Effect of KCl and CsCl on the Electrical Conductivity of Molten LiF–KBr at the Critical Composition

The electrical conductivity was measured from the melting point to 1280 K for molten 0.7 LiF–0.3 KBr (its composition corresponds to the top of the miscibility gap) containing (2.3, 4.4, 6.5, 8.8, and 11.2) mol % KCl or (1.2, 2.5, 5.5, and 10.2) mol % CsCl to establish the influence of this solute on the stability of the two-phase system. These results indicate that the temperature dependences of the conductivity along the saturation lines for all of the mixtures studied herein are similar to one another. Hence, this demonstrates that small additions of KCl and CsCl to the dissolving melt of LiF-KBr do not exert a substantial influence on its type of criticality. In the vicinity of the critical point, the temperature dependence on conductivity differences for melts is investigated and is described by the equation Δκ ≈ (<i>T</i>_c – <i>T</i>)^<i>k</i>, where <i>k</i> is the critical exponent (<i>k</i> = 0.98). The critical temperature changes as a function of the mixture composition and depends on the ion size of the salt added. The critical temperature increases continuously with the addition of CsCl to molten LiF-KBr, whereas it decreases as the fraction as KCl is added. This circumstance must occur during the organization process, as salts accumulate in the dissolving molten mixture, and they prevent the confluence of the phases at a given operating temperature. To interpret the experimental results, the charged hard sphere model for ionic melts in the Debye–Hückel approximation was used with an account of the excluded volume

X‑ray Generated Recombination Exciplexes of Substituted Diphenylacetylenes with Tertiary Amines: A Versatile Experimental Vehicle for Targeted Creation of Deep-Blue Electroluminescent Systems

Customizable and technology-friendly functional materials are one of the mainstays of emerging organic electronics and optoelectronics. We show that recombination exciplexes of simple substituted diphenylacetylenes with tertiary amines can be a convenient source of tunable deep-blue emission with possible applications in organic electroluminescent systems. The optically inaccessible exciplexes were produced via recombination of radiation-generated radical ion pairs in alkane solution, which mimics charge transport and recombination in the active layer of practical organic light-emitting diodes in a simple solution-based experiment. Despite varying and rather poor intrinsic emission properties, diphenylacetylene and its prototypical methoxy (donor) or trifluoromethyl (acceptor) monosubstituted derivatives readily form recombination exciplexes with <i>N</i>,<i>N</i>-dimethylaniline and other tertiary amines that produce emission with maxima ranging from 385 to 435 nm. The position of emission band maximum linearly correlates with readily calculated gas-phase electron affinity of the corresponding diphenylacetylene, which can be used for fast computational prescreening of the candidate molecules, and various substituted diphenylacetylenes can be synthesized via relatively simple and universal cross-coupling reactions of Sonogashira and Castro. Together, the simple solution-based experiment, computationally cheap prescreening method, and universal synthetic strategy may open a very broad and chemically convenient class of compounds to obtain OLEDs and OLED-based multifunctional devices with tunable emission spectrum and high conversion efficiency that has yet not been seriously considered for these purposes

X‑ray Generated Recombination Exciplexes of Substituted Diphenylacetylenes with Tertiary Amines: A Versatile Experimental Vehicle for Targeted Creation of Deep-Blue Electroluminescent Systems

Customizable and technology-friendly functional materials are one of the mainstays of emerging organic electronics and optoelectronics. We show that recombination exciplexes of simple substituted diphenylacetylenes with tertiary amines can be a convenient source of tunable deep-blue emission with possible applications in organic electroluminescent systems. The optically inaccessible exciplexes were produced via recombination of radiation-generated radical ion pairs in alkane solution, which mimics charge transport and recombination in the active layer of practical organic light-emitting diodes in a simple solution-based experiment. Despite varying and rather poor intrinsic emission properties, diphenylacetylene and its prototypical methoxy (donor) or trifluoromethyl (acceptor) monosubstituted derivatives readily form recombination exciplexes with <i>N</i>,<i>N</i>-dimethylaniline and other tertiary amines that produce emission with maxima ranging from 385 to 435 nm. The position of emission band maximum linearly correlates with readily calculated gas-phase electron affinity of the corresponding diphenylacetylene, which can be used for fast computational prescreening of the candidate molecules, and various substituted diphenylacetylenes can be synthesized via relatively simple and universal cross-coupling reactions of Sonogashira and Castro. Together, the simple solution-based experiment, computationally cheap prescreening method, and universal synthetic strategy may open a very broad and chemically convenient class of compounds to obtain OLEDs and OLED-based multifunctional devices with tunable emission spectrum and high conversion efficiency that has yet not been seriously considered for these purposes