Design, Construction and Optical Response Properties of Dye/Superconductor Assemblies

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9631394 McDevitt This research focuses on the design, fabrication and study of dye-superconductor assemblies. These dyesuperconductor systems are sensitive to the influence of light, making cryogenic optical switching processes possible. Initial work has shown that molecular dyes can be used to sensitize superconductor junctions to specific wavelengths of light. Optically sensitive assemblies which display rapid response time, high sensitivity and selective wavelength response characteristics have been prepared. The spectral response behavior of such systems correlate well with the absorbance properties exhibited by the dye layer. Since a large number of dyes with different spectral and photophysical properties can be incorporated into such systems, it is possible to prepare a plethora of structures which are tailored from the molecular level so as to suit a variety of different applications. Depending on the photophysical properties of the dye, systems which foster rapid and direct energy transfer between the dye and the superconductor can be fashioned. Other systems can be prepared which function through the propagation of thermal waves from the dye to the superconductor. Moreover, injection of "hot" (i.e. nonequilibrium) electrons can also be envisioned as an alternative method to induce a measurable electrical response in the superconductor. Interesting issues related to the efficiency of energy and electron transfer phenomena between excited dyes and superconducting interfaces can be explored for the first time with the use of highly oriented thin film structures. Important information related to the chemical compatibility between the molecular dye components and the cuprate compounds can be acquired through an evaluation of the superconductor interfacial properties before and after dye deposition. From the proposed studies, the following information is anticipated: 1.) Reliable methods to construct dye-superconductor assemblies will be identified. 2.) Che mical compatibility of molecular layers and high-Tc superconductors will be explored. This information will be useful not only for the development of the optical devices, but also will contribute to the more rapid development of traditional high-Tc thin film devices. 3.) The initial information related to dye-superconductor energy transfer processes will be obtained. 4.) The efficiencies of thermal wave, hot electron injection and direct dipole coupling energy transfer processes will evaluated. 5.) Systems which incorporate luminescent (fluorescent and phosphorescent), nonluminescent, photoconductive, electrochromic and photochromic dye structures will be evaluated to identify and to explore the various molecule/superconductor communication channels. 6.) This highly interdisciplinary program will not only target the development of a knowledge base in a novel new field of science, but will also serve as an excellent training grounds for future scientists in a strategically important area. %%% A broad program which targets the design, fabrication and characterization of dye/superconductor assemblies is described. Work completed in the Investigator's laboratory has already demonstrated that a number of dye systems can be used in combination with superconductor thin film elements to produce a variety of optically sensitive assemblies that respond selectively to different wavelengths of light. The utilization of the superconductors yield structures where very efficient energy transfer between the light harvesting dye layer and the superconductor occurs. The use of various molecular systems affords the opportunity to prepare a plethora of optical!y sensitive structures that can be tailored from the molecular level for a variety of applications. Studies of the dye/superconductor assemblies will yield useful information related to more effective processing methods that can be used for the more rapid commercialization of high-Tc devices. Moreover, the dye/superconductor platform should provide a convenient means to explore dye/dye and dye/superconductor energy and electron transfer phenomena. The ability of a hybrid superconducting assembly to sense different wavelengths of light in a controllable fashion may have important consequences for future application of superconducting sensors and devices.