Phototransistors based on multilayer MoS(2) crystals are demonstrated with a wider spectral response and higher photoresponsivity than single-layer MoS(2) phototransistors. Multilayer MoS(2) phototransistors further exhibit high room temperature mobilities (>70 cm(2) V(-1) s(-1) ), near-ideal subthreshold swings (~70 mV decade(-1) ), low operating gate biases (<5 V), and negligible shifts in the threshold voltages during illumination.

Sunkook Kim, Jinsoo Joo, and co‐workers demonstrate phototransistors based on multilayer MoS2 crystals with a wider spectral response and higher photoresponsivity than single‐layer MoS2 phototransistors. These multilayer MoS2 phototransistors also exhibit high room‐temperature mobilities, near‐ideal subthreshold swings, low operating gate biases, and negligible shifts in the threshold voltages during illumination.

The highly photosensitive characteristics of organic thin‐film transistors (OTFTs) made using soluble star‐shaped oligothiophenes with four‐armed π‐conjugation paths, 4(HPBT)‐benzene and 4(HP3T)‐benzene molecules having a relatively high quantum yield, are reported. 4(HPBT)‐benzene‐based organic phototransistors (OPTs) exhibited high photosensitivity (∼2500–4300 A W−1) even with low optical powers (∼6.8–30 µW cm−2) at zero gate bias. The measured photosensitivity of the devices was much higher than that of inorganic single‐crystal Si‐based phototransistors, as well as that of other OPTs reported earlier. With the highly photosensitive characteristics of the 4(HPBT)‐benzene‐based OPTs, a high ratio of the on and off current switching of ∼4 × 104 with low optical power and low gate bias was observed. The slow relaxation of the photoinduced charges and charge‐trapping phenomena at the interface could lead to a reproducible memory operation for 4(HPBT)‐benzene‐based OPTs.

This is a report on a new method of growth of a light‐emitting rubrene nanowires array with diameters of 200 ± 10 nm by using organic vapor transport through Al2O3 nanoporous templates. Nanometer‐scale laser confocal microscope (LCM) photoluminescence (PL) spectra and crystalline structures of the rubrene nanowires are compared with those of rubrene single crystals prepared with the same experimental conditions without the template. In the LCM PL spectra it is observed that the PL spectra and intensity varies with the detecting positions because of the crystal growth characteristics of the rubrene molecules. A single rubrene nanowire has a wider LCM PL band width than that of the rubrene single crystal. This may originate from the light emissions of the mixed polarized bands due to additional new crystallinity in the formation of the nanowires. From the current–voltage characteristic curves, the semiconducting nature of both the rubrene nanowires and single crystals is observed.

New star-shaped crystalline molecules have been synthesized through Horner-Emmons reactions using hexyl-substituted thiophene-based carbaldehydes as dendrons and [1,2,4,5-tetra-(diethoxy-phosphorylmethyl)-benzyl]-phosphonic acid diethyl ester as the core units; these molecules have been fully characterized. Three thiophene-based star-shaped molecules exhibit good solubility in common organic solvents and good self-film-forming properties. They are intrinsically crystalline as they exhibit well-defined X-ray diffraction patterns from uniform and preferred orientations of molecules. The semiconducting properties of the star-shaped molecules have been evaluated in organic field-effect transistors. Three crystalline conjugated molecules, 4, 8, and 12, exhibit carrier mobilities as high as 6.0 (±0.5) × 10-3, 2.5 (±0.5) × 10-4, and 2.5 (±0.5) × 10-2 cm2·V-1·s-1, respectively. The dithienothiophene dendrons in 12 induce easy crystallization and small crystallite formation even in as-cast films and can be found to densely cover the surface of a dielectric layer. This helps in attaining good network interconnection of the carrier transport channel, which is responsible for the relatively high carrier mobility in solution-processed organic semiconductors for OFET.

We fabricate hybrid coaxial nanotubes (NTs) of multiwalled carbon nanotubes (MWCNTs) coated with light-emitting poly(3-hexylthiophene) (P3HT). The p-type P3HT material with a thickness of approximately 20 nm is electrochemically deposited onto the surface of the MWCNT. The formation of hybrid coaxial NTs of the P3HT/MWCNT is confirmed by a transmission electron microscope, FT-IR, and Raman spectra. The optical and structural properties of the hybrid NTs are characterized using ultraviolet and visible absorption, Raman, and photoluminescence (PL) spectra where, it is shown that the PL intensity of the P3HT materials decreases after the hybridization with the MWCNTs. The current-voltage (I-V) characteristics of the outer P3HT single NT show the semiconducting behavior, while ohmic behavior is observed for the inner single MWCNT. The I-V characteristics of the hybrid junction between the outer P3HT NT and the inner MWCNT, for the hybrid single NT, exhibit the characteristics of a diode (i.e., rectification), whose efficiency is clearly enhanced with light irradiation. The rectification effect of the hybrid single NT has been analyzed in terms of charge tunneling models. The quasi-photovoltaic effect is also observed at low bias for the P3HT/MWCNT hybrid single NT.

Background and Objectives Riehl's melanosis is a chronic acquired hyperpigmentation disorder that causes significant cosmetic problems for patients with this condition. Several treatment options, including low‐fluence Q‐switched Nd:YAG (QSNY) 1064‐nm laser treatment, have been attempted with inconsistent results. We aimed to investigate the beneficial effect of mid‐fluence QSNY 1064‐nm laser in the treatment of Riehl's melanosis. Study Design/Materials and Methods A retrospective review was conducted on patients repetitively treated with mid‐fluence (3.5–5 J/cm2 with a spot size of 5 mm and a pulse rate of 10 Hz) QSNY 1064‐nm laser. Twenty‐one patients with Riehl's melanosis were involved. Clinical photographs, treatment parameters, and side effects were reviewed to assess the safety and efficacy of the modality. Results The mean age of the patients was 57.00 ±8.2 years, and there were 20 female patients and 1 male patient. The mean number of treatment sessions was 5.95 ± 3.6, and the mean interval between each session was 39.12 ± 13.4 days. After treatment, the mean melasma area and severity index score decreased from 12.53 ± 10.2 to 5.98 ± 5.3. At the final visit, 16 of the 21 (76.1%) patients were considered to have moderately or very much improved. No severe side effects were observed. Conclusions Repetitive mid‐fluence QSNY 1064‐nm laser treatment may be an effective and safe optional modality for Riehl's melanosis. Lasers Surg. Med. © 2020 Wiley Periodicals, Inc.

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