Kilbride Rachel C, Spooner Emma L K, Burg Stephanie L, Oliveira Bárbara L, Charas Ana, Bernardo Gabriel, Dalgliesh Robert, King Stephen, Lidzey David G, Jones Richard A L, Parnell Andrew J
Department of Chemistry, The University of Sheffield, Dainton Building, Brook Hill, Sheffield, S3 7HF, United Kingdom.
Department of Physics and Astronomy, The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH, United Kingdom.
Small. 2024 Aug;20(33):e2311109. doi: 10.1002/smll.202311109. Epub 2024 Apr 10.
Controlling the nanomorphology in bulk heterojunction photoactive blends is crucial for optimizing the performance and stability of organic photovoltaic (OPV) technologies. A promising approach is to alter the drying dynamics and consequently, the nanostructure of the blend film using solvent additives such as 1,8-diiodooctane (DIO). Although this approach is demonstrated extensively for OPV systems incorporating fullerene-based acceptors, it is unclear how solvent additive processing influences the morphology and stability of nonfullerene acceptor (NFA) systems. Here, small angle neutron scattering (SANS) is used to probe the nanomorphology of two model OPV systems processed with DIO: a fullerene-based system (PBDB-T:PCBM) and an NFA-based system (PBDB-T:ITIC). To overcome the low intrinsic neutron scattering length density contrast in polymer:NFA blend films, the synthesis of a deuterated NFA analog (ITIC-d) is reported. Using SANS, new insights into the nanoscale evolution of fullerene and NFA-based systems are provided by characterizing films immediately after fabrication, after thermal annealing, and after aging for 1 year. It is found that DIO processing influences fullerene and NFA-based systems differently with NFA-based systems characterized by more phase-separated domains. After long-term aging, SANS reveals both systems demonstrate some level of thermodynamic induced domain coarsening.
控制本体异质结光活性共混物的纳米形貌对于优化有机光伏（OPV）技术的性能和稳定性至关重要。一种有前景的方法是改变干燥动力学，进而使用诸如1,8 - 二碘辛烷（DIO）之类的溶剂添加剂来改变共混物薄膜的纳米结构。尽管这种方法已在包含基于富勒烯受体的OPV系统中得到广泛证明，但尚不清楚溶剂添加剂处理如何影响非富勒烯受体（NFA）系统的形貌和稳定性。在此，小角中子散射（SANS）用于探测用DIO处理的两种模型OPV系统的纳米形貌：一种基于富勒烯的系统（PBDB - T:PCBM）和一种基于NFA的系统（PBDB - T:ITIC）。为了克服聚合物:NFA共混物薄膜中固有的低中子散射长度密度对比度，报道了一种氘代NFA类似物（ITIC - d）的合成。使用SANS，通过对制备后、热退火后以及老化1年后的薄膜进行表征，提供了对基于富勒烯和NFA系统的纳米尺度演变的新见解。研究发现，DIO处理对基于富勒烯和NFA的系统的影响不同，基于NFA的系统具有更多相分离的区域。长期老化后，SANS表明这两种系统都表现出一定程度的热力学诱导的畴粗化。
