Unlocking organic polariton lasers with systematic molecular design

非技术描述：本研究旨在通过将光与材料工程相结合来改变碳基有机半导体的特性，为可调谐低功率激光器到量子信息设备的新技术应用开辟一条道路。这种碳基材料在我们的日常生活中无处不在。例如，它们使植物能够通过光合作用收获光。它们的特点是轻巧、灵活的太阳能电池和高端手机和电视的发光二极管（LED）显示屏。重要的研究是通过改变它们的分子结构来控制它们的性质——发出正确颜色的光或有效地传输电流。然而，也可以用光来调整许多材料的特性，这是这个项目背后的关键概念。当两个镜子被高精度地放置在一起时，它们就像小盒子一样，捕捉光线。如果分子半导体被放置在镜子之间，它们可以与这种光强烈地相互作用，并开始以全新的令人惊讶的方式表现出来，形成被称为“极化子”的新状态。这些极化子可以通过新的物理过程发光——有可能改进LED器件——并且可以通过新的途径进行化学反应。在这项研究中，首席研究员的目标是开发新一代有机半导体激光器的极化子。至关重要的是，该项目使用有机材料的系统控制来开发第一个合理的设计规则，以提高激光器的效率和性能。这种方法为通信、传感和新量子技术的多功能、即插即用有机激光器奠定了基础。除了这些技术影响之外，该项目还开发了一种便携式机械演示，以展示极化激子激光器背后的物理概念。研究小组的目标是在当地社区外展中心进行示范。通过亲身探索集体行为是如何受到微小结构变化的影响的，演示使观众参与到科学方法和物理和化学的交叉思想中，如相干性。技术描述：强光-物质耦合形成激子-极化子在材料工程中具有巨大的前景。当应用于有机半导体时，它提供了一种非合成操纵分子波函数和能量结构的方法。这种方法可以改变基本的行为，如电荷和能量传输，允许分子的功能特性被随意重写。这些效应的范围从重定向化学反应到使玻色-爱因斯坦凝聚物在室温下形成。后者有潜力为低阈值电注入激光器提供一个通用平台。然而，关于极化子本质的关键问题阻碍了它们的合理应用：分子材料的复杂电子结构如何影响极化子的能量格局？可以确定哪些分子杠杆来控制极化子的动力学行为？如何构造器件以最大限度地发挥极化子的独特性质？专注于极化子凝聚，研究小组使用一套超快（fs到ps）时间和角度分辨光谱来揭示导致凝聚的动力学过程的分子基础。这些方法与系统的光学微腔变化相结合，包括对半导体有源层和整体器件结构的关键特性的控制。通过将这些结构中的极化子动力学和凝聚阈值相关联，该项目旨在确定控制极化子凝聚的关键特性，并突出可以优化的结构特征。该研究的最终目标是制定一个路线图，系统地降低有机极化子凝聚阈值，以实现电注入激光的平台。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical description:This research seeks to alter the properties of carbon-based organic semiconductors by combining light with materials engineering to open a route for new technological applications from tunable, low-power lasers to quantum information devices. Such carbon-based materials are ubiquitous in our daily lives. For instance, they enable plants to harvest light through photosynthesis. They feature in lightweight, flexible solar cells and light-emitting diode (LED) displays of top-end phones and televisions. Significant research goes into ways to control their properties – emitting light of the right color or transporting current efficiently – by changing their molecular structure. However, it is also possible to tune many materials properties with light, which is the key concept behind this project. When two mirrors are placed very close together with high precision, they act as tiny boxes, trapping light. If molecular semiconductors are placed between the mirrors, they can strongly interact with this light and begin to behave in entirely new surprising ways, forming new states called ‘polaritons’. These polaritons can emit light through new physical processes – potentially improving LED devices – and can undergo chemical reactions through new pathways. In this research, the principal investigator aims to exploit polaritons for a new generation of organic semiconductor lasers. Crucially, the project uses systematic control of the organic material to develop the first rational design rules to improve laser efficiency and performance. This approach lays the foundation for versatile, ‘plug-and-play’ organic lasers for communications, sensing, and new quantum technologies. Beyond these technological impacts, the project develops a portable mechanical demonstration of the physical concept behind polariton lasers. The research team aims to run the demonstration at local community outreach centers. Through hands-on exploration of how the collective behavior is affected by small structural changes, the demonstration engages the audience in the scientific method and in cross-cutting ideas of physics and chemistry like coherence. Technical description:Strong light-matter coupling to form exciton-polaritons holds immense promise for materials engineering. When applied to organic semiconductors, it offers a way to non-synthetically manipulate the molecular wavefunction and energy structure. This approach can alter fundamental behaviors like charge and energy transport, allowing functional properties of molecules to be rewritten at will. These effects range from redirecting chemical reactions to enabling the formation of Bose-Einstein condensates at room temperature. The latter have the potential to provide a general platform for low-threshold, electrically injected lasers. However, critical questions about the nature of polaritons hold back their rational application: How does the complex electronic structure of molecular materials impact the polariton energy landscape? What molecular levers can be identified to control the dynamical behavior of polaritons? How should devices be structured to maximize unique properties of polaritons? Focusing on polariton condensation, the research team uses a suite of ultrafast (fs to ps) time- and angle-resolved spectroscopies to reveal the molecular basis for the dynamical processes leading to condensation. These methods are combined with systematic optical microcavity variation, including control over critical properties of the semiconductor active layer and the overall device structure. By correlating polariton dynamics and condensation thresholds across these structures, the project aims to identify the crucial properties that govern polariton condensation and highlight the structural features that can be optimized. The ultimate goal of the research is to develop a roadmap to systematically reduce organic polariton condensation thresholds to achieve a platform for electrically injected lasing.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.