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Ruofei Jia Xiaofeng Wu Wei Deng Xiujuan Zhang Liming Huang Kaifeng Niu Lifeng Chi Jiansheng Jie 《Advanced functional materials》2019,29(45)
Persistent photoconductivity (PPC) in organic phototransistors provides an opportunity and broad prospects to achieve many emerging applications in optoelectronic devices. However, a fundamental understanding of PPC behavior is still a key challenge impeding its practical applications. In this study, for the first time, a mechanism for electron trapping is presented in oxygen‐induced deep levels in organic semiconductors for the clarification of PPC behavior with solid evidence. Both theoretical simulation and experimental investigation unveil that oxygen in air atmosphere plays a decisive role in determining the PPC behavior. Oxygen molecules can induce deep defect levels in the energy bandgap of organic semiconductors, which will act as deep traps for photogenerated electrons. The trapped electrons will be maintained in the traps and undergo a very slow releasing process after light illumination, thus leading to a noticeable PPC behavior for the organic phototransistors. The proposed mechanism shows good universality and can be applicable to a host of organic semiconductors for explaining the PPC behaviors. This work reveals the significant role of oxygen in PPC behavior and also provides guidelines for controlling the unique PPC behavior toward device applications. 相似文献
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Chuan Qian Jia Sun Ling‐An Kong Guangyang Gou Menglong Zhu Yongbo Yuan Han Huang Yongli Gao Junliang Yang 《Advanced functional materials》2017,27(6)
High‐performance organic heterojunction phototransistors are fabricated using highly ordered copper phthalocyanine (CuPc) and para ‐sexiphenyl (p ‐6P) thin films. The p ‐6P thin film plays an important role on the performance of CuPc/p ‐6P heterojunction phototransistors. It acts as a molecular template layer to induce the growth of highly ordered CuPc thin film, which dramatically improves the charge transport and decreases the grain boundaries. On the other hand, the p ‐6P thin film can form an effective heterojunction with CuPc thin film, which is greatly helpful to enhance the light absorption and photogenerated carriers. Under 365 nm ultraviolet light irradiation, the ratio of photocurrent and dark current and photoresponsivity of CuPc/p ‐6P heterojunction phototransistors reaches to about 2.2 × 104 and 4.3 × 102 A W?1, respectively, which are much larger than that of CuPc phototransistors of about 2.7 × 102 and 7.3 A W?1, respectively. A detailed study carried out with current sensing atomic force microscopy proves that the photocurrent is predominately produced inside the highly ordered CuPc/p ‐6P heterojunction grains, while the photocurrent produced at the boundaries between grains can be neglected. The research provides a good method for fabricating high‐performance organic phototransistors using a combination of molecular template growth and organic heterojunction. 相似文献
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Katelyn P. Goetz Jun'ya Tsutsumi Sujitra Pookpanratana Jihua Chen Nathan S. Corbin Rakesh K. Behera Veaceslav Coropceanu Curt A. Richter Christina A. Hacker Tatsuo Hasegawa Oana D. Jurchescu 《Advanced Electronic Materials》2016,2(10)
The organic charge‐transfer complex dibenzotetrathiafulvalene–7,7,8,8‐tetracyanoquinodimethane is found to crystallize in two polymorphs when grown by physical vapor transport: the known α‐polymorph and a new structure, the β‐polymorph. Structural and elemental analysis via selected area electron diffraction, X‐ray photoelectron spectroscopy, and polarized IR spectroscopy reveal that the complexes have the same stoichiometry with a 1:1 donor: acceptor ratio, but exhibit unique unit cells. The structural variations result in significant differences in the optoelectronic properties of the crystals, as observed in the experiments and electronic‐structure calculations. Raman spectroscopy shows that the α‐polymorph has a degree of charge transfer of about 0.5e, while the β‐polymorph is nearly neutral. Organic field‐effect transistors fabricated on these crystals reveal that in the same device structure both polymorphs show ambipolar charge transport, but the α‐polymorph exhibits electron‐dominant transport while the β‐polymorph is hole‐dominant. Together, these measurements imply that the transport features result from differing donor–acceptor overlap and consequential varying in frontier molecular orbital mixing, as suggested theoretically for charge‐transfer complexes. 相似文献
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Significant anisotropic electrical conduction in organosilica films is achieved by long‐range orientation of electroactive perylene bisimide (PBI) moieties in the silica scaffold. A new PBI‐based organosilane precursor is designed with lyotropic liquid‐crystalline properties. The PBI precursor with triethoxysilylphenyl groups exhibits a hexagonal columnar phase in the presence of organic solvents. The lyotropic liquid‐crystalline behavior of the precursor enables the preparation of dip‐coated films consisting of uniaxially aligned columnar aggregates of the PBI precursor on the centimeter scale. The oriented structure is successfully fixed by in situ polycondensation, which yields insoluble, thermally stable PBI–silica hybrid films. The oriented organosilica films doped with hydrazine exhibit high electrical conductivities on the order of 10?2 S cm?1, which are at the highest level for organosilica materials, and are comparable to those of all‐organic PBI assemblies. Definite anisotropy of conductivities is also found for these films. The present results suggest that the induction of significant electrical properties in organic molecular assemblies is compatible with the structural stabilization by inorganic–organic hybridization. 相似文献
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Scott Himmelberger Javier Dacuña Jonathan Rivnay Leslie H. Jimison Thomas McCarthy‐Ward Martin Heeney Iain McCulloch Michael F. Toney Alberto Salleo 《Advanced functional materials》2013,23(16):2091-2098
The film thickness of one of the most crystalline and highest performing polymer semiconductors, poly(2,5‐bis(3‐tetradecylthiophen‐2‐yl)thieno[3,2‐b]thiophene) (PBTTT), is varied in order to determine the effects of interfaces and confinement on the microstructure and performance in organic field effect transistors (OFETs). Crystalline texture and overall film crystallinity are found to depend strongly on film thickness and thermal processing. The angular distribution of crystallites narrows upon both a decrease in film thickness and thermal annealing. These changes in the film microstructure are paired with thin‐film transistor characterization and shown to be directly correlated with variations in charge carrier mobility. Charge transport is shown to be governed by film crystallinity in films below 20 nm and by crystalline orientation for thicker films. An optimal thickness is found for PBTTT at which the mobility is maximized in unannealed films and where mobility reaches a plateau at its highest value for annealed films. 相似文献
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Wu‐Qiang Wu Fuzhi Huang Dehong Chen Yi‐Bing Cheng Rachel A. Caruso 《Advanced functional materials》2015,25(21):3264-3272
To achieve high‐performance perovskite solar cells, especially with mesoscopic cell structure, the design of the electron transport layer (ETL) is of paramount importance. Highly branched anatase TiO2 nanowires (ATNWs) with varied orientation are grown via a facile one‐step hydrothermal process on a transparent conducting oxide substrate. These films show good coverage with optimization obtained by controlling the hydrothermal reaction time. A homogeneous methylammonium lead iodide (CH3NH3PbI3) perovskite thin film is deposited onto these ATNW films forming a bilayer architecture comprising of a CH3NH3PbI3 sensitized ATNW bottom layer and a CH3NH3PbI3 capping layer. The formation, grain size, and uniformity of the perovskite crystals strongly depend on the degree of surface coverage and the thickness of the ATNW film. Solar cells constructed using the optimized ATNW thin films (220 nm in thickness) yield power conversion efficiencies up to 14.2% with a short‐circuit photocurrent density of 20.32 mA cm?2, an open‐circuit photovoltage of 993 mV, and a fill factor of 0.70. The dendritic ETL and additional perovskite capping layer efficiently capture light and thus exhibit a superior light harvesting efficiency. The ATNW film is an effective hole‐blocking layer and efficient electron transport medium for excellent charge separation and collection within the cells. 相似文献
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Optical‐electrical duple bistable switches are those that enable simultaneous conversion of both optical and electrical signals in one device to realize seamless integration. Herein, imidazolium‐FCrO3 can be prepared into a large‐size single crystal and ultraflexible thin film with ultrahigh unidirectionality of (0 0 4) and is characterized through scanning electron microscopy (SEM), atomic force microscopy (AFM), powder X‐ray diffraction, etc. Both the thin film and crystal display synchronously eximious optoelectronic duple characteristics (dielectric and nonlinear optical second harmonic generation (SHG) bistable switching ON/OFF), with a record‐high SHG contrast of ≈250 (2.0 times that of KDP, potassium dihydrogen phosphate, exceeding all the known molecular materials/crystalline switches, revealing its potential to obtain high‐efficiency signal‐to‐noise ratio), sensitive dielectric bistability, and remarkable switching antifatigue. These attributes make imidazolium‐FCrO3 a potential candidate in photoelectric seamless integration devices and flexible multifunctional devices. 相似文献
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Duc T. Duong Victor Ho Zhengrong Shang Sonya Mollinger Stefan C.B. Mannsfeld Javier Dacuña Michael F. Toney Rachel Segalman Alberto Salleo 《Advanced functional materials》2014,24(28):4515-4521
In this work, crystallization kinetics and aggregate growth of poly(3‐ethylhexylthiophene) (P3EHT) thin films are studied as a function of film thickness. X‐ray diffraction and optical absorption show that individual aggregates and crystallites grow anisotropically and mostly along only two packing directions: the alkyl stacking and the polymer chain backbone direction. Further, it is also determined that crystallization kinetics is limited by the reorganization of polymer chains and depends strongly on the film thickness and average molecular weight. Time‐dependent, field‐effect hole mobilities in thin films reveal a percolation threshold for both low and high molecular weight P3EHT. Structural analysis reveals that charge percolation requires bridged aggregates separated by a distance of ≈2–3 nm, which is on the order of the polymer persistence length. These results thus highlight the importance of tie molecules and inter‐aggregate distance in supporting charge percolation in semiconducting polymer thin films. The study as a whole also demonstrates that P3EHT is an ideal model system for polythiophenes and should prove to be useful for future investigations into crystallization kinetics. 相似文献
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Single Crystal Microwires of p‐DTS(FBTTh2)2 and Their Use in the Fabrication of Field‐Effect Transistors and Photodetectors 
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下载免费PDF全文 Qiuhong Cui Yuanyuan Hu Cheng Zhou Feng Teng Jianfei Huang Andriy Zhugayevych Sergei Tretiak Thuc‐Quyen Nguyen Guillermo C. Bazan 《Advanced functional materials》2018,28(4)
Single crystal microwires of a well‐studied organic semiconductor used in organic solar cells, namely p‐DTS(FBTTh2)2, are prepared via a self‐assembly method in solution. The high level of intermolecular organization in the single crystals facilitates migration of charges, relative to solution‐processed films, and provides insight into the intrinsic charge transport properties of p‐DTS(FBTTh2)2. Field‐effect transistors based on the microwires can achieve hole mobilities on the order of ≈1.8 cm2 V?1 s?1. Furthermore, these microwires show photoresponsive electrical characteristics and can act as photoswitches, with switch ratios over 1000. These experimental results are interpreted using theoretical simulations using an atomistic density functional theory approach. Based on the lattice organization, intermolecular couplings and reorganization energies are calculated, and hole mobilities for comparison with experimental measurements are further estimated. These results demonstrate a unique example of the optoelectronic applications of p‐DTS(FBTTh2)2 microwires. 相似文献
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Phototransistors: High‐Performance UV–Vis–NIR Phototransistors Based on Single‐Crystalline Organic Semiconductor–Gold Hybrid Nanomaterials (Adv. Funct. Mater. 6/2017) 下载免费PDF全文
下载免费PDF全文 Ji Hyung Jung Min Ji Yoon Ju Won Lim Yoon Ho Lee Kang Eun Lee Dong Ha Kim Joon Hak Oh 《Advanced functional materials》2017,27(6)
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Louisa M. Smieska Vladimir A. Pozdin Justin L. Luria Richard G. Hennig Melissa A. Hines Chad A. Lewis John A. Marohn 《Advanced functional materials》2012,22(24):5096-5106
Charge trapping is one of several factors that limit the performance of organic electronic materials, yet even in pentacene, a prototypical small‐molecule semiconductor, the precise chemical nature of charge trapping remains poorly understood. Here the effects of three chemical trap‐precursor candidates are examined by layering thin‐film pentacene transistors with different pentacene defect species. The resulting charge trapping is studied in each device via scanning‐probe electric force microscopy coupled with variable‐wavelength sample illumination. Firstly, it is found that layering with pentacen‐6(13H)‐one (PHO) readily produces uniform charge trapping everywhere in the transistor channel, as expected for an active blanket‐deposited trap‐precursor. However, layering with 6,13‐dihydropentacene (DHP) produces fewer, more‐isolated traps, closely resembling the surface potential distribution in pristine pentacene thin films. Secondly, the rates of trap‐clearing versus illuminating wavelength (trap‐clearing spectra) are measured, revealing enhanced trap‐clearing rates at wavelengths assigned to the absorption of either pentacene or the charged trap species. The trap‐clearing spectrum for the PHO‐layered sample closely resembles the spectrum obtained from pentacene aged in a working transistor, while the trap‐clearing spectrum for the DHP‐layered sample resembles the spectrum observed in pristine pentacene. We conclude that PHO competently creates traps in pentacene that match the expected trap‐clearing spectrum for degraded pentacene, while DHP does not, and that the chemical trap species in aged pentacene is very likely PHO+. 相似文献
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Jung Ah Lim Hwa Sung Lee Wi Hyoung Lee Kilwon Cho 《Advanced functional materials》2009,19(10):1515-1525
Solution‐processable functionalized acenes have received special attention as promising organic semiconductors in recent years because of their superior intermolecular interactions and solution‐processability, and provide useful benchmarks for organic field‐effect transistors (OFETs). Charge‐carrier transport in organic semiconductor thin films is governed by their morphologies and molecular orientation, so self‐assembly of these functionalized acenes during solution processing is an important challenge. This article discusses the charge‐carrier transport characteristics of solution‐processed functionalized acene transistors and, in particular, focuses on the fine control of the films' morphologies and structural evolution during film‐deposition processes such as inkjet printing and post‐deposition annealing. We discuss strategies for controlling morphologies and crystalline microstructure of soluble acenes with a view to fabricating high‐performance OFETs. 相似文献
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Jianhang Guo Sai Jiang Mengjiao Pei Yanling Xiao Bowen Zhang Qijing Wang Ying Zhu Hengyuan Wang Jiansheng Jie Xinran Wang Yi Shi Yun Li 《Advanced Electronic Materials》2020,6(6)
Organic UV photodetectors using a transistor architecture can yield higher photoresponsivity than diode‐based devices because of the presence of a gate electrode. However, a long‐term issue of these phototransistor devices is the slow response speed, which hinders their practical applications. Here, organic UV phototransistors are constructed using few‐layer organic crystalline van der Waals (vdW) heterojunctions as the photoactive layers. The thickness of the photoactive layers is even less than the exciton diffusion length, thus removing the exciton‐diffusion bottleneck and giving rise to the confinement of charge separation and recombination within the adjacent molecular layers across the heterojunction interface. Hence, the phototransistor devices can exhibit a remarkably enhanced response speed (rise and decay times as short as only ≈4 and 6 ms, respectively). The layer‐dependent photoresponse characteristics are also observed, reinforcing the great importance of few‐layer organic heterostructures in phototransistor devices. This work not only provides a promising avenue toward fast response optoelectronic devices but also presents an in‐depth understanding on the microscopic nature of photogenerated charge carriers at the precision of molecular layers. 相似文献
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Ji Hyung Jung Min Ji Yoon Ju Won Lim Yoon Ho Lee Kang Eun Lee Dong Ha Kim Joon Hak Oh 《Advanced functional materials》2017,27(6)
Hybrid materials in optoelectronic devices can generate new functionality or provide synergistic effects that enhance the properties of each component. Here, high‐performance phototransistors with broad spectral responsivity in UV–vis–near‐infrared (NIR) regions, using gold nanorods (Au NRs)‐decorated n‐type organic semiconductor and N ,N ′‐bis(2‐phenylethyl)‐perylene‐3,4:9,10‐tetracarboxylic diimide (BPE‐PTCDI) nanowires (NWs) are reported. By way of the synergistic effect of the excellent photo‐conducting characteristics of single‐crystalline BPE‐PTCDI NW and the light scattering and localized surface plasmon resonances (LSPR) of Au NRs, the hybrid system provides new photo‐detectivity in the NIR spectral region. In the UV–vis region, hybrid nanomaterial‐based phototransistors exhibit significantly enhanced photo‐responsive properties with a photo‐responsivity (R ) of 7.70 × 105 A W?1 and external quantum efficiency (EQE) of 1.42 × 108% at the minimum light intensity of 2.5 µW cm?2, which are at least tenfold greater than those of pristine BPE‐PTCDI NW‐based ones and comparable to those of high‐performance inorganic material‐based devices. While a pristine BPE‐PTCDI NW‐based photodetector is insensitive to the NIR spectral region, the hybrid NW‐based phototransistor shows an R of 10.7 A W?1 and EQE of 1.35 × 103% under 980 nm wavelength‐NIR illumination. This work demonstrates a viable approach to high‐performance photo‐detecting systems with broad spectral responsivity. 相似文献
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Shu-Jen Wang Anton Kirch Michael Sawatzki Tim Achenbach Hans Kleemann Sebastian Reineke Karl Leo 《Advanced functional materials》2023,33(14):2213768
Conventional organic optoelectronic devices suffer from low carrier mobility limited by the static and dynamic disorder. Organic crystals with long-range order can circumvent the effects of disorder and significantly improve the charge transport. While highly ordered organic crystals offer the desirable electronic coupling strength and charge transport, their integration into large-area optoelectronic devices remains a challenge. Here, monolithic integrated triclinic crystal rubrene light-emitting diodes (LEDs) are presented using epitaxial growth with functional additives being engineered into the films. Superior charge transport, excellent operational and long-term stability in these light-emitting devices are demonstrated. By comparing two rubrene-based LEDs, one made from amorphous and one from crystalline rubrene layers, their exciton dynamics are estimated using comprehensive transient electroluminescence simulation. The crystalline LEDs show high triplet-triplet annihilation (TTA) rate constant similar to TTA rate constant of triclinic single crystals determined by optical spectroscopy. At the same time, the crystalline phase enhances drastically the singlet-fission and bimolecular annihilation rates, which reduces the overall performance of the LED compared to its amorphous counterpart. Finally, an outlook on the potential applications of rubrene and/or its derivatives crystalline films are provided for enhancing the performance of organic and hybrid optoelectronic devices. 相似文献
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Uijin Jeong Gergely Tarsoly Junghyun Lee Youngmoo Eun Junghwan Do Seungmoon Pyo 《Advanced Electronic Materials》2019,5(4)
The formation and characterization of interdigitated ambipolar active layers prepared by a hybrid (solution processing and thermal vacuum evaporation) method for a polymer‐gated organic phototransistor with highly balanced ambipolar charge transport is reported. The interdigitated active layer is comprised of a solution‐processed single‐crystalline microcrystal array of p‐type 6,13‐bis(triisopropylsilylethynyl)pentacene (TIPS‐pentacene) and a thin film of n‐type N,N′‐ditridecylperylene‐3,4,9,10‐tetracarboxylic diimide (PTCDI‐C13). The TIPS‐pentacene single‐crystalline microcrystal, which is confirmed using X‐ray diffractometry and polarized optical microscopy, is embedded in the PTCDI‐C13 film deposited using a thermal vacuum evaporation method. The devices with the interdigitated active layer exhibit selective charge transport characteristics varying from unipolar to ambipolar depending on the thickness of the PTCDI‐C13 film. The fabricated ambipolar organic transistor shows high photoresponsivity at low light intensities and good dynamic photoresponse. These results demonstrate the potential use of such devices in ambipolar optoelectronic applications. 相似文献