High resolution mapping of performance and degradation mechanisms in printable photovoltaic devices

可以在低温下从溶液中加工的光伏材料提供了一种低成本和低嵌入能量的光伏模块的途径，该模块具有集成到建筑物和其他基础设施中以大规模产生清洁电力的潜力。有机光伏（OPV）已经引起了强烈的研究兴趣;在效率和制造技术方面的令人印象深刻的改进已经得到证明。卤化铅钙钛矿太阳能电池（PSC）基于一种新发现的活性层材料，并且随着最近对器件结构和工艺的优化，在寿命开始效率方面已经显示出根本性的改善。然而，这两种技术类型都面临着运行中功率转换效率损失的挑战，即使它们被认为能够稳定15- 20%的效率。这种装置的有限的操作稳定性抑制了它们的广泛商业应用。为了克服这一点，有必要了解效率损失的来源，无论是在开始的生活和老化期间在典型的操作环境。到目前为止，新型PV器件稳定性的大多数研究已经达到了不同材料或器件结构在不同环境中的性能参数演变的经验研究，并且科学注意力主要集中在光活性层的氧化稳定性上。相对较少的注意力已经支付给电极和夹层，即使这些层往往是第一个失败，此外，他们是部分负责保护有源层。此外，大多数性能指标探测宏观器械性能，尽管成像方法已用于观察老化过程中的异质材料特性，但标测技术尚未用于详细了解电流和电压损失的化学、电化学和物理机制。该提案旨在开发一套相互关联的实验技术，以探索两类领先的可印刷光伏（PV）材料，有机光致发光（OPV）和有机卤化物钙钛矿太阳能电池（PSC）中的基本机制。我们的方法是开发和适应二维映射技术，探测当地的化学和电子状态的材料和联合收割机结合它们与设备规模的电气测量，结构表征和建模，以分析退化机制，以确定当地的条件，导致退化和设计策略，以抑制故障机制的进展。映射工具将被开发，具有在模块制造和质量控制期间应用的潜力。

PV materials that can be processed from solution at low temperature offer a route to low cost and low emebedded energy PV modules with potential for integration into buildings and other infrastructure to generate clean electricity on a large scale. Organic PV (OPV) has attracted intense research interest; impressive improvements in efficiency and in fabrication knowhow have been demonstrated. Lead halide perovskites solar cells (PSC) are based on a newly rediscovered active layer material and have shown radical improvements in start-of-life efficiency with recent optimisation of device structure and processing. However both technology types are challenged by losses in power conversion efficiency under operation, even though they are believed capable of stabilised efficiency of 15-20%. The limited operational stability of such devices inhibits their widespread commercial application. To overcome this there is a need to understand the sources of efficiency loss, both at start-of-life and during ageing in typical operating environments. Until now, most studies of novel PV device stability have amounted to empirical studies of the evolution of performance parameters for different materials or device structures in different environments, and scientific attention has focussed largely on the oxidative stability of the photoactive layer. Relatively little attention has been paid to the electrodes and interlayers, even though these layers are often the first to fail and additionally they are partly responsible for protecting the active layers. In addition, most performance metrics probe the macroscopic device performance and although imaging methods have been used to observe heterogeneous material properties during ageing mapping techniques have not yet been used to provide detailed insight into the chemical, electrochemical and physical mechanism of current and voltage loss. This proposal seeks to develop a set of interlinked experimental techniques to probe the basic mechanisms underpinning device degradation and failure in two leading classes of printable photovoltaic (PV) materials, organic photovoltaics (OPV) and organohalide perovskite solar cells (PSCs). Our approach is to develop and adapt two-dimensional mapping techniques that probe the local chemical and electronic state of the materials and combine them with device-scale electrical measurement, structural characterisation and modelling in order to analyse the degradation mechanisms, to identify the local conditions that lead to degradation and to design strategies to inhibit the progression of failure mechanisms. The mapping tools will be developed with the potential to be applied during module manufacture and quality control.