Enhanced Horizontal Dipole Orientation by Novel Penta-Helicene Anthracene-Based Host for Efficient Blue Fluorescent OLEDs

Due to the relatively low photoluminescence quantum yield (PLQY) and horizontal dipole orientation of doped films, anthracene-based fluorescent organic light-emitting diodes (F-OLEDs) have faced a great challenge to achieve high external quantum efficiency (EQE). Herein, a novel approach is introduced by incorporating penta-helicene into anthracene, presented as linear-shaped 3-(4-(10-phenylanthracen-9-yl)phenyl)dibenzo[c,g]phenanthrene (BABH) and 3-(4-(10-(naphthalen-2-yl)anthracen-9-yl)phenyl)dibenzo[c,g]phenanthrene (NABH). These blue hosts exhibit minimal intermolecular overlap of π-π stacking, effectively suppressing excimer formation, which facilitates the effective transfer of singlet energy to the fluorescent dopant for PLQY as high as 90%. Additionally, the as-obtained two hosts of BABH and NABH have effectively demonstrated major horizontal components transition dipole moments (TDM) and high thermal stability with glass transitional temperature (Tg ) surpassing 188 °C, enhancing the horizontal dipole orientation of their doped films to be 89% and 93%, respectively. The OLEDs based on BABH and NABH exhibit excellent EQE of 10.5% and 12.4% at 462 nm and device lifetime up to 90% of the initial luminance over 4500 h at 100 cd m-2 , which has firmly established them as among the most efficient blue F-OLEDs based on anthracene to date to the best knowledge. This work provides an instructive strategy to design an effective host for highly efficient and stable F-OLEDs.

[Profiling of Targeted miRNAs (8-nt) for the Genes Involved in Type 2 Diabetes Mellitus and Cardiac Hypertrophy]

Type 2 Diabetes Mellitus (T2DM) and cardiac hypertrophy (CH) are among the top ten leading cause of deaths, worldwide. T2DM and cardiac hypertrophy are the chronic diseases, have close association and direct life-threatening complications like stroke, myocardial infarction, retinopathy, nephropathy, and limb amputation. In addition to other medical approaches, miRNAs-based strategy is considered most efficient for early detection of chronic diseases and also has potential for the treatment of T2DM and cardiac hypertrophy like it is being used for cancer in clinical trials. MicroRNAs (miRNAs) are single stranded (non-coding) of 20 to 22 nucleotides sequences which bind to their target mRNA upon the complimentary basis, to silence the protein expression at post transcriptional level. Bioinformatic databases are used like online mendelian inheritance in man (OMIM), gene testing registry (GTR), TargetScan and ShinyGO for validation of disease linked genes and sorting the common miRNAs in both diseases, such as miR-30-5p/101-3p.2/190-5p/506-3p/9-5p/128-3p/137/96-5p/7-5p/107/101-3p.1/98-5p/124-3p.2/124-3p.116-5p/15-5p/497-5p/ 424-5p/195-5p/1271-5p, let-7-5p. Aforementioned databases were also used for the miRNAs which have more than one disease linked genes target in each pathological condition. Such miRNAs for cardiac hypertrophy are: miR-19-3p/183-5p.2/153-3p/372-3p/302-3p/520-3p/373-3p/129-5p/144-3p/139-5p and for T2DM are: miR-27-3p/206/1-3p/181-5p. This finding would be helpful for the appropriate selection of miRNAs and to design applicable research project in future. It will require more validation by using the miRNAs expression analysis, mimic, and anti-miRNA approach to check their potential against cardiac hypertrophy and T2DM.

Investigating the Thermal Stability of Organic Thin-Film Transistors and Phototransistors Based on [1]-Benzothieno-[3,2-b]-[1]-benzothiophene Dimeric Derivatives

Two new highly thermally stable [1]benzothieno[3,2-b][1]benzothiophene (BTBT) dimeric derivatives, namely 1,4-bis([1]benzothieno[3,2-b][1]benzothiophene-2-yl)benzene (BTBT-Ph-BTBT) and 4,4'-bis([1]benzothieno[3,2-b][1]benzothiophene-2-yl)-1,1'-biphenyl (BTBT-DPh-BTBT), were synthesized by combining two simple fragment structures. Compared to the monomer compound 2-phenyl[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT, μ_max =3.4×10^-2  cm²  V^-1  s^-1 ), the organic thin-film transistors (OTFTs) based on BTBT-Ph-BTBT and BTBT-DPh-BTBT showed significantly higher mobility (up to 2.5 and 3.6 cm²  V^-1  s^-1 for BTBT-Ph-BTBT and BTBT-DPh-BTBT, respectively). The mobility of OTFTs based on BTBT-Ph-BTBT was kept at a high value (2.4×10^-1  cm²  V^-1  s^-1 ) after the devices were thermally annealed at 350 °C. Furthermore, the organic phototransistors (OPTs) based on BTBT-Ph-BTBT and BTBT-DPh-BTBT displayed high photosensitivities in a range of 250-400 nm with a low intensity, making these materials potentially applicable for sensitive optoelectronic devices.

Dosimetric effect of limited aperture multileaf collimator on VMAT plan quality: A study of prostate and head-and-neck cancers

AIM

The aim of study was to evaluate the dosimetric effect of collimator-rotation on VMAT plan quality, when using limited aperture multileaf collimator of Elekta Beam Modulator™ providing a maximum aperture of 21 cm × 16 cm.

BACKGROUND

The increased use of VMAT technique to deliver IMRT from conventional to very specialized treatments present a challenge in plan optimization. In this study VMAT plans were optimized for prostate and head and neck cancers using Elekta Beam-Modulator^TM, whereas previous studies were reported for conventional Linac aperture.

MATERIALS AND METHODS

VMAT plans for nine of each prostate and head-and-neck cancer patients were produced using the 6 MV photon beam for Elekta-SynergyS^® Linac using Pinnacle³ treatment planning system. Single arc, dual arc and two combined independent-single arcs were optimized for collimator angles (C) 0°, 90° and 0°-90° (0°-90°; i.e. the first-arc was assigned C0° and second-arc was assigned C90°). A treatment plan comparison was performed among C0°, C90° and C(0°-90°) for single-arc dual-arc and two independent-single-arcs VMAT techniques to evaluate the influence of extreme collimator rotations (C0° and 90°) on VMAT plan quality. Plan evaluation criteria included the target coverage, conformity index, homogeneity index and doses to organs at risk. A 'two-sided student t-test' (p ≤ 0.05) was used to determine if there was a significant difference in dose volume indices of plans.

RESULTS

For both prostate and head-and-neck, plan quality at collimator angles C0° and C(0°-90°) was clinically acceptable for all VMAT-techniques, except SA for head-and-neck. Poorer target coverage, higher normal tissue doses and significant p-values were observed for collimator angle 90° when compared with C0° and C(0°-90°).

CONCLUSIONS

A collimator rotation of 0° provided significantly better target coverage and sparing of organs-at-risk than a collimator rotation of 90° for all VMAT techniques.

Highly Simplified Tandem Organic Light-Emitting Devices Incorporating a Green Phosphorescence Ultrathin Emitter within a Novel Interface Exciplex for High Efficiency

Herein we report a novel design philosophy of tandem OLEDs incorporating a doping-free green phosphorescent bis[2-(2-pyridinyl-N)phenyl-C](acetylacetonato)iridium(III) (Ir(ppy)₂(acac)) as an ultrathin emissive layer (UEML) into a novel interface-exciplex-forming structure of 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) and 1,3,5-tri(p-pyrid-3-yl-phenyl)benzene (TmPyPB). Particularly, relatively low working voltage and remarkable efficiency are achieved and the designed tandem OLEDs exhibit a peak current efficiency of 135.74 cd/A (EQE = 36.85%) which is two times higher than 66.2 cd/A (EQE = 17.97%) of the device with a single emitter unit. This might be one of the highest efficiencies of OLEDs applying ultrathin emitters without light extraction. Moreover, with the proposed structure, the color gamut of the displays can be effectively increased from 76% to 82% NTSC if the same red and blue emissions as those in the NTSC are applied. A novel form of harmonious fusion among interface exciplex, UEML, and tandem structure is successfully realized, which sheds light on further development of ideal OLED structure with high efficiency, simplified fabrication, low power consumption, low cost, and improved color gamut, simultaneously.

Thermal and Optical Modulation of the Carrier Mobility in OTFTs Based on an Azo-anthracene Liquid Crystal Organic Semiconductor

One of the most striking features of organic semiconductors compared with their corresponding inorganic counterparts is their molecular diversity. The major challenge in organic semiconductor material technology is creating molecular structural motifs to develop multifunctional materials in order to achieve the desired functionalities yet to optimize the specific device performance. Azo-compounds, because of their special photoresponsive property, have attracted extensive interest in photonic and optoelectronic applications; if incorporated wisely in the organic semiconductor groups, they can be innovatively utilized in advanced smart electronic applications, where thermal and photo modulation is applied to tune the electronic properties. On the basis of this aspiration, a novel azo-functionalized liquid crystal semiconductor material, (E)-1-(4-(anthracen-2-yl)phenyl)-2-(4-(decyloxy)phenyl)diazene (APDPD), is designed and synthesized for application in organic thin-film transistors (OTFTs). The UV-vis spectra of APDPD exhibit reversible photoisomerizaton upon photoexcitation, and the thin films of APDPD show a long-range orientational order based on its liquid crystal phase. The performance of OTFTs based on this material as well as the effects of thermal treatment and UV-irradiation on mobility are investigated. The molecular structure, stability of the material, and morphology of the thin films are characterized by thermal gravimetric analysis (TGA), polarizing optical microscopy (POM), (differential scanning calorimetry (DSC), UV-vis spectroscopy, atomic force microscopy (AFM), and scanning tunneling microscopy (STM). This study reveals that our new material has the potential to be applied in optical sensors, memories, logic circuits, and functional switches.

Highly Simplified Reddish Orange Phosphorescent Organic Light-Emitting Diodes Incorporating a Novel Carrier- and Exciton-Confining Spiro-Exciplex-Forming Host for Reduced Efficiency Roll-off

A novel exciplex-forming host is applied so as to design highly simplified reddish orange light-emitting diodes (OLEDs) with low driving voltage, high efficiency, and an extraordinarily low efficiency roll-off, by combining N,N-10-triphenyl-10H-spiro [acridine-9,9'-fluoren]-3'-amine (SAFDPA) with 4,7-diphenyl-1,10-phenanthroline (Bphen) doped with trivalent iridium complex bis(2-methyldibenzo[f,h]quinoxaline) (acetylacetonate)iridium(III) (Ir(MDQ)₂(acac)). The reddish orange OLEDs achieve a strikingly high power efficiency (PE) of 31.80 lm/W with an ultralow threshold voltage of 2.24 V which is almost equal to the triplet energy level of the phosphorescent reddish orange emitting dopant. The power efficiency of the device with the exciplex-forming host is enhanced, achieving 36.2% mainly owing to the lower operating voltage by the novel exciplex forming cohost, compared with the reference device (23.54 lm/W). Moreover, the OLEDs show extraordinarily low current efficiency (CE) roll-off to 1.41% at the brightness from 500 to 5000 cd/m² with a maximal CE of 32.87 cd/A (EQE_max = 11.01%). The devices display a good reddish orange color (CIE of (0.628, 0.372) at 500 cd/m²) nearly without color shift with increasing brightness. Co-host architecture phosphorescent OLEDs show a simpler device structure, lower working voltage, and a better efficiency and stability than those of the reference devices without the cohost architecture, which helps to simplify the OLED structure, lower the cost, and popularize OLED technology.

Thin film transistors based on two dimensional graphene and graphene/semiconductor heterojunctions

During the past few years, two-dimensional (2D) layered materials have emerged as the most fundamental building blocks of a wide variety of optoelectronic devices.

Exploring the electrochromic properties of poly(thieno[3,2-b]thiophene)s decorated with electron-deficient side groups

Electron-deficient cyanophenyl side groups decrease the response time and drastically improve the stability of electrochromic polymers.

Design and characterization of methoxy modified organic semiconductors based on phenyl[1]benzothieno[3,2-b][1]benzothiophene

Two environmentally and thermally stable [1]benzothieno[3,2-b][1]benzothiophene (BTBT) derivatives, BOP-BTBT and DBOP-BTBT are successfully synthesized and analyzed as active layers in organic thin film transistors.

A Unique Blend of 2-Fluorenyl-2-anthracene and 2-Anthryl-2-anthracence Showing White Emission and High Charge Mobility

White-light-emitting materials with high mobility are necessary for organic white-light-emitting transistors, which can be used for self-driven OLED displays or OLED lighting. In this study, we combined two materials with similar structures-2-fluorenyl-2-anthracene (FlAnt) with blue emission and 2-anthryl-2-anthracence (2A) with greenish-yellow emission-to fabricate OLED devices, which showed unusual solid-state white-light emission with the CIE coordinates (0.33, 0.34) at 10 V. The similar crystal structures ensured that the OTFTs based on mixed FlAnt and 2A showed high mobility of 1.56 cm²  V^-1  s^-1 . This simple method provides new insight into the design of high-performance white-emitting transistor materials and structures.

Electric Properties of Organic-on-Inorganic n-Si/VOPc Heterojunction

In the current study vanadyl-phthalocyanine (VOPc) thin films were deposited by vacuum evaporation on n-Si substrate resulting in an organic-on-inorganic (n-Si/VOPc) heterojunctions. Ag films were deposited as electrodes. Thicknesses of the VOPc films were in the range of 100-300 nm. The dark I-V characteristics exhibited rectification behavior. The rectification ratio (RR) decreased from 4 to 0.4 as the thickness of the VOPc film decreased. The dark I-V characteristics were simulated by modified Schokley equation and spaace-charge limited currents (SCLC) approach. Investigations were carried out to study the effect of VOPc films thickness on reverse saturation current , diode quality factor and mobility of charge carriers.

Molecular phase engineering of organic semiconductors based on a [1]benzothieno[3,2-b][1]benzothiophene core

Liquid crystalline material C6-Ph-BTBT exhibits higher mobility than that of the non-liquid crystalline material Ph-BTBT under the same conditions.

Highly transmissive blue electrochromic polymers based on thieno[3,2-b]thiophene

Polymers based on a thieno[3,2-b]thiophene core modulated by alkylphenyl groups show high optical contrast and deep blue to highly transmissive electrochromic performances.

Thieno[3,2-b]thiophene based electrochromic polymers: experimental cum theoretical appraisal of the EDOT position

P(2,5-BTE) reflects color from purple to grey-blue, while P(3,6-BTE) switches from orange-red to cyan.

Unlocking the potential of diketopyrrolopyrrole-based solar cells by a pre-solvent annealing method in all-solution processing

A novel synthetic route for a diketopyrrolopyrrole-based DPP-ANT donor material is demonstrated and applied in polymer photovoltaics. The power conversion efficiency is more than four times that of an unannealed device.

Insulin over expression induces heart abnormalities via reactive oxygen species regulation, might be step towards cardiac hypertrophy

Insulin is known to regulate blood—glucose level and promote its utilization as an energy source in cardiac tissues under normal physiological conditions as well as stimulates signaling pathways that involved cell growth and proliferation. Although recently insulin generated free radicals via NAD(P)H has been documented but the molecular mechanism is still under investigation. The aim of present study is to elucidate the reactive oxygen species (ROS) dependent possible role of insulin in cardiac abnormalities, including hypertrophy by regulation of antioxidants enzyme (SOD) activity. In the current study, 60 cardiac patients and 50 healthy individuals as well as the rat model with insulin administration were under investigation. Oxidant, anti—oxidant biochemical assays, hypertrophic marker expression via immunobloting and histopathology were performed. We observed statistically significant elevation of the reactive oxygen species level in the serum of patients as well as in the insulin administrated rat model, a mild expression of cardiac marker in experimental models along with abnormal histopathology of hearts. However, super oxide dismutase free radical scavenger activity was down regulated upon insulin treatment compared to control rats. Conclusively, the present study showed that over expression of insulin might stimulate cardiac hypertrophic signal via up regulation of free radicals and down regulation of antioxidants enzymes including SOD activity.

Cardiac hypertrophy is negatively regulated by miR-541

Heart failure is a leading cause of death in aging population. Cardiac hypertrophy is an adaptive reaction of the heart against cardiac overloading, but continuous cardiac hypertrophy is able to induce heart failure. We found that the level of miR-541 was decreased in angiotensin II (Ang-II) treated cardiomyocytes. Enforced expression of miR-541 resulted in a reduced hypertrophic phenotype upon Ang-II treatment in cellular models. In addition, we generated miR-541 transgenic mice that exhibited a reduced hypertrophic response upon Ang-II treatment. Furthermore, we found miR-541 is the target of microphthalmia-associated transcription factor (MITF) in the hypertrophic pathway and MITF can negatively regulate the expression of miR-541 at the transcriptional levels. MITF(ce/ce) mice exhibited a reduced hypertrophic phenotype upon Ang-II treatment. Knockdown of MITF also results in a reduction of hypertrophic responses after Ang-II treatment. Knockdown of miR-541 can block the antihypertrophic effect of MITF knockdown in cardiomyocytes upon Ang-II treatment. This indicates that the effect of MITF on cardiac hypertrophy relies on the regulation of miR-541. Our present study reveals a novel cardiac hypertrophy regulating pathway that was composed of miR-541 and MITF. Modulation of their levels may provide a new approach for tackling cardiac hypertrophy.