Guerrero Antonio, Garcia-Belmonte Germà
Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain.
Nanomicro Lett. 2017;9(1):10. doi: 10.1007/s40820-016-0107-3. Epub 2016 Oct 4.
Organic photovoltaic devices are on the verge of commercialization with power conversion efficiencies exceeding 10 % in laboratory cells and above 8.5 % in modules. However, one of the main limitations hindering their mass scale production is the debatable inferior stability of organic photovoltaic devices in comparison to other technologies. Adequate donor/acceptor morphology of the active layer is required to provide carrier separation and transport to the electrodes. Unfortunately, the beneficial morphology for device performance is usually a kinetically frozen state which has not reached thermodynamic equilibrium. During the last 5 years, special efforts have been dedicated to isolate the effects related to morphology changes taking place within the active layer and compare to those affecting the interfaces with the external electrodes. The current review discusses some of the factors affecting the donor/acceptor morphology evolution as one of the major intrinsic degradation pathways. Special attention is paid to factors in the nano- and microscale domain. For example, phase segregation of the polymer and fullerene domains due to Ostwald ripening is a major factor in the microscale domain and is affected by the presence of additives, glass transition temperature of the polymers or use of crosslinkers in the active layer. Alternatively, the role of vertical segregation profile toward the external electrodes is key for device operation, being a clear case of nanoscale morphology evolution. For example, donor and acceptor molecules actually present at the external interfaces will determine the leakage current of the device, energy-level alignment, and interfacial recombination processes. Different techniques have been developed over the last few years to understand its relationship with the device efficiency. Of special interest are those techniques which enable in situ analysis being non-destructive as they can be used to study accelerated degradation experiments and some will be discussed here.
有机光伏器件正处于商业化的边缘，实验室电池的功率转换效率超过10%，组件的功率转换效率超过8.5%。然而，阻碍其大规模生产的主要限制之一是与其他技术相比，有机光伏器件的稳定性存在争议且较差。活性层需要有合适的供体/受体形态，以实现载流子的分离和向电极的传输。不幸的是，对器件性能有益的形态通常是一种动力学冻结状态，尚未达到热力学平衡。在过去5年里，人们付出了特别的努力来分离与活性层内发生的形态变化相关的影响，并将其与影响与外部电极界面的影响进行比较。本综述讨论了影响供体/受体形态演变的一些因素，这是主要的内在降解途径之一。特别关注纳米和微观尺度领域的因素。例如，由于奥斯特瓦尔德熟化导致的聚合物和富勒烯域的相分离是微观尺度领域的一个主要因素，并且受到添加剂的存在、聚合物的玻璃化转变温度或活性层中交联剂的使用的影响。另外，垂直分离分布对外部电极的作用是器件运行的关键，这是纳米尺度形态演变的一个明显例子。例如，实际存在于外部界面的供体和受体分子将决定器件的漏电流、能级对准和界面复合过程。在过去几年里，已经开发出了不同的技术来理解其与器件效率的关系。特别令人感兴趣的是那些能够进行原位分析且无损的技术，因为它们可用于研究加速降解实验，本文将讨论其中一些技术。
