Structure-Property-Performance Relationships for Organic Bulk Heterojunction Solar Cells

有机半导体结合了传统上与无机材料相关的半导体特性和塑料的更令人满意的特性，如低成本、灵活性和易于加工和构图。此外，这些材料的有机合成允许在调节它们的电子和光学性质方面有很大的灵活性。通过结合这些性质，有机半导体，如共轭聚合物和小分子，已经被证明是包括光伏太阳能电池在内的广泛的光学和电子器件的有源层。有机太阳能电池的主要设计是基于体相异质结，其中有机混合物包括电子供给组分(通常是共轭聚合物)和电子接受组分(如富勒烯衍生物或共轭聚合物)，它们溶解在同一溶剂中，然后从溶液中旋转涂覆，形成一层薄膜，夹在两个不同的电极之间。材料和器件制造工艺的最新发展正在导致这些器件性能的快速改进。例如，据报道，溶液处理的有机太阳能电池的太阳能转换效率高达5-6%。尽管它们的器件性能有了显著的改善，但在更充分地了解、量化和预测有机体异质结太阳能电池的行为方面，仍然存在一些科学挑战。特别是，器件性能对有机共混物薄膜形态的依赖以及影响共混物溶液中特定薄膜结构发展的因素仍然知之甚少。为了了解有机共混薄膜和器件之间的相互作用，重要的是确定有机材料的结构-性质关系及其对器件性能的影响。我们在伦敦帝国理工学院的工作旨在为这个问题提供关键的基础和技术见解。我们的目标是阐明有机体异质结太阳能电池的结构-性能-性能关系。我们将通过结合应用扫描探针显微镜技术和光学和电学技术来识别有机纳米结构和界面的化学、物理、光学和电学性质，从而阐明这些有机纳米结构和界面对器件性能的作用。我们的愿景是，只有通过测量这些性质获得的完全互补的信息才能为研究有机纳米结构和界面提供必要的强大工具，从而进一步发展有机体异质结太阳能电池。

Organic semiconductors combine the semiconductor properties traditionally associated with inorganic materials with the more desirable properties of plastics such as low cost, flexibility and ease of processing and patterning. Moreover, the organic syntheses of these materials allow for great flexibility in the tuning of their electronic and optical properties. By combining these properties, organic semiconductors such as conjugated polymers and small molecules have been demonstrated as the active layer in a wide range of optical and electronic devices including photovoltaic solar cells. The leading design of organic solar cells is based on the bulk heterojunction , in which organic blends comprising an electron donating component (usually a conjugated polymer) and an electron accepting component (such as a fullerene derivative or a conjugated polymer) that are dissolved in the same solvent and then spin-coated from the solution to form a thin film, sandwiched between two different electrodes. Recent developments in materials and device fabrication processes are leading to rapid improvements in performance of these devices. For example, solar conversion efficiencies up to 5-6 % were reported for solution-processed organic solar cells. Despite their significantly improved device performance, a number of scientific challenges remain to more fully understand, quantify, and predict the behaviour of the organic bulk heterojunction solar cells. In particular, the dependence of device performance on the thin film morphology of organic blends and the factors affecting the development of specific thin film structures from blend solutions are still poorly understood. To understand the interplay between the organic blend thin films and devices, it is therefore important to identify the structure-property relationship of the organic materials and its effects on device performance.Our work at Imperial College London seeks to provide key fundamental and technological insights into this issue. We aim to clarify the structure-property-performance relationships of organic bulk heterojunction solar cells. We will achieve this aim through a combined application of scanning probe microscopic techniques and optical and electrical techniques to identify the nature of organic nanostructures and interfaces in terms of their chemical, physical, optical, and electrical properties, and thus to clarify the role of these organic nanostructures and interfaces on device performance. It is our vision that only the fully complementary information obtained by measurements of these properties will be able to provide the necessary powerful tool to study organic nanostructures and interfaces and thus to further develop organic bulk heterojunction solar cells.