NER: Molecular Self-Assembly for Dye Sensitized Photonic Nanodevices

染料敏化是提高高禁带半导体光谱响应的重要技术，高禁带半导体在光电化学电池中更稳定。 然而，这些器件具有低的量子效率和差的稳定性。 最严重的问题之一是浓度猝灭，其中吸收的光子能量由于染料分子的分离而作为热能耗散。抑制浓度猝灭的唯一方法是设计一种将染料分子分散在表面上的方法，最大限度地减少聚集体的形成。 在该提案中，研究人员将开发必要的设备和材料处理技术，以防止分子自组装方法分离染料分子。 该项目的初步研究将证明该技术的可行性。 研究人员将采用自组装技术将染料分子插入半导体表面生长的纳米多孔材料的几个单层中。 将研究两种类型的原型装置。首先，将通过在表面上沉积导电且透明的金属氧化物膜来制造光电检测器，其次，将通过将染料涂覆的电极浸入电化学电池中来制备光电化学电池。 对器件的结构、表面特性、光电流、量子效率和光学特性进行了测量和模拟。 预计这些类型的自组装方法可以广泛用于许多其他应用中，例如分子器件、纳米级生物系统和纳米电子学。 该项目的更广泛的影响包括：（一）本科生和研究生的研究，（二）通过提供研讨会参与高中推广计划，以及（三）在学院建立纳米技术课程的基础。 两名本科生和两名全日制研究生将参与实验工作。将尽一切努力让来自不同背景的学生参与纳米技术。

Dye sensitization is an important technique to increase the spectral photoresponse in high bandgap semiconductors, which are more stable in photo-electrochemical cells. However, these devices have low quantum efficiencies and poor stability. One of the most serious problems is the concentration quenching in which absorbed photon energy is dissipated as heat energy due to the segregation of dye molecules. The only way to suppress concentration quenching is to devise a method of dispersing dye molecules on the surface, minimizing the formation of aggregates. Within this proposal, the investigators will develop devices and material processing technologies necessary to prevent segregation of dye molecules by the molecular self-assembly method. The preliminary investigations in this project will demonstrate the feasibility of this technology. The investigators will employ the self-assembling techniques to insert dye molecules into a few monolayers of nanoporous material grown on the semiconductor surface. Two types of prototype devices will be investigated. First, a photodetector will be fabricated by depositing a conductive and transparent metal oxide film on the surface and second, a photo-electrochemical cell will be prepared by immersing the dye-coated electrode in an electrochemical cell. The structure, surface properties, photocurrent, quantum efficiency and optical properties of the devices will be measured and simulated. It is anticipated that these types of self-assembly methods can be widely used in many other applications, such as in molecular devices, nanoscale biosystems, and nanoelectronics. The broader impact of this project includes (i) undergraduate and graduate research, (ii) participation in a high school outreach program by delivering a seminar, and (iii) building the foundation for a nanotechnology course in the college. Two undergraduate students and two full time graduate students will be involved in carrying out the experimental work. Every effort will be made to involve students from diverse background in nanotechnology.