Bernardo Gabriel, Melle-Franco Manuel, Washington Adam L, Dalgliesh Robert M, Li Fankang, Mendes Adélio, Parnell Steven R
LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto Rua Dr Roberto Frias 4200-465 Porto Portugal
CICECO-Aveiro Institute of Materials, Department of Chemistry, University of Aveiro 3810-193 Aveiro Portugal.
RSC Adv. 2020 Jan 29;10(8):4512-4520. doi: 10.1039/c9ra08019h. eCollection 2020 Jan 24.
Fullerene derivatives are used in a wide range of applications including as electron acceptors in solution-processable organic photovoltaics. We report agglomeration of fullerene derivatives in optically opaque solutions of PCBM and PCBM, with concentrations ranging from 30 mg mL up to 90 mg mL, in different solvents with relevance to organic photovoltaics, using a novel neutron scattering technique, Spin-Echo Small Angle Neutron Scattering (SESANS). From SESANS, agglomerates with correlation lengths larger than 1 μm are found in some PCBM solutions, in contrast no agglomerates are seen in PCBM solutions. These results clearly show that PCBM is fundamentally more soluble than PCBM in the solvents commonly used in photovoltaic inks and corroborating similar observations previously achieved using other experimental techniques. Computer models are presented to study the energetics of solution and agglomeration of both species, ascribing the difference to a kinetic effect probably related to the larger anisotropy of PCBM. Also, this work showcases the power of SESANS to probe agglomerates of fullerene derivatives in completely opaque solutions for agglomerates of the order of one to several microns.
富勒烯衍生物被广泛应用于诸多领域，包括用作可溶液加工的有机光伏电池中的电子受体。我们使用一种新型中子散射技术——自旋回波小角中子散射（SESANS），报告了在与有机光伏相关的不同溶剂中，浓度范围从30毫克/毫升到90毫克/毫升的聚碳酸亚丙酯甲酯（PCBM）和聚碳酸亚丙酯甲酯（PCBM）的光学不透明溶液中富勒烯衍生物的团聚情况。通过SESANS发现，在一些PCBM溶液中存在相关长度大于1微米的团聚体，相比之下，在PCBM溶液中未观察到团聚体。这些结果清楚地表明，在光伏油墨常用的溶剂中，PCBM从根本上比PCBM更易溶解，这也证实了先前使用其他实验技术所得到的类似观察结果。本文还展示了计算机模型，用于研究这两种物质在溶液中的能量学和团聚情况，将这种差异归因于可能与PCBM更大的各向异性相关的动力学效应。此外，这项工作展示了SESANS在探测完全不透明溶液中尺寸为一到几微米量级的富勒烯衍生物团聚体方面的能力。
