Department of Physics, School of Technology and Applied Sciences, São Paulo State University (UNESP), Presidente Prudente, SP, Brazil.
Professor Emeritus, University of Windsor, Windsor, On N9B 3P4, Canada.
Spectrochim Acta A Mol Biomol Spectrosc. 2019 Mar 15;211:221-226. doi: 10.1016/j.saa.2018.12.009. Epub 2018 Dec 4.
Organic thin films are at the forefront of basic studies and applications in the field of physics, chemistry, biochemistry and materials science. For example, the intrinsic supramolecular arrangement, or simply the formation of aggregates may alter the optical and electrical properties, which would impact the potential applications of the material. Here, an attempt is made to correlate the molecular structures of two perylene derivatives, bis butylimido perylene (BuPTCD) and bis phenethylimido perylene (PhPTCD), with their film formation, in particular, the supramolecular arrangement and the photoluminescent properties. Emission spectra show that the PhPTCD has a radiative efficiency (RE) higher than that for BuPTCD when both are in solutions (monomers). Complementary, regarding PVD films, UV-Vis absorption measurements reveal that PhPTCD forms, predominantly, J aggregates, which are responsible for perylene derivative emission. However, BuPTCD PVD films are found to provide higher RE than PhPTCD PVD film. This apparent controversy could be explained considering other features such as crystallinity and molecular organization. The PVD film of BuPTCD is crystalline while PhPTCD PVD film is amorphous; BuPTCD has an edge-on while PhPTCD has a face-on molecular organization in PVD films.
有机薄膜处于物理学、化学、生物化学和材料科学领域基础研究和应用的前沿。例如，内在的超分子排列，或者简单地说，聚集态的形成可能会改变光学和电学性质，从而影响材料的潜在应用。在这里，我们试图将两种苝衍生物——双丁基酰亚胺苝（BuPTCD）和双苯乙基酰亚胺苝（PhPTCD）的分子结构与其成膜特性，特别是超分子排列和光致发光性能联系起来。荧光光谱表明，在溶液（单体）中，PhPTCD 的辐射效率（RE）高于 BuPTCD。相比之下，对于 PVD 薄膜，紫外-可见吸收测量表明 PhPTCD 主要形成 J 聚集态，这是苝衍生物发光的原因。然而，BuPTCD 的 PVD 薄膜被发现提供了比 PhPTCD PVD 薄膜更高的 RE。考虑到其他特征，如结晶度和分子组织，这种明显的争议可以得到解释。BuPTCD 的 PVD 薄膜是结晶的，而 PhPTCD 的 PVD 薄膜是非晶的；BuPTCD 在 PVD 薄膜中具有边缘-on 分子组织，而 PhPTCD 具有面-on 分子组织。
