Is there such a thing as a molecular organic alloy?
Is there such a thing as a molecular organic alloy?
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DOI：
10.1039/c9mh01351b
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发表时间：
2020-01-01
影响因子：
13.3
通讯作者：
Forrest, Stephen R.
中科院分区：
文献类型：
--
作者：
Huang, Xinjing;Liu, Xiao;Forrest, Stephen R.
在无机材料中，合金是两种或更多种物质的混合物，其通常表现出与其成分不同的电子和/或物理性质。在有机体系中，还提出了形成包含分子有机材料的混合物的“分子合金”。我们通过研究三元体系的光电性质来测试这一概念的有效性，该三元体系先前已被确定为形成分子受体合金，即聚（3-己基噻吩）（P3 HT）供体与两个受体茚-C-60双加合物（ICBA）和苯基-C-61-丁酸甲酯（PC 61 BM）的共混物[R. A. Street等人，J. Am.化学会，2013，135，986-989]。使用光电子能谱，我们发现，ICBA：PC61 BM共混物显示出相同的最高占据分子轨道和激子能量的ICBA，表明没有一个新的激子状态的共混物。此外，三元共混物的电荷转移态光谱被发现包括一个简单的线性叠加相应的二元。从这些结果中，没有发现新的，新兴的电子状态的证据，以支持在这个系统中的分子合金的存在。据我们所知，目前还没有明确的证据表明在任何有机半导体系统中存在合金。我们讨论的标准，应满足的分子有机合金和程序需要明确的识别。
In inorganic materials, an alloy is a mixture of two or more substances that generally exhibits electronic and/or physical properties that differ from those of its constituents. In organic systems, the formation of a "molecular alloy'' comprising mixtures of molecular organic materials has also been proposed. We test the validity of this concept via the study of the optoelectronic properties of a ternary system that has previously been identified to form a molecular acceptor alloy, namely a blend of a poly(3-hexylthiophene) (P3HT) donor, with two acceptors indene-C-60 bisadduct (ICBA) and phenyl-C-61-butyric acid methyl ester (PC61BM) [R. A. Street, et al., J. Am. Chem. Soc., 2013, 135, 986-989]. Using photoelectron spectroscopy, we find that the ICBA:PC61BM blend shows the same highest occupied molecular orbital and exciton energies as that of ICBA, indicating the absence of a new exciton state in the blend. Furthermore, charge transfer state spectra of ternary blends are found to comprise a simple linear superposition of the corresponding binaries. From these results, no evidence of new, emergent electronic states is found to support the existence of a molecular alloy in this system. To our knowledge there is as yet no clear evidence of the existence of an alloy in any organic semiconductor system. We discuss the criteria that should be met by a molecular organic alloy and procedures needed for their unambiguous identification.