Photophysics of Mid-Infrared Colloidal Quantum Dots

该项目由材料研究部(DMR)的电子与光子材料(EPM)和凝聚态物质物理(CMP)计划共同资助。技术：该项目是关于胶体量子点的合成、光谱和动力学研究，代表了在3至10微米的中红外光谱范围内评估胶体点光物理的综合努力。这项研究使用量子限制来创造中红外电子跃迁。材料是半金属HgTe和宽禁带半导体Cd(Te，Se，S)。HgTe成为小尺寸可调的中红外禁带半导体，而Cd(Te，Se，S)胶体点在这个中红外光谱范围内有很强的带内跃迁。利用皮秒中红外时间分辨激光光谱研究了禁闭对能量弛豫、热性质、低激发能级和高激发能级的影响。胶体点上的配体引入了红外电子激发与分子振动的耦合。开发工艺是为了消除或减少有机配体的影响，这将允许较慢的声子弛豫和俄歇过程，促进光检测和激光。非技术：该项目解决材料研究的一个主题领域的基础研究问题，具有潜在的技术影响。这项研究的成功将扩大我们对光谱范围从3到10微米的胶体量子点红外特性的基本理解。这些量子点的潜在应用包括红外光电探测器和激光。红外检测在热成像和分子检测中具有重要的应用价值。红外激光在大气污染物的光谱分析和电信方面很有用。在这个项目中，研究生和本科生在一个结合了材料科学、物理和化学的跨学科环境中接受培训。

This project is co-funded by the Electronic and Photonic Materials (EPM) and Condensed Matter Physics (CMP) Programs in the Division of Materials Research (DMR).Technical: This project is on synthesis, spectroscopy and dynamic studies of colloidal quantum dots and represents a comprehensive effort to evaluate the photophysics of colloidal dots in the mid-infrared spectral range from 3 to 10 micrometers. The research uses quantum confinement to create mid-infrared electronic transitions. The materials are the semimetal HgTe and the wide band gap semiconductors Cd(Te, Se, S). HgTe becomes a tunable mid-infrared gap semiconductor at small sizes while the Cd(Te, Se, S) colloidal dots have strong intraband transitions in this mid-infrared spectral range. The effects of confinement on energy relaxation, thermal properties, and low- and high-excitation levels are investigated by using picosecond mid-infrared time-resolved laser spectroscopy. Ligands on the colloidal dots introduce coupling of the infrared electronic excitations to molecular vibrations. Processing is developed to eliminate or reduce the effect of organic ligands, which will allow slower phonon relaxation and Auger processes, facilitating photodetection and lasing.Non-Technical: The project addresses basic research issues in a topical area of materials research, with potential technological impacts. Success of the research will expand our fundamental understanding of the infrared properties of colloidal quantum dots in a spectral range from 3 to 10 micrometers. Potential applications of these quantum dots include infrared photodetector and lasers. Infrared detection is useful for thermal imaging and molecular detection. Infrared lasers are useful for spectral analysis of atmospheric contaminants and telecommunications. In this project, graduate and undergraduate students are trained in an interdisciplinary environment that combines materials science, physics, and chemistry.