Molecular Photonic Breadboards

如果我们要在地球上可持续地生活，就需要新的制造方法。在电子工业中，人们对使用有机材料制造设备的可能性有着巨大的兴趣：它们可以用地球上丰富的资源以可持续的方式制造，其能源成本通常比生产同等无机材料的能源成本要低得多。以有机成分为基础的电子设备现在在大街上随处可见。例如，有机发光二极管用于生产一些高端电视机和智能手机（如iPhone X）中使用的显示器。然而，一个根本的问题阻碍了有机材料在电子器件中的全部潜力的实现。当光被分子半导体吸收时，它会产生激子——一对相反的电荷——通过器件携带激发。然而，有机材料中的激子重组和相互抵消的速度非常快——它们只能在材料中移动很短的距离。这一基本障碍限制了有机材料在消费电子产品和许多其他技术领域的应用，如量子通信、光催化和传感器技术。我们提出了一种全新的方法来解决这个问题，该方法基于将受光合作用机制启发的分子设计与纳米结构材料相结合，产生令人惊讶和有趣的量子光学效应，将光和物质的性质混合在一起。在面包板上，螺纹支架将光学元件相互相对固定，这样光线就可以直接通过光学系统。这个建议也旨在设计面包板，但是是一种非常不同的类型。最小的组成部分将是单个的发色团（光吸收分子），由称为天线复合物的最小构建块在空间中固定排列，其结构受到参与光合作用的蛋白质的启发。天线复合体是利用合成生物学和化学从零开始设计和制造的，因此能量的传递可以通过对天线结构进行编程来控制。代替使用螺纹安装，我们将通过附着在纳米光刻在固体表面形成的反应化学基团来组织这些组件。在这些激子薄膜中，我们将制定有效远程输运的设计规则。在传统的面包板中，光在组件之间以直线传播。然而，我们将利用强光-物质耦合现象来实现完全不同类型的能量转移。在强耦合中，局部等离子体共振（一种局限于纳米粒子表面的光模式）与分子激子混合，产生一种结合了光和物质特性的新态，称为多激子。我们将创建多激子复合物，在每个复合物中，多达1000个发色团的阵列与等离子体模式强耦合。在这些多激子复合物中，耦合是集体的——所有的发色团同时耦合到等离子体，因此能量转移的规则被完全重写。能量不再通过一系列线性跳跃步骤传递（就像在有机半导体中一样），而是在整个结构中瞬间离域——比传统有机半导体可能的远许多个数量级。通过从头开始设计这些复激子复合物，我们的目标是创造出全新的特性。所得材料从单个发色团到宏观结构都是完全可编程的。通过将生物灵感设计与强光-物质耦合相结合，我们将创造出许多新型的功能结构，包括新型医疗传感器、“多激子电路”和适用于许多应用的量子光学薄膜，采用低成本、环保的方法。

New manufacturing methods are required if we are to live sustainably on the earth. In the electronics industry there is enormous interest in the possibility of manufacturing devices using organic materials: they can be manufactured sustainably from earth-abundant resources at energy costs that are typically significantly less than those associated with the production of equivalent inorganic materials. Electronic devices based on organic components are now readily available in the high street. For example, organic light-emitting diodes are used to produce the displays used in some high-end TV sets and in smartphones (e.g. iPhone X). However, a fundamental problem prevents the realisation of the full potential of organic materials in electronic devices. When light is absorbed by molecular semiconductors, it causes the creation of excitons - pairs of opposite charges - that carry excitation through the device. However, the excitons in organic materials recombine and cancel themselves out extremely rapidly - they can only move short distances through the material. This fundamental obstacle limits the application of organic materials in consumer electronics and also in many other areas of technology - in quantum communications, photocatalysis and sensor technologies.We propose an entirely new approach to solving this problem that is based on combining molecular designs inspired by photosynthetic mechanisms with nanostructured materials to produce surprising and intriguing quantum optical effects that mix the properties of light and matter.On breadboards, threaded mounts hold optical components relative to one another so that rays of light can be directed through an optical system. This proposal also aims to design breadboards, but of a very different kind. The smallest components will be single chromophores (light absorbing molecules), held at fixed arrangements in space by minimal building blocks called antenna complexes, whose structures are inspired by those of proteins involved in photosynthesis. Antenna complexes are designed and made from scratch using synthetic biology and chemistry so that transfer of energy can be controlled by programming the antenna structure. Instead of using threaded mounts, we will organise these components by attachment to reactive chemical groups formed on solid surfaces by nanolithography. In these excitonic films, we will develop design rules for efficient long-range transport.In conventional breadboards, light travels in straight lines between components. However, we will use the phenomenon of strong light-matter coupling to achieve entirely different types of energy transfer. In strong coupling, a localised plasmon resonance (an light mode confined to the surface of a nanoparticle) is hybridised with molecular excitons to create new states called plexcitons that combine the properties of light and matter. We will create plexcitonic complexes, in each of which an array of as many as a thousand chromophores is strongly coupled to a plasmon mode. In these plexcitonic complexes, the coupling is collective - all the chromophores couple to the plasmon simultaneously, and so the rules of energy transfer are completely re-written. Energy is no longer transferred via a series of linear hopping steps (as it is in organic semiconductors), but is delocalised instantaneously across the entire structure - many orders of magnitude further than is possible in conventional organic semiconductors. By designing these plexcitonic complexes from scratch we aim to create entirely new properties. The resulting materials are fully programmable from the scale of single chromophores to macroscopic structures.By combining biologically-inspired design with strong light-matter coupling we will create many new kinds of functional structures, including new medical sensors, 'plexcitonic circuits', and quantum optical films suitable for many applications, using low-cost, environmentally benign methods.