Bright red emission with high color purity from Eu(iii) complexes with π-conjugated polycyclic aromatic ligands and their sensing applications

In this review, we summarize the research progress on π-conjugated Eu(iii) luminophores exhibiting bright emission and their physical sensing applications.

Simultaneous High Dynamic Range Algorithm, Testing, and Instrument Simulation

Within an imaging instrument’s field of view, there may be many observational targets of interest. Similarly, within a spectrograph’s bandpass, there may be many emission lines of interest. The brightness of these targets and lines can be orders of magnitude different, which poses a challenge to instrument and mission design. A single exposure can saturate the bright emission and/or have a low signal-to-noise ratio (S/N) for faint emission. Traditional high dynamic range (HDR) techniques solve this problem by either combining multiple sequential exposures of varied duration or splitting the light to different sensors. These methods, however, can result in the loss of science capability, reduced observational efficiency, or increased complexity and cost. The simultaneous HDR method described in this paper avoids these issues by utilizing a special type of detector whose rows can be read independently to define zones that are then composited, resulting in areas with short or long exposure measured simultaneously. We demonstrate this technique for the Sun, which is bright on disk and faint off disk. We emulated these conditions in the lab to validate the method. We built an instrument simulator to demonstrate the method for a realistic solar imager and input. We then calculated S/Ns, finding a value of 45 for a faint coronal mass ejection and 200 for a bright one, both at 3.5  ⊙ N —meeting or far exceeding the international standard for digital photography that defines an S/N of 10 as acceptable and 40 as excellent. Future missions should consider this type of hardware and technique in their trade studies for instrument design.

Relativistic Configuration-Interaction and Perturbation Theory Calculations of the Sn XV Emission Spectrum

Recently, there has been increased interest in developing advanced bright sources for lithography. Sn ions are particularly promising due to their bright emission spectrum in the required wavelength range. Cowan’s code has been used to model the emission; however, it has adjustable parameters, which limit its predictive power, and it has limited relativistic treatment. Here, we present calculations based on ab initio relativistic configuration-interaction many-body perturbation theory (CI-MBPT), with relativistic corrections included at the Dirac-Fock level and core-polarization effects with the second-order MBPT. As a proof of principle that the theory is generally applicable to other Sn ions with proper development, we focused on one ion where direct comparison with experimental observations is possible. The theory can also be used for ions of other elements to predict emissions for optimization of plasma-based bright sources.

The Deformation Behavior and Bending Emissions of ZnO Microwire Affected by Deformation-Induced Defects and Thermal Tunneling Effect

The realization of electrically pumped emitters at micro and nanoscale, especially with flexibility or special shapes is still a goal for prospective fundamental research and application. Herein, zinc oxide (ZnO) microwires were produced to investigate the luminescent properties affected by stress. To exploit the initial stress, room temperature in situ elastic bending stress was applied on the microwires by squeezing between the two approaching electrodes. A novel unrecoverable deformation phenomenon was observed by applying a large enough voltage, resulting in the formation of additional defects at bent regions. The electrical characteristics of the microwire changed with the applied bending deformation due to the introduction of defects by stress. When the injection current exceeded certain values, bright emission was observed at bent regions, ZnO microwires showed illumination at the bent region priority to straight region. The bent emission can be attributed to the effect of thermal tunneling electroluminescence appeared primarily at bent regions. The physical mechanism of the observed thermoluminescence phenomena was analyzed using theoretical simulations. The realization of electrically induced deformation and the related bending emissions in single microwires shows the possibility to fabricate special-shaped light sources and offer a method to develop photoelectronic devices.

How Do Molecular Motions Affect Structures and Properties at Molecule and Aggregate Levels?

<p>Experimental and theoretical analysis demonstrated that the active intramolecular motions in the excited state of all molecules at single molecule level imparted them with more twisted structural conformations and weak emission. However, owing to the restriction of intramolecular motions in the nano/macro aggregate state, all the molecules assumed less twisted conformations with bright emission. Synergic strong and weak intermolecular interactions allowed their crystals to undergo reversible deformation, which effectively solved the problem of the brittles of organic crystals, meanwhile imparted them with excellent elastic performance. </p>

How Do Molecular Motions Affect Structures and Properties at Molecule and Aggregate Levels?

<p>Experimental and theoretical analysis demonstrated that the active intramolecular motions in the excited state of all molecules at single molecule level imparted them with more twisted structural conformations and weak emission. However, owing to the restriction of intramolecular motions in the nano/macro aggregate state, all the molecules assumed less twisted conformations with bright emission. Synergic strong and weak intermolecular interactions allowed their crystals to undergo reversible deformation, which effectively solved the problem of the brittles of organic crystals, meanwhile imparted them with excellent elastic performance. </p>

Efficient Interfacial Upconversion Enabling Bright Emission with Extremely Low Driving Voltage in Organic Light-Emitting Diodes

Reducing operating voltage is the remaining frontier for organic light-emitting diodes (OLEDs) because their quantum efficiency (QE) of electroluminescence has been already maximized. Herein, we report an efficient OLED in which a blight emission equivalent to a luminance of a display is achieved by only a 1.5 V battery. The OLED is based on upconversion (UC) emission utilizing triplet-triplet annihilation occurring near donor/acceptor (D/A) interface. We found that a character of a charge transfer state that is key intermediate for the UC emission could be controlled by D/A interfacial interaction. As a result, parasitic loss processes for UC were greatly suppressed from over 90% to about 10%, and two order of magnitude higher QE than the previous UC-OLED was achieved. Our result demonstrated that the efficient UC could be realized by the management of the energy transfer steps at the D/A interface and utilizing UC emission can be one of the possible candidate for efficient OLED with extremely low driving voltage.