A new organic light-emitting field-effect transistor characterized by a metal oxide layer inserted between the organic layer and the gate insulator is proposed. The metal oxide is indirectly connected with source and drain electrodes through the organic layer. Upon increasing the potential difference between the source and drain electrodes, the emission becomes exceedingly strong and the emission region encompasses the whole channel zone.
Resonant nanogratings and periodic metasurfaces express diverse spectral and polarization properties on broadside illumination by incident light. Cooperative resonance interactions may yield shaped spectra for particular applications, in contrast to a multilayer dielectric mirror. Here, we provide guided-mode resonance filters with flat-top spectra suitable for wavelength division multiplexing systems. Applying a single one-dimensional grating layer sandwiched by two waveguides, we theoretically achieve high-efficiency flat-top spectra in the near-infrared region. This result is obtained by inducing simultaneous nearly degenerate resonant modes. The resonance separation under this condition controls the width of the flat-top spectrum. This means we can implement spectral widths ranging from a sub-nanometer to several nanometers applying fundamentally the same device architecture.
A guided-mode resonance mirror (GMRM) consisting of a subwavelength grating integrated in an optical waveguide on a highly reflective substrate was predicted to give interesting characteristics of high reflectance with a steep reflection-phase spectrum. This time, the characteristics were experimentally demonstrated for the first time. A GMRM of 1535 nm resonance wavelength was designed and fabricated for a vertically injected wave from the air with TE polarization. The reflectance was measured to be higher than −1 dB over the wavelength from 1520 to 1560 nm. The reflection phase varied by π for a wavelength change of 10 nm.
We fabricated organic light-emitting field-effect transistors (OLEFETs) characterized by partitioned heterogeneous source and drain contacts along with an aluminum-doped zinc oxide (AZO) layer inserted between an organic layer and a gate insulator. We elaborated such contacts so that each contact was made of a metal(s) suitable for injecting either electrons or holes. We fabricated the devices by choosing two of three kinds of metals (Au, Al, and MgAg) and one of three organic semiconductor materials. In the devices with the Au source and MgAg drain contacts, we observed drain currents at both positive and negative drain voltages. Those currents were predominant at negative drain voltages in the devices with Al drain contacts. The most intense current-injected emissions arose from the vicinity of the electron injection contact edges near channels on the AZO layers. Taking into account the energy level consideration of the materials and the effect of the partitioned contacts, we discussed these electrical and emission properties.
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