370 results found
Fei Z, Eisner FD, Jiao X, et al., 2018, Correction: An alkylated indacenodithieno[3,2-b] thiophene-based nonfullerene acceptor with high crystallinity exhibiting single junction solar cell efficiencies greater than 13% with low voltage losses (vol 30, 2018), Advanced Materials, Vol: 30, ISSN: 0935-9648
Huang W, Lin Y-H, Anthopoulos TD, 2018, High Speed Ultraviolet Phototransistors Based on an Ambipolar Fullerene Derivative, ACS APPLIED MATERIALS & INTERFACES, Vol: 10, Pages: 10202-10210, ISSN: 1944-8244
Lu R, Han Y, Zhang W, et al., 2018, Alkylated indacenodithieno[3,2-b] thiophene-based all donor ladder-type conjugated polymers for organic thin film transistors, Journal of Materials Chemistry C, Vol: 6, Pages: 2004-2009, ISSN: 2050-7534
We report the synthesis of a series of indacenodithieno[3,2-b]thiophene (IDTT) based conjugated polymers by copolymerization with three different electron rich co-monomers [thiophene (T), thieno[3,2-b] thiophene (TT) and dithieno[3,2-b:2′,3′-d]thiophene (DTT)] under Stille coupling conditions. The resulting all-donor polymers show very good solubility in common solvents and exhibit similar optical, thermal and electronic properties. However, the performance of these semiconductors in thin film transistor devices varied and was highly dependent on the nature of the co-monomer. All polymers exhibited unipolar p-type charge transport behaviour, with the mobility values following the trend of IDTT-TT > IDTT-DTT > IDTT-T. The peak saturation mobility value of IDTT-TT was extracted to be 1.1 cm 2 V -1 s -1 , amongst the highest mobility for all-donor conjugated polymers reported to date.
Fei Z, Eisner FD, Jiao X, et al., 2018, An alkylated indacenodithieno[3,2-b]thiophene-based nonfullerene acceptor with high crystallinity exhibiting single junction solar cell efficiencies greater than 13% with low voltage losses, Advanced Materials, Vol: 30, ISSN: 0935-9648
A new synthetic route, to prepare an alkylated indacenodithieno[3,2-b]thiophene-based nonfullerene acceptor (C8-ITIC), is reported. Compared to the reported ITIC with phenylalkyl side chains, the new acceptor C8-ITIC exhibits a reduction in the optical band gap, higher absorptivity, and an increased propensity to crystallize. Accordingly, blends with the donor polymer PBDB-T exhibit a power conversion efficiency (PCE) up to 12.4%. Further improvements in efficiency are found upon backbone fluorination of the donor polymer to afford the novel material PFBDB-T. The resulting blend with C8-ITIC shows an impressive PCE up to 13.2% as a result of the higher open-circuit voltage. Electroluminescence studies demonstrate that backbone fluorination reduces the energy loss of the blends, with PFBDB-T/C8-ITIC-based cells exhibiting a small energy loss of 0.6 eV combined with a high JSCof 19.6 mA cm-2.
Lin Y-H, Pattanasattayavong P, Anthopoulos TD, 2017, Metal-Halide Perovskite Transistors for Printed Electronics: Challenges and Opportunities, ADVANCED MATERIALS, Vol: 29, ISSN: 0935-9648
Wyatt-Moon G, Georgiadou DG, Semple J, et al., 2017, Deep Ultraviolet Copper(I) Thiocyanate (CuSCN) Photodetectors Based on Coplanar Nanogap Electrodes Fabricated via Adhesion Lithography., ACS Applied Materials and Interfaces, Vol: 9, Pages: 41965-41972, ISSN: 1944-8244
Adhesion lithography (a-Lith) is a versatile fabrication technique used to produce asymmetric coplanar electrodes separated by a <15 nm nanogap. Here, we use a-Lith to fabricate deep ultraviolet (DUV) photodetectors by combining coplanar asymmetric nanogap electrode architectures (Au/Al) with solution-processable wide-band-gap (3.5-3.9 eV) p-type semiconductor copper(I) thiocyanate (CuSCN). Because of the device's unique architecture, the detectors exhibit high responsivity (≈79 A W-1) and photosensitivity (≈720) when illuminated with a DUV-range (λpeak = 280 nm) light-emitting diode at 220 μW cm-2. Interestingly, the photosensitivity of the photodetectors remains fairly high (≈7) even at illuminating intensities down to 0.2 μW cm-2. The scalability of the a-Lith process combined with the unique properties of CuSCN paves the way to new forms of inexpensive, yet high-performance, photodetectors that can be manufactured on arbitrary substrate materials including plastic.
Fallon KJ, Santala A, Wijeyasinghe N, et al., 2017, Effect of Alkyl Chain Branching Point on 3D Crystallinity in High N-Type Mobility Indolonaphthyridine Polymers, ADVANCED FUNCTIONAL MATERIALS, Vol: 27, ISSN: 1616-301X
The low reactive oxygen species production capability and the shallow tissue penetration of excited light (UV) are still two barriers in photodynamic therapy (PDT). Here, Au cluster anchored black anatase TiO2−x nanotubes (abbreviated as Au25/B-TiO2−x NTs) are synthesized by gaseous reduction of anatase TiO2 NTs and subsequent deposition of noble metal. The Au25/B-TiO2−x NTs with thickness of about 2 nm exhibit excellent PDT performance. The reduction process increased the density of Ti3+ on the surface of TiO2, which effectively depresses the recombination of electron and hole. Furthermore, after modification of Au25 nanoclusters, the PDT efficiency is further enhanced owing to the changed electrical distribution in the composite, which forms a shallow potential well on the metal–TiO2 interface to further hamper the recombination of electron and hole. Especially, the reduction of anatase TiO2 can expend the light response range (UV) of TiO2 to the visible and even near infrared (NIR) light region with high tissue penetration depth. When excited by NIR light, the nanoplatform shows markedly improved therapeutic efficacy attributed to the photocatalytic synergistic effect, and promotes separation or restrained recombination of electron and hole, which is verified by experimental results in vitro and in vivo.
Tetzner K, Lin Y-H, Regoutz A, et al., 2017, Sub-second photonic processing of solution-deposited single layer and heterojunction metal oxide thin-film transistors using a high-power xenon flash lamp, Journal of Materials Chemistry C, Vol: 5, Pages: 11724-11732, ISSN: 2050-7526
We report the fabrication of solution-processed In2O3 and In2O3/ZnO heterojunction thin-film transistors (TFTs) where the precursor materials were converted to their semiconducting state using high power light pulses generated by a xenon flash lamp. In2O3 TFTs prepared on glass substrates exhibited low-voltage operation (≤2 V) and a high electron mobility of ∼6 cm2 V−1 s−1. By replacing the In2O3 layer with a photonically processed In2O3/ZnO heterojunction, we were able to increase the electron mobility to 36 cm2 V−1 s−1, while maintaining the low-voltage operation. Although the level of performance achieved in these devices is comparable to control TFTs fabricated via thermal annealing at 250 °C for 1 h, the photonic treatment approach adopted here is extremely rapid with a processing time of less than 18 s per layer. With the aid of a numerical model we were able to analyse the temperature profile within the metal oxide layer(s) upon flashing revealing a remarkable increase of the layer's surface temperature to ∼1000 °C within ∼1 ms. Despite this, the backside of the glass substrate remains unchanged and close to room temperature. Our results highlight the applicability of the method for the facile manufacturing of high performance metal oxide transistors on inexpensive large-area substrates.
Semple J, Georgiadou DG, Wyatt-Moon G, et al., 2017, Flexible diodes for radio frequency (RF) electronics: a materials perspective, Semiconductor Science and Technology, Vol: 32, ISSN: 0268-1242
Over the last decade, there has been increasing interest in transferring the research advances in radiofrequency (RF) rectifiers, the quintessential element of the chip in the RF identification (RFID) tags, obtained on rigid substrates onto plastic (flexible) substrates. The growing demand for flexible RFID tags, wireless communications applications and wireless energy harvesting systems that can be produced at a low-cost is a key driver for this technology push. In this topical review, we summarise recent progress and status of flexible RF diodes and rectifying circuits, with specific focus on materials and device processing aspects. To this end, different families of materials (e.g. flexible silicon, metal oxides, organic and carbon nanomaterials), manufacturing processes (e.g. vacuum and solution processing) and device architectures (diodes and transistors) are compared. Although emphasis is placed on performance, functionality, mechanical flexibility and operating stability, the various bottlenecks associated with each technology are also addressed. Finally, we present our outlook on the commercialisation potential and on the positioning of each material class in the RF electronics landscape based on the findings summarised herein. It is beyond doubt that the field of flexible high and ultra-high frequency rectifiers and electronics as a whole will continue to be an active area of research over the coming years.
Panidi J, Paterson AF, Khim D, et al., 2017, Remarkable Enhancement of the Hole Mobility in Several Organic Small-Molecules, Polymers, and Small-Molecule:Polymer Blend Transistors by Simple Admixing of the Lewis Acid p-Dopant B(C6F5)(3), Advanced Science, Vol: 5, ISSN: 2198-3844
Improving the charge carrier mobility of solution-processable organic semiconductors is critical for the development of advanced organic thin-film transistors and their application in the emerging sector of printed electronics. Here, a simple method is reported for enhancing the hole mobility in a wide range of organic semiconductors, including small-molecules, polymers, and small-molecule:polymer blends, with the latter systems exhibiting the highest mobility. The method is simple and relies on admixing of the molecular Lewis acid B(C6F5)3 in the semiconductor formulation prior to solution deposition. Two prototypical semiconductors where B(C6F5)3 is shown to have a remarkable impact are the blends of 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene:poly(triarylamine) (diF-TESADT:PTAA) and 2,7-dioctyl-benzothieno[3,2-b]benzothiophene:poly(indacenodithiophene-co-benzothiadiazole) (C8-BTBT:C16-IDTBT), for which hole mobilities of 8 and 11 cm2 V−1 s−1, respectively, are obtained. Doping of the 6,13-bis(triisopropylsilylethynyl)pentacene:PTAA blend with B(C6F5)3 is also shown to increase the maximum hole mobility to 3.7 cm2 V−1 s−1. Analysis of the single and multicomponent materials reveals that B(C6F5)3 plays a dual role, first acting as an efficient p-dopant, and secondly as a microstructure modifier. Semiconductors that undergo simultaneous p-doping and dopant-induced long-range crystallization are found to consistently outperform transistors based on the pristine materials. Our work underscores Lewis acid doping as a generic strategy towards high performance printed organic microelectronics.
Pattanasattayavong P, Promarak V, Anthopoulos TD, 2017, Electronic Properties of Copper(I) Thiocyanate (CuSCN) (vol 3, 1600378, 2017), Advanced Electronic Materials, Vol: 3, ISSN: 2199-160X
Wijeyasinghe N, Regoutz A, Eisner F, et al., 2017, Copper(I) Thiocyanate (CuSCN) Hole-Transport Layers Processed from Aqueous Precursor Solutions and Their Application in Thin-Film Transistors and Highly Efficient Organic and Organometal Halide Perovskite Solar Cells, ADVANCED FUNCTIONAL MATERIALS, Vol: 27, ISSN: 1616-301X
This study reports the development of copper(I) thiocyanate (CuSCN) hole-transport layers (HTLs) processed from aqueous ammonia as a novel alternative to conventional n-alkyl sulfide solvents. Wide bandgap (3.4–3.9 eV) and ultrathin (3–5 nm) layers of CuSCN are formed when the aqueous CuSCN–ammine complex solution is spin-cast in air and annealed at 100 °C. X-ray photoelectron spectroscopy confirms the high compositional purity of the formed CuSCN layers, while the high-resolution valence band spectra agree with first-principles calculations. Study of the hole-transport properties using field-effect transistor measurements reveals that the aqueous-processed CuSCN layers exhibit a fivefold higher hole mobility than films processed from diethyl sulfide solutions with the maximum values approaching 0.1 cm2 V−1 s−1. A further interesting characteristic is the low surface roughness of the resulting CuSCN layers, which in the case of solar cells helps to planarize the indium tin oxide anode. Organic bulk heterojunction and planar organometal halide perovskite solar cells based on aqueous-processed CuSCN HTLs yield power conversion efficiency of 10.7% and 17.5%, respectively. Importantly, aqueous-processed CuSCN-based cells consistently outperform devices based on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate HTLs. This is the first report on CuSCN films and devices processed via an aqueous-based synthetic route that is compatible with high-throughput manufacturing and paves the way for further developments.
Isakov I, Faber H, Grell M, et al., 2017, Exploring the Leidenfrost Effect for the Deposition of High-Quality In2O3 Layers via Spray Pyrolysis at Low Temperatures and Their Application in High Electron Mobility Transistors, ADVANCED FUNCTIONAL MATERIALS, Vol: 27, ISSN: 1616-301X
Fei Z, Chen L, Han Y, et al., 2017, Alternating 5,5-Dimethylcyclopentadiene and Diketopyrrolopyrrole Copolymer Prepared at Room Temperature for High Performance Organic Thin-Film Transistors, Journal of the American Chemical Society, Vol: 139, Pages: 8094-8097, ISSN: 1520-5126
We report that the inclusion of nonaromatic 5,5-dimethylcyclopentadiene monomer into a conjugated backbone is an attractive strategy to high performance semiconducting polymers. The use of this monomer enables a room temperature Suzuki copolymerization with a diketopyrrolopyrrole comonomer to afford a highly soluble, high molecular weight material. The resulting low band gap polymer exhibits excellent photo and thermal stability, and despite a large π–π stacking distance of 4.26 Å, it demonstrates excellent performance in thin-film transistor devices.
Fei Z, Han Y, Gann E, et al., 2017, Alkylated selenophene-based ladder-type monomers via a facileroute for high performance thin-film transistor applications, Journal of the American Chemical Society, Vol: 139, Pages: 8552-8561, ISSN: 1943-2984
We report the synthesis of two new selenophene-containing ladder-type monomers, cyclopentadiselenophene (CPDS) and indacenodiselenophene (IDSe), via a 2-fold and 4-fold Pd-catalyzed coupling with a 1,1-diborylmethane derivative. Copolymers with benzothiadiazole were prepared in high yield by Suzuki polymerization to afford materials which exhibited excellent solubility in a range of nonchlorinated solvents. The CPDS copolymer exhibited a band gap of just 1.18 eV, which is among the lowest reported for donor–acceptor polymers. Thin-film transistors were fabricated using environmentally benign, nonchlorinated solvents, with the CPDS and IDSe copolymers exhibiting hole mobility up to 0.15 and 6.4 cm2 V–1 s–1, respectively. This high performance was achieved without the undesirable peak in mobility often observed at low gate voltages due to parasitic contact resistance.
Faber H, Das S, Lin Y-H, et al., 2017, Heterojunction oxide thin-film transistors with unprecedented electron mobility grown from solution., Science Advances, Vol: 3, ISSN: 2375-2548
Thin-film transistors made of solution-processed metal oxide semiconductors hold great promise for application in the emerging sector of large-area electronics. However, further advancement of the technology is hindered by limitations associated with the extrinsic electron transport properties of the often defect-prone oxides. We overcome this limitation by replacing the single-layer semiconductor channel with a low-dimensional, solution-grown In2O3/ZnO heterojunction. We find that In2O3/ZnO transistors exhibit band-like electron transport, with mobility values significantly higher than single-layer In2O3 and ZnO devices by a factor of 2 to 100. This marked improvement is shown to originate from the presence of free electrons confined on the plane of the atomically sharp heterointerface induced by the large conduction band offset between In2O3 and ZnO. Our finding underscores engineering of solution-grown metal oxide heterointerfaces as an alternative strategy to thin-film transistor development and has the potential for widespread technological applications.
Petti L, Pattanasattayavong P, Lin Y-H, et al., 2017, Solution-processed p-type copper(I) thiocyanate (CuSCN) for low-voltage flexible thin-film transistors and integrated inverter circuits, APPLIED PHYSICS LETTERS, Vol: 110, ISSN: 0003-6951
Khim D, Lin Y-H, Nam S, et al., 2017, Modulation-Doped In2O3/ZnO Heterojunction Transistors Processed from Solution, Advanced Materials, Vol: 29, ISSN: 0935-9648
This paper reports the controlled growth of atomically sharp In2O3/ZnO and In2O3/Li-doped ZnO (In2O3/Li-ZnO) heterojunctions via spin-coating at 200 °C and assesses their application in n-channel thin-film transistors (TFTs). It is shown that addition of Li in ZnO leads to n-type doping and allows for the accurate tuning of its Fermi energy. In the case of In2O3/ZnO heterojunctions, presence of the n-doped ZnO layer results in an increased amount of electrons being transferred from its conduction band minimum to that of In2O3 over the interface, in a process similar to modulation doping. Electrical characterization reveals the profound impact of the presence of the n-doped ZnO layer on the charge transport properties of the isotype In2O3/Li-ZnO heterojunctions as well as on the operating characteristics of the resulting TFTs. By judicious optimization of the In2O3/Li-ZnO interface microstructure, and Li concentration, significant enhancement in both the electron mobility and TFT bias stability is demonstrated.
Casey A, Green JP, Shakya Tuladhar P, et al., 2017, Cyano substituted benzotriazole based polymers for use in organic solar cells, Journal of Materials Chemistry A, Vol: 5, Pages: 6465-6470, ISSN: 2050-7496
A new synthetic route to the electron accepting di-cyano substituted benzo[d][1,2,3]triazole (BTz) monomer 2-(2-butyloctyl)-4,7-di(thiophen-2-yl)-2H-benzotriazole-5,6-dicarbonitrile (dTdCNBTz) is reported. The cyano substituents can be easily introduced to the BTz unit in one step via the nucleophilic aromatic substitution of the fluorine substituents of the fluorinated precursor 2-(2-butyloctyl)-4,7-di(thiophen-2-yl)-2H-benzotriazole-5,6-difluoro (dTdFBTz). Co-polymers were prepared with distannylated benzo[1,2-b:4,5-b′]dithiophene (BDT) monomers containing either 2-ethylhexylthienyl (T-EH) side chains or 2-butyloctylthienyl (T-BO) side chains via Stille coupling to yield the novel medium band gap polymers P1 and P2 respectively. Whilst the organic photovoltaic (OPV) performance of P1 was limited by a lack of solubility, the improved solubility of P2 resulted in promising device efficiencies of up to 6.9% in blends with PC61BM, with high open circuit voltages of 0.95 V.
Pattanasattayavong P, Promarak V, Anthopoulos TD, 2017, Electronic Properties of Copper(I) Thiocyanate (CuSCN), Advanced Electronic Materials, Vol: 3, ISSN: 2199-160X
With the emerging applications of copper(I) thiocyanate (CuSCN) as a transparent and solution-processable hole-transporting semiconductor in numerous opto/electronic devices, fundamental studies that cast light on the charge transport physics are essential as they provide insights critical for further materials and devices performance advancement. The aim of this article is to provide a comprehensive and up-to-date report of the electronic properties of CuSCN with key emphasis on the structure–property relationship. The article is divided into four parts. In the first section, recent works on density functional theory calculations of the electronic band structure of hexagonal β-CuSCN are reviewed. Following this, various defects that may contribute to the conductivity of CuSCN are discussed, and newly predicted phases characterized by layered 2-dimensional-like structures are highlighted. Finally, a summary of recent studies on the band-tail states and hole transport mechanisms in solution-deposited, polycrystalline CuSCN layers is presented.
Semple J, Wyatt-Moon G, Georgiadou DG, et al., 2017, Semiconductor-Free Nonvolatile Resistive Switching Memory Devices Based on Metal Nanogaps Fabricated on Flexible Substrates via Adhesion Lithography, IEEE TRANSACTIONS ON ELECTRON DEVICES, Vol: 64, Pages: 1973-1980, ISSN: 0018-9383
Dellis S, Isakov I, Kalfagiannis N, et al., Rapid laser-induced photochemical conversion of sol-gel precursors to In2O3 layers and their application in thin-film transistors, Journal of Materials Chemistry C, ISSN: 2050-7534
We report the development of indium oxide (In2O3) transistors via a singlestep laser-induced photochemical conversion process of a sol-gel metal oxideprecursor. Through careful optimization of the laser annealing conditions wedemonstrated successful conversion of the precursor to In2O3 and its subsequentimplementation in n-channel transistors with electron mobility up to 13 cm2/Vs.Importantly, the process does not require thermal annealing making itcompatible with temperature sensitive materials such as plastic. On the otherhand, the spatial conversion/densification of the sol-gel layer eliminatesadditional process steps associated with semiconductor patterning and hencesignificantly reduces fabrication complexity and cost. Our work demonstratesunambiguously that laser-induced photochemical conversion of sol-gel metaloxide precursors can be rapid and compatible with large-area electronicsmanufacturing.
Isakov I, Paterson AF, Solomeshch O, et al., 2016, Hybrid complementary circuits based on p-channel organic and n-channel metal oxide transistors with balanced carrier mobilities of up to 10 cm(2)/Vs, Applied Physics Letters, Vol: 109, ISSN: 1077-3118
We report the development of hybrid complementary inverters based on p-channel organic andn-channel metal oxide thin-film transistors (TFTs) both processed from solution at <200 C. For theorganic TFTs, a ternary blend consisting of the small-molecule 2,7-dioctylbenzothieno[3,2-b]benzothiophene, the polymer indacenodithiophene-benzothiadiazole (C16IDT-BT) and the p-typedopant C60F48 was employed, whereas the isotype In2O3/ZnO heterojunction was used for the nchannelTFTs. When integrated on the same substrate, p- and n-channel devices exhibited balancedcarrier mobilities up to 10 cm2/Vs. Hybrid complementary inverters based on these devices show highsignal gain (>30 V/V) and wide noise margins (70%). The moderate processing temperaturesemployed and the achieved level of device performance highlight the tremendous potential of the technologyfor application in the emerging sector of large-area microelectronics.
Tetzner K, Isakov I, Regoutz A, et al., 2016, The impact of post-deposition annealing on the performance of solution-processed single layer In2O3 and isotype In2O3/ZnO heterojunction transistors, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 5, Pages: 59-64, ISSN: 2050-7526
Nam S, Han H, Seo J, et al., 2016, Ambipolar Organic Phototransistors with p-Type/n-Type Conjugated Polymer Bulk Heterojunction Light-Sensing Layers, ADVANCED ELECTRONIC MATERIALS, Vol: 2, ISSN: 2199-160X
Fallon KJ, Wijeyasinghe N, Manley EF, et al., 2016, Indolo-naphthyridine-6,13-dione Thiophene Building Block for Conjugated Polymer Electronics: Molecular Origin of Ultrahigh n-Type Mobility, CHEMISTRY OF MATERIALS, Vol: 28, Pages: 8366-8378, ISSN: 0897-4756
Nam S, Seo J, Han H, et al., 2016, > 10% Efficiency Polymer: Fullerene Solar Cells with Polyacetylene-Based Polyelectrolyte Interlayers, ADVANCED MATERIALS INTERFACES, Vol: 3, ISSN: 2196-7350
Casey A, Han Y, Gann E, et al., 2016, Vinylene-linked oligothiophene–difluorobenzothiadiazole copolymer for transistor applications, ACS Applied Materials & Interfaces, Vol: 8, Pages: 31154-31165, ISSN: 1944-8244
The synthesis of the novel donor-acceptor monomer 4,7-bis[(E)-2-(5-bromo-3-dodecylylthiophen-2-yl)ethenyl]-5,6-difluoro-2,1,3-benzothiadiazole (FBT-V2T2) is reported. Polymerization with 4,4'-ditetradecyl-5,5'-bistrimethylstannyl-2,2'-bithiophene afforded a highly crystalline polymer that aggregated strongly in solution. Polymer films were well ordered resulting in high performance field-effect transistors with low onset voltages, negligible hysteresis, high channel current on/off ratios and peak hole mobilities of up to 0.5 cm2V-1s-1. Notably the transistors exhibited close to ideal behavior with extracted mobilities almost independent of gate of voltage.
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