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Yen-Wei Jhou, Chun-Kai Yang, Siang-Yu Sie, Hsiang-Chih Chiu, Jyh-Shen Tsay
Investigations exploring the inherent mechanical properties of electronic materials have grown rapidly in recent years largely because they are important in developing flexible electronics, organic displays and sensors. However, our understanding of the mechanical properties of organic semiconductors with a thin-film form remains limited. We report herein on an investigation of the structures and related elastic moduli perpendicular to the surface of a rubrene thin film. A rubrene/Si(100) film typically has a cluster-type morphology mainly comprising crystalline nanodomains within the film...
February 13, 2019: Physical Chemistry Chemical Physics: PCCP
Keisuke Yano, Hiroyuki Katsuki, Hisao Yanagi
Organic molecular crystals have a variety of low frequency vibrational modes composed of intra- and inter-molecular oscillations. They are mixed intricately in the terahertz (THz) region. We are interested in the controllability of the vibrational energy distribution among such THz vibrational modes based on the femtosecond double-pulse excitation scheme. Single crystalline rubrene is prepared by physical vapor transport. The optical response of vibrational modes in the electric ground state of rubrene is detected by the ultrafast pump-probe reflectivity measurement at 90 K...
February 7, 2019: Journal of Chemical Physics
Sebastian Engmann, Adam J Barito, Emily G Bittle, Noel C Giebink, Lee J Richter, David J Gundlach
Spin-dependent nonlinear processes in organic materials such as singlet-fission and triplet-triplet annihilation could increase the performance for photovoltaics, detectors, and light emitting diodes. Rubrene/C60 light emitting diodes exhibit a distinct low voltage (half-bandgap) threshold for emission. Two origins for the low voltage turn-on have been proposed: (i) Auger assisted energy up-conversion, and (ii) triplet-triplet annihilation. We test these proposals by systematically altering the rubrene/C60 interface kinetics by introducing thin interlayers...
January 16, 2019: Nature Communications
Fang-Qi Hu, Qing Zhao, Xu-Biao Peng
Singlet fission (SF) materials are a kind of promising material for breaking the solar cell efficiency limit. Here we rebuild the four-electron spin Hamiltonian under our coordinate system and present an improved model described by the population evolution equations on fluorescence decay (FD) dynamics that contain several detailed physical processes. The improved model for total random molecular orientation gives a more consistent fitting on the experimental data [G. B. Piland et al., J. Phys. Chem. C, 2013, 117, 1224] about time-resolved FD of amorphous rubrene thin films in the presence of a strong magnetic field...
January 15, 2019: Physical Chemistry Chemical Physics: PCCP
Ryohei Tsuruta, Takuya Hosokai, Soichiro Yamanaka, Koki Yoshida, Yuta Mizuno, Tomoyuki Koganezawa, Yasuo Nakayama
Uniform and well-defined interfaces are required for clarification of fundamental processes at internal interfaces between donor and acceptor molecules constituting organic optoelectronic devices. In this study, evolution of a well-ordered molecular interface, epitaxially grown C60 on the single crystal rubrene (C42H28) surface, was accurately investigated by grazing incidence X-ray diffraction (GIXD) techniques. Contrasting to the case of C60 on the single crystal pentacene forming uniquely aligned epitaxial interfaces, coexistence of two inequivalent crystalline domains of C60 was identified on the single crystal rubrene...
January 11, 2019: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Min Zhao, Lijuan Bai, Wei Cheng, Xiaolei Duan, Haiping Wu, Shijia Ding
Only surficial molecules of eletrochemiluminescent (ECL) nanomaterials are the most reactive species in the typical ECL reaction. Herein, monolayer rubrene was assembled on the surface of graphene sheet to obtain monolayer rubrene functionalized graphene composite (G/mRub) with strong ECL emission by maximizing the surficial rubrene molecules. Based on G/mRub as the strong ECL emitter, an ultrasensitive "on-off" biosensor was developed to detect cystatin C (Cys C) in human serum with the help of a novel immunorecognition-induced enzyme-free 3D DNA machine...
December 15, 2018: Biosensors & Bioelectronics
Qianqian Du, Shuchao Qin, WenJun Wang, Yangyang Guo, Jiandong Ye, Shunming Zhu, Kun Tang, Rong Zhang, Youdou Zheng, Shulin Gu
ZnO nanowire photodetectors have attracted much attention due to their excellent optoelectronic performances. However, the operating speed remains a challenge, and the scalability is also impeded by the uncontrolled transfer methods and sophisticated fabrication process. In this paper, we have fabricated an excellent ZnO nanobridge ultraviolet photodetector array by using a simple one-step method. The faster photoresponse speed and a broader response wavelength (from UV to visible range) have been achieved by constructing a type-II ZnO/rubrene heterointerface...
November 19, 2018: Nanotechnology
Jiliang Zhang, George F S Whitehead, Troy D Manning, David Stewart, Craig I Hiley, Michael J Pitcher, Susanna Jansat, Kosmas Prassides, Matthew J Rosseinsky
We present the synthesis and characterization of the K+ intercalated rubrene (C42 H28 ) phase, K2 Rubrene (K2 R) and identify the co-existence of amorphous and crystalline materials in samples where the crystalline component is phase pure. We suggest this is characteristic of many intercalated alkali metal-polyaromatic hydrocarbon (PAH) systems, including those for which superconductivity has been claimed. The systematic investigation of K-rubrene solid state reactions using both K and KH sources reveals complex competition between K intercalation and the decomposition of rubrene, producing three K-intercalated compounds, namely, K2 R, K(RR*), and Kx R' (where R* and R' are rubrene decomposition derivatives C42 H26 and C30 H20 , respectively)...
November 30, 2018: Journal of the American Chemical Society
Kei Kitamura, Kenta Asahina, Yusaku Nagai, Keshu Zhang, Shogo Nomura, Katsunori Tanaka, Toshiyuki Hamura
A new synthetic route to 5,6,11,12-tetrakis(arylethynyl)tetracenes, π-extended rubrenes, was developed via [4 + 2] cycloadditions of dialkynylisobenzofuran and 1,4-naphthoquinone. Introduction of arylethynyl groups by double nucleophilic additions to tetracenequinone gave sterically congested (arylethynyl)tetracenes after reductive aromatization. The photophysical properties of the newly prepared π-conjugated molecules are also evaluated.
November 21, 2018: Organic & Biomolecular Chemistry
Marco J Pereira, Micaela Matta, Lionel Hirsch, Isabelle Dufour, Alejandro Briseno, Sai Manoj Gali, Yoann Olivier, Luca Muccioli, Alfred Crosby, Cédric Ayela, Guillaume Wantz
Micro-electromechanical systems (MEMS) made of organic materials have attracted efforts for the development a new generation of physical, chemical, and biological sensors, for which the electromechanical sensitivity is the current major concern. Here, we present an organic MEMS made of a rubrene single-crystal air-gap transistor. Applying mechanical pressure on the semiconductor results in high variations in drain current: an unparalleled gauge factor above 4000 has been measured experimentally. Such a high sensitivity is induced by the modulation of charge injection at the interface between the gold electrode and the rubrene semiconductor as an unusual transducing effect...
November 16, 2018: ACS Applied Materials & Interfaces
Shan-Shan Yang, Ming-Hui Jiang, Yaqin Chai, Ruo Yuan, Ying Zhuo
The accurate and rapid quantitative detection of antibodies had a significant influence in controlling and preventing diseases or toxins outbreaks. In this work, we first introduce the antibody-powered triplex-DNA nanomachine to release cargo DNA as substitute target for sensitive electrochemiluminescence (ECL) detection of anti-digoxigenin based on a novel ternary ECL system. It is worth noting that the cargo DNA as a substitute target of antibody can further participate in an enzyme-assisted cycling strand displacement reaction (CSDR) to achieve ECL signal amplification and improve the sensitivity of antibody detection...
October 11, 2018: ACS Applied Materials & Interfaces
Yusuke Wakabayashi, Masanari Nakamura, Kaori Sasaki, Takahiro Maeda, Yuutaro Kishi, Hiroyuki Ishii, Nobuhiko Kobayashi, Susumu Yanagisawa, Yuma Shimo, Yoshihiro Kubozono
Surface structure relaxation of organic semiconductors affects the properties of organic devices, although such relaxation has not been well explored. Only two examples have been experimentally reported; tetracene shows a large surface relaxation, while rubrene exhibits no relaxation. Therefore, a systematic investigation of the surface relaxation is conducted on [ n]phenacenes ( n = 5, 7, and 9). Electron density analyses are performed based on the synchrotron surface X-ray scattering with the aid of first-principles calculations...
October 31, 2018: Journal of the American Chemical Society
Chaojun Li, Xiaofeng Liu, Jianrong Qiu
Organic semiconductors, such as polycyclic aromatic hydrocarbons, are typically not responsive to near infrared (NIR) light due to their relatively large bandgaps. Here, we show that the NIR light at 980 nm can be efficiently converted to broadband visible upconversion (UC) emission by rubrene molecules in a solution dispersed with upconversion nanoparticles (UCNPs). Spectroscopic characterizations indicate that the sensitization of emission by rubrene molecules strongly depends on the location of the 4f levels of Er3+ ions and the interplay between reabsorption and Förster-type energy transfer...
November 7, 2018: Physical Chemistry Chemical Physics: PCCP
Shumei Li, Xu Li, Lizhong Wang, Hongbo Liu
A white organic light emitting device with structure of ITO/2T-NATA(20)/NPBX(15)/DPVBi(15)/ Alq:Rub(10, x)/Alq3(40)/LiF/Al was fabricated using doping rubrene. When the concentration of rubrene is 3 wt.%, the chromaticity is the best (0.319, 0.317), and the color coordinates are stable. When the thickness of the doping layer is 20 nm, the efficiency and luminance of the devices are the highest, which are 5.1022 cd/A and 17130 cd/m2, respectively. On the basis, a test system is consisted of Solomon's OLED display control driver chip SSD1306 and microcontroller AT89C52, which tests the OLED dot matrix through the program to determine whether the matrix has dead point...
December 1, 2018: Journal of Nanoscience and Nanotechnology
Cheol-Joon Park, Hyeon Jung Park, Jae Yoon Lee, Jeongyong Kim, Chul-Ho Lee, Jinsoo Joo
A several-layer n-type MoS2 was partially hybridized with an organic crystalline p-type rubrene nanosheet through van der Waals interactions to fabricate a two-dimensional (2-D) lateral-type n-p heterojunction optoelectronic device. The field-effect transistors (FETs) using lateral-type MoS2 /rubrene hybrids exhibited both gate-tunable diode and anti-ambipolar transistor characteristics. The FET devices show the coexistence of n-type states, p-type states, and off-states controlled by the gate bias. From the photocurrent mapping experiments, the gate-bias-dependent photovoltaic effect was observed from the heterojunction regions of the MoS2 /rubrene FETs...
September 5, 2018: ACS Applied Materials & Interfaces
Xinglong Ren, C Daniel Frisbie, Chris Leighton
Although electrolyte gating has been demonstrated to enable control of electronic phase transitions in many materials, long sought-after gate-induced insulator-metal transitions in organic semiconductors remain elusive. To better understand limiting factors in this regard, here we report detailed wide-range resistance-temperature ( R- T) measurements at multiple gate voltages on ionic-liquid-gated rubrene single crystals. Focusing on the previously observed high-bias regime where conductance anomalously decreases with increasing bias magnitude, we uncover two surprising (and related) features...
September 6, 2018: Journal of Physical Chemistry Letters
Jae Joon Kim, Stefan Bachevillier, D Leonardo Gonzalez Arellano, Benjamin P Cherniawski, Edmund K Burnett, Natalie Stingelin, Cédric Ayela, Özlem Usluer, Stefan C B Mannsfeld, Guillaume Wantz, Alejandro L Briseno
The relationship between charge transport and surface morphology is investigated by utilizing rubrene single crystals of varying thicknesses. In the case of pristine crystals, the surface conductivities decrease exponentially as the crystal thickness increases until ∼4 μm, beyond which the surface conductivity saturates. Investigation of the surface morphology using optical and atomic force microscopy reveals that thicker crystals have a higher number of molecular steps, increasing the overall surface roughness compared with thin crystals...
August 8, 2018: ACS Applied Materials & Interfaces
Ryo Nagata, Hajime Nakanotani, William J Potscavage, Chihaya Adachi
Harvesting of both triplets and singlets yields electroluminescence quantum efficiencies of nearly 100% in organic light-emitting diodes (OLEDs), but the production efficiency of excitons that can undergo radiative decay is theoretically limited to 100% of the electron-hole pairs. Here, breaking of this limit by exploiting singlet fission in an OLED is reported. Based on the dependence of electroluminescence intensity on an applied magnetic field, it is confirmed that triplets produced by singlet fission in a rubrene host matrix are emitted as near-infrared (NIR) electroluminescence by erbium(III) tris(8-hydroxyquinoline) (ErQ3 ) after excitonic energy transfer from the "dark" triplet state of rubrene to an "emissive" state of ErQ3 , leading to NIR electroluminescence with an overall exciton production efficiency of 100...
July 5, 2018: Advanced Materials
T Mukherjee, Sumona Sinha, M Mukherjee
X-ray absorption spectra (XAS), the density of states (DOS) and the electron density distribution of the HOMO and LUMO for flat and twisted rubrene molecules have been calculated using density functional theory (DFT). The simulated XAS spectra are validated by experimental C K-edge near-edge X-ray absorption fine structure (NEXAFS) data. We demonstrate that the NEXAFS spectra of rubrene thin films of different thicknesses can be explained in terms of different combinations of spectral intensity from the twisted and the flat randomly oriented molecules...
July 11, 2018: Physical Chemistry Chemical Physics: PCCP
Dong Wei, Fusheng Ma, Rui Wang, Shangyi Dou, Peng Cui, Hao Huang, Jun Ji, Endong Jia, Xiaojie Jia, Sajid Sajid, Ahmed Mourtada Elseman, Lihua Chu, Yingfeng Li, Bing Jiang, Juan Qiao, Yongbo Yuan, Meicheng Li
Migration of ions can lead to photoinduced phase separation, degradation, and current-voltage hysteresis in perovskite solar cells (PSCs), and has become a serious drawback for the organic-inorganic hybrid perovskite materials (OIPs). Here, the inhibition of ion migration is realized by the supramolecular cation-π interaction between aromatic rubrene and organic cations in OIPs. The energy of the cation-π interaction between rubrene and perovskite is found to be as strong as 1.5 eV, which is enough to immobilize the organic cations in OIPs; this will thus will lead to the obvious reduction of defects in perovskite films and outstanding stability in devices...
August 2018: Advanced Materials
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