methods and were refined by the Rietveld method. alpha-K[N(CN)2] (Pbcm, a = 836.52(1), b = 46.90(1), c =7 21.27(1) pm, Z = 4), gamma-K[N(CN)2] (Pnma, a = 855.40(3), b = 387.80(1), 1252.73(4) pm, Z = 4), and Rb[N(CN)2] (C2/c, a = 1381.56(2), b = 1000.02(1), c = 1443.28(2) pm, 116.8963(6) degrees, Z = 16) represent new structure types. The crystal structure of beta-K[N(CN)2] (P2(1/n), a = -726.92(1), b 1596.34(2), c = 387.037(5) pm, 111.8782(6) degrees, Z = 4) is similar but not isotypic to the structure of alpha Na[N(CN)2]. alpha-Rb[N(CN)2] (Pbcm, a = 856.09(1), b = 661.711(7), c = 765.067(9) pm, Z = 4) is isotypic with alpha-K[N(CN)2]. The alkali dicyanamides contain the bent planar anion [N(CN)2]- of approximate symmetry C2, (average bond lengths: C-N(bridge) 133, C-N(term) 113 pm; average angles N-C-N 170 degrees, C-N-C 120 degrees). K3[C6N9] (P2(1/c), a = 373.82(1), b = 1192.48(5), c = 2500.4(1) pm, beta = 101.406(3) degrees, Z = 4) and Rb,[C6N9] (P2(1/c), a = 389.93(2), b = 1226.06(6), c = 2547.5(1) pm, 98.741(5) degrees, Z=4) are isotypic and they contain the planar cyclic anion [C6N9]3-. Although structurally related, Na3[C6N9] is not isotypic with the tricyanomelaminates M3[C6N9] (M = K, Rb).     

Gas-phase methylation of [60]fullerene

Direct methylation of [60]fullerene via a gas-phase reaction in a CH4/H2 atmosphere was performed using a modified hot filament chemical vapor deposition method. Pressures were varied from 10 to 60 mbar and the substrate was maintained at 690 degrees C. High-resolution matrix-assisted laser desorption ionization (MALDI) mass spectrometry analysis showed signals corresponding to C60H18-2n(H,CH3)n. Collision-induced dissociation experiments confirmed a maximum of 18 ligands possible to the [60]fullerene cage.     

Indolo[3,2-b]carbazole-based thin-film transistors with high mobility and stability

Proper functionalization of indolo[3,2-b]carbazole led to a new class of high-performance organic semiconductors suitable for organic thin-film transistor (OTFT) applications. While 5,11-diaryl-substituted indolo[3,2-b]carbazoles without long alkyl side chains provided amorphous thin films upon vacuum deposition, those with sufficiently long alkyl side chains such as 5,11-bis(4-octylphenyl)indolo[3,2-b]carbazole self-organized readily into highly crystalline layered structures under similar conditions. OTFTs using channel semiconductors of this nature exhibited excellent field-effect properties, with mobility up to 0.12 cm(2) V(-1) s(-1) and current on/off ratio to 10(7). As this class of organic semiconductors has relatively low HOMO levels and large band gaps, they also displayed good environmental stability even with prolonged exposure to amber light, an appealing characteristic for OTFT applications.