Tailoring exciton-photon interactions in organic semiconductor microcavities: From resonance-controlled photophysics to spontaneous coherence

定制有机半导体微腔中的激子-光子相互作用：从共振控制光物理到自发相干

• 批准号: RGPIN-2014-04530
• 负责人: Silva, Carlos
• 金额: $ 3.06万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=566579
• 关键词: Tailoring; exciton; photon; interactions; organic

If intense light irradiates solids, an exotic phase of matter called a Bose-Einstein condensate (BEC) is possible. By interacting strongly with materials, light couples with electrons to make 'half-light, half-electron' quasiparticles, termed exciton-polaritons, many of which may occupy the same quantum-mechanical state, so they all move as one, akin to a large ensemble of pairs of figure skaters, all performing in exquisite choreography when the spotlight is upon them. Individual particles lose their identity, acting cooperatively as a 'quantum liquid' over the entire solid when the laser shines on it. Such macroscopic spontaneous coherence (the collective quantum behaviour polaritons, much like the large number of figure skaters) of is at the origin of many important but poorly understood condensed-matter phenomena such as superfluidity. These states have only been observed in very specific solids called semiconductor quantum wells – built by atoms arranged in a crystal, in which electrons are confined to move in two dimensions, and at very low temperatures (~20 K, or -253 °C). I will address the following question: can we find such condensates at room temperature in solids made with molecules? This is a big question because it addresses the physics of these states in materials beyond 'simple' solids, built with organic molecules like those that surround us and are in us, in a temperature environment familiar to us. Understanding this fundamental behaviour will bring new breakthroughs in quantum mechanics by generalising the physics of formation and dissipation of this new state of matter. This may lead to new coherent light sources that consume less power than conventional lasers, and to devices that may be used in quantum computers. Molecules are configurationally 'soft and fluffy', resulting in structural disorder. Electronic interactions between molecules are therefore complex, which can be an important cause of coherence dissipation, potentially hindering condensation. Nonetheless, organic materials are ideal candidates for BEC because they absorb light very strongly, rendering the strength of the coupling between photons (light) and electrons well over an order of magnitude larger than in quantum wells, and can be stronger than energetic disorder in good optical devices. Furthermore, in organic semiconductors it is theoretically possible to form quantum condensates in these materials at room temperature, which is not generally possible with inorganic quantum wells with over an order of magnitude lower exciton binding energies. I will fabricate new devices based on plastics, which will permit the study of these fundamental physics with intricate detail because it will be possible to more easily incorporate molecular materials in them. I will study a range of materials that conduct electricity and may be used in optoelectronic devices, ranging from crystals composed of molecules to conducting plastics. I underline the potential for transformative impact of the proposed programme of work. We will use new fabrication protocols to make devices, and then study them with sophisticated experimental techniques producing short laser pulses (shorter than a millionth of a millionth of a second) to study polariton condensation processes in real time. The impact of my work will be to develop a rigorous framework to understand and control how light interacts with these materials, and real-life applications such as lasers can emerge in the long term. This grant will enable big-picture understanding of photophysics of plastic semiconductors, connecting concepts from classical polymer science, condensed-matter physics, and chemical physics.

如果强烈的光照射固体，则可以使用称为Bose-Einstein冷凝物（BEC）的物质相。通过与材料进行牢固的互动，带有电子的轻伴侣使“半灯，半电子”的准粒子称为令人兴奋的二极之异，其中许多可能占据相同的量子力学状态，因此它们都像一个一样，类似于一个类似于一对大型滑冰运动员，在他们的分布层次中都表现出了众多的培训，当时它们都在其上表现出来。各个颗粒失去了身份，当激光闪耀时，在整个固体上合作起作用。这种宏观的赞助（类似于大量的花样溜冰者的集体量子行为极化子）的起源是许多重要但知之甚少的凝结现象，例如超流体。这些状态仅在非常具体的固体中观察到，称为半导体量子井 - 由排列在晶体中的原子建造，其中电子被局限于二维和温度非常低的（〜20 K或-253°C）。我将解决以下问题：我们可以在用分子制成的固体中找到这种冷凝水吗？这是一个很大的问题，因为它在“简单”固体之外的材料中解决了这些状态的物理，并用像我们周围的人一样，在我们熟悉的温度环境中建立的有机分子。了解这种基本行为将通过概括形成和耗散这种新物质的物理学来带来新的量子力学突破。这可能会导致新的连贯的光源比常规激光器所消耗的功率少，并导致可以在量子计算机中使用的设备。分子在构型上是“柔软和蓬松的”，导致结构障碍。因此，分子之间的电子相互作用是复杂的，这可能是连贯性耗散的重要原因，可能会阻碍凝结。但是，有机材料是BEC的理想候选者，因为它们非常强烈地吸收光线，从而使照片（光线）和电子之间的耦合强度远远超过量子井中的数量级，并且在良好的光学设备中可能比能量疾病更强。此外，在有机半导体中，理论上有可能在室温下在这些材料中形成量子冷凝物，这通常是没有有机量子井，而令人兴奋的结合能较低的无机量子井。我将根据塑料制造新的设备，这将允许对这些基本物理学进行复杂的细节进行研究，因为可以更轻松地将它们纳入其中的分子材料。我将研究一系列传导电力的材料，可用于光电设备，从由分子组成的晶体到传导塑料。我强调了拟议的工作计划对变革性影响的潜力。我们将使用新的制造协议来制造设备，然后使用复杂的实验技术研究它们，从而产生短激光脉冲（短于一百万秒），以实时研究偏振仪的冷凝过程。我的工作的影响将是开发一个严格的框架，以了解和控制光线与这些材料的相互作用，从长远来看，例如激光器（例如激光器）可以出现。这项赠款将使对塑料半导体的光体物理学，经典聚合物科学，凝结物理物理学和化学物理学的概念相连。