High Electron Mobility in [1]Benzothieno[3,2-<i>b</i>][1]benzothiophene-Based Field-Effect Transistors: Toward n-Type BTBTs

Usta, Hakan,Kim, Dojeon,Ozdemir, Resul,Zorlu, Yunus,Kim, Sanghyo,Ruiz Delgado, M. Carmen,Harbuzaru, Alexandra,Kim, Seonhyoung,Demirel, Gö,khan,Hong, Jongin,Ha, Young-Geun,Cho, Kilwon,Facchetti, American Chemical Society 2019 Chemistry of materials Vol.31 No.14

<P>The first example of an n-type [1]benzothieno[3,2-<I>b</I>][1]benzothiophene (BTBT)-based semiconductor, <B>D(Ph</B><SUB><B>F</B></SUB><B>CO)-BTBT</B>, has been realized via a two-step transition-metal-free process without using chromatographic purification. Physicochemical and optoelectronic characterizations of the new semiconductor were performed in detail, and the crystal structure was accessed. The new molecule exhibits a large optical band gap (∼2.9 eV) and highly stabilized (Δ<I>E</I><SUB>LUMO</SUB> = 1.54 eV)/π-delocalized lowest unoccupied molecular orbital (LUMO) mainly comprising the BTBT π-core and in-plane carbonyl units. The effect of out-of-plane twisted (64°) pentafluorophenyl groups on LUMO stabilization is found to be minimal. Polycrystalline <B>D(Ph</B><SUB><B>F</B></SUB><B>CO)-BTBT</B> thin films prepared by physical vapor deposition exhibited large grains (∼2-5 μm sizes) and “layer-by-layer” stacked edge-on oriented molecules with an in-plane herringbone packing (intermolecular distances ∼3.25-3.46 Å) to favor two-dimensional (2D) source-to-drain (S → D) charge transport. The corresponding TC/BG-OFET devices demonstrated high electron mobilities of up to ∼0.6 cm<SUP>2</SUP>/V·s and <I>I</I><SUB>on</SUB>/<I>I</I><SUB>off</SUB> ratios over 10<SUP>7</SUP>−10<SUP>8</SUP>. These results demonstrate that the large band gap BTBT π-core is a promising candidate for high-mobility n-type organic semiconductors and, combination of very large intrinsic charge transport capabilities and optical transparency, may open a new perspective for next-generation unconventional (opto)electronics.</P> [FIG OMISSION]</BR>

Anthracenedicarboximide-based semiconductors for air-stable, <i>n</i>-channel organic thin-film transistors: materials design, synthesis, and structural characterization

Usta, Hakan,Kim, Choongik,Wang, Zhiming,Lu, Shaofeng,Huang, Hui,Facchetti, Antonio,Marks, Tobin J. The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.10

<P>A family of six <I>n</I>-channel organic semiconductors (<B>1–6</B>) based on the <I>N</I>,<I>N</I>′-dialkyl-2,3:6,7-anthracenedicarboximide (ADI) core was synthesized and characterized. These new semiconductors are functionalized with <I>n</I>-octyl (-<I>n</I>-C<SUB>8</SUB>H<SUB>17</SUB>), 1<I>H</I>,1<I>H</I>-perfluorobutyl (-<I>n</I>-CH<SUB>2</SUB>C<SUB>3</SUB>F<SUB>7</SUB>), cyano (–CN), and bromo (–Br) substituents, which results in wide HOMO and LUMO energy variations (∼1 eV) but negligible optical absorbance (<I>λ</I><SUB>max</SUB> = 418–436 nm) in the visible region of the solar spectrum. Organic thin-film transistors (OTFTs) were fabricated <I>via</I> semiconductor vapor-deposition, and the resulting devices exhibit exclusively electron transport with good carrier mobilities (<I>μ</I><SUB>e</SUB>) of 10<SUP>−3</SUP> to 0.06 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>. Within this semiconductor family, cyano core-substitution plays a critical role in properly tuning the LUMO energy to enable good electron transport in ambient conditions while maintaining a low level of ambient doping (<I>i.e.</I>, low <I>I</I><SUB>off</SUB>). Core-cyanated ADIs <B>3</B> and <B>6</B> exhibit air-stable TFT device operation with electron mobilities up to 0.04 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> in air. Very high current on/off ratios of >10<SUP>7</SUP> are measured with positive threshold voltages (<I>V</I><SUB>th</SUB> = 5–15 V) and low off currents (<I>I</I><SUB>off</SUB> = 10<SUP>−9</SUP> to 10<SUP>−12</SUP> A). Single-crystal structures of <I>N</I>,<I>N</I>′-1<I>H</I>,1<I>H</I>-perfluorobutyl ADIs <B>5</B> and <B>6</B> exhibit slipped-stack cofacial crystal packing with close π–π stacking distances of ∼3.2 Å. Additionally, close intermolecular interactions between imide-carbonyl oxygen and anthracene core-hydrogen are identified, which lead to the assembly of highly planar lamellar layers. Analysis of the air-stability of <B>1–6</B> thin films suggests that air-stability is mainly controlled by the LUMO energetics, and an electrochemical threshold of <I>E</I><SUB>red1</SUB> = −0.3 to −0.4 V is estimated to stabilize <I>n</I>-channel transport in this family of materials.</P> <P>Graphic Abstract</P><P>A new family of six air-stable <I>n</I>-channel organic semiconductors based on the <I>N</I>,<I>N</I>′-dialkyl-2,3:6,7-anthracenedicarboximide core has been synthesized and fully characterized. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1jm14713g'> </P>

Enhanced mass transfer rate and solubility of methane via addition of alcohols for Methylosinus trichosporium OB3b fermentation

김광민,김유진,양정모,하경수,Hakan Usta,이진원,김충익 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.46 No.-

The effect of alcohol on methane–water volumetric mass transfer coefficient (kLa) and solubility ofmethane was investigated in this study. Various alcohols including methanol, ethanol, 1-propanol,butanol, and pentanol were added to aqueous solution and enhancement of both methane–water kLa(from 72 h 1 to 471 h 1) and solubility (from 21.72 mg/L to 30.41 mg/L) was observed, depending onalcohol type and concentration. Among all alcohols, 1-propanol exhibited largest enhancement viabubble coalescence inhibition effect. Enhanced methane–water kLa and methane solubility in aqueoussolution were employed for the fermentation of Methylosinus trichosporium OB3b, and cell growth rateand maximum optical density were increased by 700% and 730%, respectively, by addition of 1-propanol.

Naphthalene diimide-based polymeric semiconductors. Effect of chlorine incorporation and n-channel transistors operating in water

Ryu, Gi-Seong,Chen, Zhihua,Usta, Hakan,Noh, Yong-Young,Facchetti, Antonio Cambridge University Press (Materials Research Soc 2016 MRS Communications Vol.6 No.1

<▼1><B>Abstract</B><P/></▼1><▼2><P>We demonstrate here the design, synthesis and characterization of two new chlorinated polymers, P(NDI2HD-T2Cl2) and P(NDI2OD-T2Cl2) based on <I>N,N</I>′-difunctionalized naphthalene diimide (NDI) and 3,3′-dichloro-2,2′-bithiophene (T2Cl2) moieties. Our results indicate that organic thin-film transistors (OTFTs) based on these new chlorinated polymers exhibit electron mobilities approaching 0.1 cm<SUP>2</SUP>V<SUP>−1</SUP>s<SUP>−1</SUP> (<I>I</I>on:<I>I</I>off ~ 10<SUP>6</SUP>-10<SUP>7</SUP>), with far less ambipolarity due to their lower highest occupied molecular orbital energies, and they are more stable under deleterious high-humidity conditions (RH ~ 60%) and upon submersion in water, compared with those fabricated with the parent non-chlorinated polymers. In addition, OTFTs fabricated with the new chlorinated polymers exhibit excellent operational stabilities with <3% degradations upon bias-stress test.</P></▼2>

Triisopropylsilylethynyl-substituted indenofluorenes: carbonyl <i>versus</i> dicyanovinylene functionalization in one-dimensional molecular crystals and solution-processed n-channel OFETs

Ozdemir, Resul,Park, Sangyun,Deneme, İ,brahim,Park, Yonghan,Zorlu, Yunus,Alidagi, Husniye Ardic,Harmandar, Kevser,Kim, Choongik,Usta, Hakan The Royal Society of Chemistry 2018 Organic chemistry frontiers Vol.5 No.20

<P>The design and synthesis of novel electron-deficient and solution-processable polycyclic aromatic hydrocarbons offers great opportunities for the development of low-cost and large-area (opto)electronics. Although (trialkylsilyl)ethynyl (R3Si-CC-) has emerged as a very popular unit to solubilize organic semiconductors, it has been applied only to a limited class of materials that are mostly substituted on short molecular axes. Herein, two novel solution-processable indenofluorene-based semiconductors, TIPS-IFDK and TIPS-IFDM, bearing (triisopropylsilyl)ethynyl end units at 2,8-positions (<I>long molecular axis substitution</I>) were synthesized, and their single-crystal structures, optoelectronic properties, solution-sheared thin-film morphologies/microstructures, and n-channel field-effect responses were studied. In accordance with the DFT calculations, the HOMO/LUMO energies of the new compounds are found to be −5.77/−3.65 eV and −5.84/−4.18 eV for TIPS-IFDK and TIPS-IFDM, respectively, reflecting the high electron deficiency of the new π-backbones. Both semiconductors exhibit slightly S-shaped molecular frameworks with highly coplanar IFDK/IFDM π-cores, and they form slipped π-stacked one-dimensional (1-D) columnar motifs in the solid state. However, substantial differences in the degree of π-π interactions and stacking distances (4.04 Å <I>vs.</I> 3.47 Å) were observed between TIPS-IFDK and TIPS-IFDM as a result of carbonyl <I>vs.</I> dicyanovinylene functionalization, which results in a three orders of magnitude variation in the charge carrier mobility of the corresponding thin films. Top-contact/bottom-gate OFETs fabricated <I>via</I> solution-shearing TIPS-IFDM yielded one of the best performances in the (trialkylsilyl)ethynyl literature (<I>μ</I>e = 0.02 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, <I>I</I>on/<I>I</I>off = 10<SUP>7</SUP>-10<SUP>8</SUP>, and <I>V</I>T ∼ 2 V under ambient atmosphere) for a 1-D polycrystalline semiconductor microstructure. To the best of our knowledge, the molecules presented here are the first examples of n-type semiconductors substituted with (trialkylsilyl)ethynyl groups on their long molecular axes.</P>

Solution-Processable BODIPY-Based Small Molecules for Semiconducting Microfibers in Organic Thin-Film Transistors

Ozdemir, Mehmet,Choi, Donghee,Kwon, Guhyun,Zorlu, Yunus,Cosut, Bunyemin,Kim, Hyekyoung,Facchetti, Antonio,Kim, Choongik,Usta, Hakan American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.22

<P>Electron-deficient pi-conjugated small molecules can function as electron-transporting semiconductors in various optoelectronic applications. Despite their unique structural, optical, and electronic properties, the development of BODIPY-based organic semiconductors has lagged behind that of other pi-deficient units. Here, we report the design and synthesis of two novel solution-proccessable BODIPY-based small molecules (BDY-3T-BDY and BDY-4T-BDY) for organic thin-film transistors (OTFTs). The new semiconductors were fully characterized by H-1/C-13 NMR, mass spectrometry, cyclic voltammetry, UV-vis spectroscopy, photoluminescence, differential scanning calorimetry, and thermogravimetric analysis. The single-crystal X-ray diffraction (XRD) characterization of a key intermediate reveals crucial structural properties. Solution-sheared top-contact/bottom-gate OTFTs exhibited electron mobilities up to 0.01 cm(2)/V center dot s and current on/off ratios of >10(8). Film microstructural and morphological characterizations indicate the formation of relatively long (similar to 0.1 mm) and micrometer-sized (1-2 mu m) crystalline fibers for BDY-4T-BDY-based films along the shearing direction. Fiber-alignment-induced charge-transport anisotropy (mu?/mu approximate to 10) was observed, and higher mobilities were achieved when the microfibers were aligned along the conduction channel, which allows for efficient long-range charge-transport between source and drain electrodes. These OTFT performances are the highest reported to date for a BODIPY-based molecular semiconductor, and demonstrate that BODIPY is a promising building block for enabling solution-processed, electron-transporting semiconductor films.</P>

Ultralow bandgap molecular semiconductors for ambient-stable and solution-processable ambipolar organic field-effect transistors and inverters

Ozdemir, Resul,Choi, Donghee,Ozdemir, Mehmet,Kwon, Guhyun,Kim, Hyekyoung,Sen, Unal,Kim, Choongik,Usta, Hakan The Royal Society of Chemistry 2017 Journal of Materials Chemistry C Vol.5 No.9

<P>The design and development of novel ambipolar semiconductors is very crucial to advance various optoelectronic technologies including organic complementary (CMOS) integrated circuits. Although numerous high-performance ambipolar polymers have been realized to date, small molecules have been unable to provide high ambipolar performance in combination with ambient-stability and solution-processibility. In this study, by implementing highly π-electron deficient, ladder-typeIFDK/IFDMacceptor cores with bithiophene donor units in D-A-D π-architectures, two novel small molecules,2OD-TTIFDKand2OD-TTIFDM, were designed, synthesized and characterized in order to achieve ultralow band-gap (1.21-1.65 eV) semiconductors with sufficiently balanced molecular energetics for ambipolarity. The HOMO/LUMO energies of the new semiconductors are found to be −5.47/−3.61 and −5.49/−4.23 eV, respectively. Bottom-gate/top-contact OFETs fabricated<I>via</I>solution-shearing of2OD-TTIFDMyield perfectly ambient stable ambipolar devices with reasonably balanced electron and hole mobilities of 0.13 cm<SUP>2</SUP>V<SUP>−1</SUP>s<SUP>−1</SUP>and 0.01 cm<SUP>2</SUP>V<SUP>−1</SUP>s<SUP>−1</SUP>, respectively with<I>I</I>on/<I>I</I>offratios of ∼10<SUP>3</SUP>-10<SUP>4</SUP>, and2OD-TTIFDK-based OFETs exhibit ambipolarity under vacuum with highly balanced (<I>μ</I>e/<I>μ</I>h∼ 2) electron and hole mobilities of 0.02 cm<SUP>2</SUP>V<SUP>−1</SUP>s<SUP>−1</SUP>and 0.01 cm<SUP>2</SUP>V<SUP>−1</SUP>s<SUP>−1</SUP>, respectively with<I>I</I>on/<I>I</I>offratios of ∼10<SUP>5</SUP>-10<SUP>6</SUP>. Furthermore, complementary-like inverter circuits were demonstrated with the current ambipolar semiconductors resulting in high voltage gains of up to 80. Our findings clearly indicate that ambient-stability of ambipolar semiconductors is a function of molecular orbital energetics without being directly related to a bulk π-backbone structure. To the best of our knowledge, considering the processing, charge-transport and inverter characteristics, the current semiconductors stand out among the best performing ambipolar small molecules in the OFET and CMOS-like circuit literature. Our results provide an efficient approach in designing ultralow band-gap ambipolar small molecules with good solution-processibility and ambient-stability for various optoelectronic technologies, including CMOS-like integrated circuits.</P>