Semiconducting Cellulose Nanocrystal-Polyfluorene Emissive Materials in Organic Light-Emitting Diodes
Semiconducting Cellulose Nanocrystal-Polyfluorene Emissive Materials in Organic Light-Emitting Diodes
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DOI：
10.1021/acsapm.1c00489
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发表时间：
2021-07
影响因子：
5
通讯作者：
Allen C. Chang;M. B. Messikh;Maximilian Kaiser-;K. Carter
中科院分区：
文献类型：
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作者：
Allen C. Chang;M. B. Messikh;Maximilian Kaiser-;K. Carter
纤维素纳米晶体 (CNC) 通过半导体聚芴接枝物进行功能化，并用于蓝色发射有机发光二极管 (OLED) 器件。用表面结合的芳基卤化物功能化的 CNC 通过 Ni(0) Yamamoto 交叉偶联与共轭聚 (9,9-二己基芴) 接枝。复合材料 g-PF-CNC 具有通过酯裂解反应分离的聚合物接枝物，并通过 MALDI-ToF、UV-vis 和 TGA 进行分析。接枝聚合物材料的性能得到了确定，其重均分子量为Mw∼4000 Da，具有与聚芴互连的网络状CNC，聚合物负载量高于10 wt%。 OLED 是在 ITO/玻璃基板上制造的，使用 g-PF-CNC 作为发射层，加上聚（4-正己基三苯胺）中间层。从 0-8 V 的 I-V 扫描显示，开启电压 (Von) 约为 4.5 V，随后稳定增加的电流和标准聚芴发射器的蓝色发射特性。将复合材料 OLED 的发射特性与标准聚芴 OLED 进行比较，以突出发射行为的相似性。在两种类型的器件中都在相似的波长处发现了激子和准分子发射峰。总体发射强度的差异很大，但很容易用存在的发射材料量的巨大差异来解释。观察到激子和准分子发射相对强度的差异，这可能是由于低强度读数、轻微氧化或接枝行为所致。这项工作的结果强调了用于生产复合材料的合成和分析方法，该复合材料直接将半导体发射器聚合物与可持续的纳米级基材材料结合在一起。
Cellulose nanocrystals (CNCs) were functionalized with semiconducting polyfluorene grafts and employed in blue emissive organic light-emitting diode (OLED) devices. CNCs functionalized with surface bound aryl halides were grafted with conjugated poly (9,9-dihexyl fluorenes) through Ni(0) Yamamoto cross-coupling. The composite material, g-PF-CNC, exhibited polymer grafts that were isolated through an ester cleavage reaction and analyzed via MALDI-ToF, UV–vis, and TGA. Grafted polymer material properties were ascertained, demonstrating a weight average molecular weight ofMw∼4000 Da, network-like CNCs interlinked with polyfluorenes, and a polymer loading above 10 wt %. OLEDs were fabricated on ITO/glass substrates using g-PF-CNC as the emissive layer coupled with a poly (4-n-hexyl triphenylamine) interlayer.I–Vsweeps from 0–8 V revealed turn on voltages (Von) around 4.5 V followed by a steadily increasing current and blue emission characteristics of standard polyfluorene emitters. Emissive characteristics of the composite material OLED were compared with a standard polyfluorene OLED to highlight similarities in emission behaviors. Excitonic and excimeric emission peaks were found at similar wavelengths in both types of devices. Differences in overall emissive intensity were large but readily explainable by large differences in the amount of emitting material present. Differences in the relative intensities of the excitonic and excimeric emissions were observed, potentially manifesting due to low intensity readings, slight oxidations, or grafting behavior. The results of this work highlight synthetic and analytical methods used to produce a composite material which directly binds a semiconducting emitter polymer with a sustainable nanoscale substrate material.