Ultra-fast, ultra-small and ultra-dilute: an integrated understanding of conjugated polymers in solution across spatial and temporal scales

共轭聚合物是一类重要的有机(碳基)半导体。它们结合了新的半导体电子特性和简单的从溶液中制造器件。它们使塑料电子领域成为可能，包括柔性照明、显示器、太阳能电池和电子产品。它们的灵活性、电和光的相互转换能力以及简单的制造工艺的结合是非常不同寻常的，使许多应用成为可能。这些材料最有趣的特点之一是它们既是半导体，又是可溶的。这意味着它们可以被溶解成溶液，并通过喷墨打印等简单过程进行沉积，以制造工作的电子和光电子设备(如光源和太阳能电池)。共轭聚合物在溶液中的行为非常复杂，因为每个聚合物都由超小和灵活的原子链组成，因此可以以不同的方式折叠。聚合物的一种特殊形状称为它的构象。聚合物的构象不是静态的，在溶液中可以在超快的时间尺度上变化。材料的性质取决于组成聚合物链的构象，而材料的膜结构强烈地受用于成膜的溶液中聚合物的构象的影响。这项提议的目的是通过开发和应用新的测量技术来实现我们对溶液中共轭聚合物的理解的突破。值得注意的是，现在可以研究单个分子，一次一个，看看它们之间有什么不同。与这些超稀释条件相比，大多数实验只测量平均性质。这些方法之间的差异是巨大的--比如知道人们的平均身高为165厘米与每个人的实际身高之间的差异。我们在世界上首次对溶液中的单一共轭聚合物进行了测量，证明了该方法的可行性。我们现在的目标是通过在非常广泛的时间尺度和长度尺度上研究单个分子来改变我们对溶液中共轭聚合物的理解。此外，我们将研究聚合物之间的相互作用以及它们如何在溶液中形成聚集体，这也是已知的影响聚合物构象和材料性质的因素。这项工作将涉及开发特殊的空间和时间分辨率的测量。通过弥合溶液中的超稀释单分子方法、超快泵浦探测方法和超小超分辨率成像方法之间的差距，该提案将提供一套“首创技术”，将对CP的功能提供前所未有的见解。该提议将首次提供对溶液中CP链的结构异质性和动力学的测量，以及每种构象与其光物理性质之间的直接关联。这些基础知识将为改进共轭聚合物和器件奠定基础，并推动材料科学的广泛应用。

Conjugated polymers are an important class of organic (carbon-based) semiconductor. They combine novel semiconducting electronic properties with simple fabrication of devices from solution. They enable the field of plastic electronics including flexible lighting, displays, solar cells and electronics. Their combination of flexibility, ability to interconvert electricity and light, and simple fabrication is very unusual and enables many applications. One of the most interesting features of these materials is that they are both semiconductors and soluble. This means they can be dissolved to make a solution and deposited by simple processes such as ink jet printing to make working electronic and optoelectronic devices (such as light sources and solar cells). The behaviour of conjugated polymers in solution is very complicated because each polymer consists of a chain of atoms that is ultra-small and flexible, and so can fold in a different way. A particular shape of the polymer is known as its conformation. The conformation of the polymer is not static and can change at ultra-fast timescales in solution. The properties of the material then depend on the conformations of the constituent polymer chains, and the structure of films of the material are strongly influenced by the conformation of the polymers in the solution used to make the film.The aim of this proposal is to achieve a breakthrough in our understanding of conjugated polymers in solution by developing and applying new measurement techniques. Remarkably it is now possible to study individual molecules, one at a time to see how they are different from each other. In contrast to these ultra-dilute conditions, most experiments just measure average properties. The difference between these approaches is huge - like the difference between knowing the average height of people is 165 cm and the actual height of every person. We have made the first measurements in the world of single conjugated polymers in solution, demonstrating the feasibility of the approach. We now aim to transform our understanding of conjugated polymers in solution by studying individual molecules over a very wide range of timescales and length scales. In addition, we will study the interactions between polymers and how they form aggregates in solution, which are also known to impact the conformation of the polymer and the properties of the material.This work will involve developing measurements of exceptional spatial and temporal resolution. By bridging the gap between ultra-dilute single-molecule methods in solution, ultra-fast pump-probe and ultra-small super-resolution imaging, the proposal will deliver a set of 'first of its kind techniques' that will give unprecedented insights into CP function. The proposal will provide, for the first time, a measurement of the structural heterogeneity and dynamics of CP chains in solution and a direct correlation between each conformation and its photophysical properties. This basic knowledge will lay the foundations for improved conjugated polymers and devices and empower a broad range of applications across material sciences.