Apertureless scanning near-field optical studies of energy and charge transfer in molecular materials for opto-electronic devices.

发展高效电子器件是分子电子学的主要目标。为了实现这一点，我们需要充分了解能量是如何从一个分子传递到另一个分子的。理论上，对于两个小分子来说，这是一个很容易理解的问题。然而，在由半导体聚合物共混物制成的电子器件中，能量转移发生在不同聚合物结构域之间的边界上。在这些边界上，发生在几个纳米尺度上的许多过程可以在能量转移过程的效率中发挥重要作用。为了研究这些工艺对器件效率的影响，我的目标是开发一种无孔扫描近场显微镜(A-SNOM)。这台显微镜将使我能够以足够高的分辨率研究各种材料的光学性质，以足够高的分辨率分辨单个分子。使用A-SNOM，我将研究基于共轭聚合物的各种光电系统。首先，我将研究共轭聚合物的混合物。这些聚合物可以与其他聚合物或小分子混合，用作发光二极管或光伏器件的活性材料。这将有助于更好地了解这些体系中的能量传递，并可用于提高基于共轭聚合物共混的器件的效率。我将研究的第二组材料将包括从特殊细菌中提取的捕光复合体(LHC)与共轭聚合物结合，以便聚合物在保护细菌的同时促进能量从聚合物转移到细菌。这将是将细菌化合物用于分子电子学的首批纳米级研究之一。最后，A-SNOM将用于研究少量相互作用的分子。A-SNOM的高分辨率将使我能够成像作为(能量)供体或受体分子的单分子的光学性质。这可以用来提高我们对这些分子之间的电子相互作用的理解。研究单个分子(或两个相互作用的分子)将会引起理论家的兴趣，并将有助于揭示真实设备中发生的过程。使用其他传统的测量技术是不可能的。最后，还有可能直接将分子的形态与其能量传递能力联系起来。A-SNOM将使我能够同时测量分子的形态和光学性质。这些研究的结果将与一个光伏设备模型结合使用，这将使我能够了解限制设备性能的基本工艺。该装置将由交替的低和高Bang-Gap聚合物图案条组成。将有可能纳入在上述研究期间获得的结果，以提高设备效率。

The development of highly efficient electronic devices is a major goal of molecular electronics. To achieve this we need to fully understand how energy is passed from one molecule to another. Theoretically this is a simple problem to understand for two small molecules. However, in electronic devices made from blends of semi-conducting polymers energy transfer occurs at the boundaries between different polymer domains. At these boundaries many processes that occur on length scales of several nanometres can play an important role in the efficiency of the energy transfer process. To study the effect these processes have on device efficiency, I aim to develop an apertureless scanning near field microscope (A-SNOM). This microscope will allow me to study the optical properties of a variety of materials at a resolution high enough to resolve individual molecules.Using the A-SNOM I will study a variety of opto-electronic systems based on conjugated polymers. Firstly I will study blends of conjugated polymers. These polymers can be blended with other polymers or small molecules and be used as the active material in light emitting diodes or photo-voltaic devices. This will lead to a greater understanding of energy transfer in these systems and can be used to improve the efficiency of devices based on blends of conjugated polymers. The second group materials I will study will consist of light harvesting complexes (LHC) derived from specialised bacteria combined with conjugated polymers, in order that the polymers protect the bacteria while facilitating energy transfer from the polymer to the bacteria. This will represent one of the first nanoscale studies of the use of bacterial compounds in molecular electronics. Finally the A-SNOM will be used to study small numbers of interacting molecules. The high resolution of A-SNOM will allow me to image the optical properties of single molecules acting as either (energy) donor or acceptor molecules. This can be used to improve our understanding in the electronic interactions between these molecules. Studying single molecules (or two interacting molecules) will be of interest to theoreticians and will shed light on processes that occur in real devices. This is not possible using other conventional measurement techniques. Finally it will also be possible to directly correlate a molecules morphology with its energy transfer ability. The A-SNOM will allow me to make simultaneous measurements of a molecules morphology and optical properties. The results from these studies will be used in conjunction with a model photovoltaic device which will permit me to understand fundamental process which limit device performance. The device will consist of patterned strips of alternating low and high bang-gap polymers. It will be possible to incorporate results obtained during the studies outlined above to increase device efficiency.