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）的一个非常有前途的替代品，因为它是一种重量轻、灵活、一次性和真正的建筑集成光伏技术，具有极快的能源回报。然而，它们有限的稳定性现在已被广泛认为是其商业化的常见瓶颈，暴露于各种环境因素（例如光、热、氧、湿度）会导致其性能迅速损失，其起源通常仍不清楚。近二十年来，富勒烯作为电子受体和传输材料在有机太阳能电池（OSCs）中得到了广泛的应用。直到最近3-4年，非富勒烯受体材料作为一种更高效、更低成本、更通用的富勒烯替代品，被带到了OSCs发展的前沿，无富勒烯OSCs的性能已经大大超过了基于富勒烯的OSCs。然而，到目前为止，大多数研究工作都只致力于进一步优化它们的效率，在理解它们的稳定性和降解机制方面留下了明显的差距，这是它们商业化的另一个关键考虑因素。本提案旨在解决在开发稳定的无富勒烯osc中三个非常重要但尚未解决的问题：1 .导致无富勒烯osc降解的机制是什么；我们能否全面定量地理解这些退化机制？是什么控制着这些退化机制？如何解决它们？为了回答这些问题，本提案将开发一种新的研究方法来研究盐含量的降解，这是以前没有建立的。通过对在局部控制环境中降解的光伏薄膜和器件进行时间分辨和相互关联的光学、结构和功能分析，该方法能够捕获在降解过程中导致器件性能损失的基本过程的实时信息，从而建立降解机制与由此产生的OSC降解行为之间的定量关系。具体来说，几个先进的，决定性能的设备参数的演变（即时间分辨），以及在同一降解过程中的化学和结构变化（即相互关联），将被记录和进一步分析，以重建盐碳降解行为。该项目只研究无富勒烯的太阳能电池，但新方法可以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。该项目的一个核心重点是定量分析无富勒烯osc的主要降解机制的影响，作为其材料和设备设计的功能。PI已经在定量研究富勒烯的降解及其对盐盐稳定性的影响方面领导了研究工作，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，本提案还旨在制定能够指导无富勒烯osc稳定性系统优化的综合材料和器件设计规则。该提案将以卡迪夫大学在能源材料和设备方面已建立的研究专业知识和设施为基础，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)Eight19 Ltd.合作开展，这是一家总部位于英国的中小型企业，专门从事OSC产品的商业化；2) NSG集团，总部位于英国，在玻璃和上釉产品（如玻璃基光伏产品）方面处于世界领先地位；3)Armor集团，总部位于法国，专注于印刷和涂层技术。

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.