Zinc(II) complexes of azadipyrromethene: Effect of nature and placement of solubilizing groups on structural, thermal, electrochemical and optical properties
Zinc(II) complexes of azadipyrromethene: Effect of nature and placement of solubilizing groups on structural, thermal, electrochemical and optical properties
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DOI：
10.1016/j.dyepig.2022.110858
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发表时间：
2022-10
影响因子：
4.5
通讯作者：
J. Jimenez;Quynh Tran;M. H. Pugh;Christina D. Brancel;A. Rheingold;G. Sauvé
中科院分区：
文献类型：
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作者：
J. Jimenez;Quynh Tran;M. H. Pugh;Christina D. Brancel;A. Rheingold;G. Sauvé
氮杂二吡咯亚甲基锌(II)配合物是非平面发色团，在可见光到近红外区域具有强吸收性，是用于有机太阳能电池的有前途的n型材料。为了增加溶解度并调整其性质，我们在双[2,6-二苯基乙炔基-1,3,7,9-四苯基氮杂二吡咯亚甲基]锌(II) (Zn(WS3)2)的远端或近端苯基上掺入了己基或己氧基增溶基团。晶体结构证实了这些类型的配合物的典型扭曲四面体几何形状，并表明远端苯基上的增溶基团远离共轭核心延伸，而近端苯基上的基团与其他配体相互作用。差示扫描量热法测量表明，远端取代配合物晶体具有两个吸热峰：增溶基团“熔化”和配合物熔化，而近端取代配合物则显示出一个放热结晶峰和一个吸热熔化峰。基于 ADP 的复合物的电化学和光学特性如预期的那样变化：与远端取代相比，近端取代处富电子基团的存在导致氧化电位更低、HOMO 水平更高、红移吸收和更低的光学间隙，并且己氧基的影响大于己基。热退火后，己氧基取代的复合物薄膜强烈聚集，并在偏光显微镜下显示出晶体特征，表明己氧基驱动有序自组装，特别是当放置在远端苯基上时。使用增溶基团引导这些非平面发色团进行固态自组装的能力有可能提高其载流子迁移率和在有机太阳能电池和光电探测器等光电应用中的性能。
Zinc(II) complexes of azadipyrromethenes are non-planar chromophores with strong absorption in the visible to NIR and are promising n-type materials for organic solar cells. To increase solubility and tune their properties, we incorporated hexyl or hexyloxy solubilizing groups either on the distal or proximal phenyls ofbis[2,6-diphenylethynyl-1,3,7,9-tetraphenyl azadipyrromethene] zinc(II) (Zn(WS3)2). Crystal structures confirm the typical distorted tetrahedral geometry for these types of complexes and show that the solubilizing groups on the distal phenyls extend away from the conjugated core whereas groups on proximal phenyls interact with the other ligand. Differential scanning calorimetry measurement indicated that crystals of distal-substituted complexes have two endothermic peaks: solubilizing groups ‘melting’ and complex melting, whereas the proximal-substituted complexes show one exothermic crystallization peak and one endothermic melting peak. Electrochemical and optical properties varied as expected for ADP-based complexes: the presence of electron rich groups at the proximal substitutions resulted in lower oxidation potentials, higher HOMO levels, red-shifted absorption and lower optical gap than distal substitutions, and the effect was greater for hexyloxy than hexyl. Upon thermal annealing, films of the hexyloxy-substituted complexes strongly aggregated and showed crystal features under a polarized microscope, indicating that hexyloxy groups drive ordered self-assembly, especially when placed on distal phenyls. The ability to guide solid-state self-assembly of these non-planar chromophores using solubilizing groups have the potential to improve their charge carrier mobility and performance in opto-electronic applications such as organic solar cells, and photodetectors.