Stability of Organic Solar Cells based on Non-Fullerene Acceptors

有机和其他类型的溶液处理太阳能电池是传统硅基光伏（PV）的非常有前途的替代品，作为一种轻质，灵活，一次性和真正的建筑集成光伏技术，具有非常快的能源回报。然而，富勒烯有限的稳定性已被广泛认为是其商业化的共同瓶颈，暴露于各种环境因素（如光、热、氧、湿度）会导致其性能迅速丧失，其原因通常仍不清楚。富勒烯在过去的二十年中被广泛用作有机太阳能电池（OSC）中的电子受体和传输材料。直到最近3-4年，非富勒烯受体材料才作为富勒烯的更高效、更低成本、更通用的替代品而成为OSC开发的前沿，无富勒烯OSC的性能已经显着超过富勒烯基OSC。然而，迄今为止，大多数研究工作仅致力于进一步优化其效率，在对其稳定性和降解机制的理解方面存在明显差距，这是其商业化的另一个关键考虑因素。该提案旨在解决稳定的无富勒烯OSC开发中三个非常重要但基本上未回答的问题：1-导致无富勒烯的OSC降解的机制是什么; 2-我们能否全面和定量地理解这些降解机制; 3-是什么控制着这些降解机制，以及如何解决它们？为了回答这些问题，该提案将开发一种新的研究方法来研究OSC降解，这是以前没有建立的。通过执行时间分辨和相互关联的光学，结构和功能分析的PV薄膜和器件在本地控制的环境中退化，这种方法能够捕获的基本过程的实时信息，导致器件性能损失的退化过程中，从而建立一个定量的退化机制和所产生的OSC退化行为之间的关系。具体而言，将记录并进一步分析几个先进的性能决定器械参数的演变（即时间分辨）以及同一降解过程中的化学和结构变化（即相互关联），以重建OSC降解行为。该项目只研究不含富勒烯的OSC，但新方法可普遍应用于研究其他类型的太阳能电池，如聚合物：富勒烯，量子点，染料敏化和钙钛矿太阳能电池。该项目的核心重点是定量分析无富勒烯OSC的主要降解机制对其材料和器件设计的影响。PI已经领导了定量研究富勒烯降解及其对OSC稳定性影响的研究工作，这为本文提出的新研究方法的发展奠定了基础。基于所获得的定量知识，该提案还旨在开发全面的材料和器件设计规则，能够指导无富勒烯OSC稳定性的系统优化。该提案将建立在卡迪夫大学在能源材料和设备方面的现有研究专业知识和设施的基础上，并与斯旺西大学和伦敦帝国理工学院密切合作。该项目将与1）Eight 19有限公司合作进行，一家专门从事OSC产品商业化的英国中小企业; 2）NSG集团，一家总部位于英国的世界领先的玻璃和玻璃制品公司（例如玻璃基光伏产品）; 3）Armor集团，一家总部位于法国的专门从事印刷和涂层技术的公司。

Organic and other types of solution-processed solar cells are a highly promising alternative to conventional silicon-based photovoltaics (PV) as a lightweight, flexible, disposable and truly building-integrated PV technology with extremely quick energy payback. However, their limited stability has now been widely recognised as a common bottleneck for their commercialisation, with exposure to various environmental factors (e.g. light, heat, oxygen, humidity) leading to rapid losses of their performance, the origin of which often remains widely unclear.Fullerenes have been ubiquitously used as an electron acceptor and transport material in organic solar cells (OSCs) in the past two decades. Only until the last 3-4 years, non-fullerene acceptor materials have been brought to the forefront of the development of OSCs as a more efficient, lower-cost and more versatile alternative to fullerenes, with the performance of fullerene-free OSCs already significantly exceeding that of fullerenes-based OSCs. Nevertheless, the majority of research efforts to date have only been dedicated to further optimising their efficiency, leaving a clear gap in the understanding of their stability and degradation mechanisms, another key consideration for their commercialisation.This proposal is designed to address three very important yet largely unanswered questions in the development of stable fullerene-free OSCs: 1-What are the mechanisms causing the degradation of fullerene-free OSCs; 2-Can we understand these degradation mechanisms both comprehensively and quantitatively; and 3-What controls these degradation mechanisms and how to address them? To answer these questions, this proposal will develop a new research methodology to study OSC degradation, which has not been established previously. By performing time-resolved and inter-correlated optical, structural and functional analysis of PV films and devices degraded in a locally-controlled environment, this methodology is capable of capturing the real-time information of the fundamental processes leading to device performance losses during the degradation process, thereby establishing a quantitative relationship between the degradation mechanisms and the resulting OSC degradation behaviour. Specifically, the evolution (i.e. time-resolved) of several advanced, performance-determining device parameters, as well as that of chemical and structural changes during the same degradation process (i.e. inter-correlated), will be recorded and further analysed in order to reconstruct the OSC degradation behaviour. Only fullerene-free OSCs will be studied in this project, but the new methodology can be universally applied to study other types of solar cells, such as polymer:fullerene, quantum dots, dye-sensitised and perovskite solar cells. A core focus of this project is the quantitative analysis of the impacts of major degradation mechanisms of fullerene-free OSCs as a function of their material and device design. The PI has already led the research efforts in quantitatively investigating the degradation of fullerenes and their impacts upon OSC stability, which laid the foundations for the development of the new research methodology proposed here. Based on the quantitative knowledge acquired, this proposal also aims to develop comprehensive material and device design rules capable of guiding the systematic optimisation of the stability of fullerene-free OSCs. This proposal will build upon the established research expertise and facilities in energy materials and devices at Cardiff University, in close collaboration with Swansea University and Imperial College London. The project will be carried out in partnership with 1) Eight19 Ltd., a UK-based SME specialising in the commercialisation of OSC products; 2) NSG group, a UK-based, world-leading company in glass and glazing products (e.g. glass-based PV products) 3) Armor group, a France-based company specialising in printing and coating technologies.