内嵌团簇富勒烯的衍生化及其光电性质的研究

Endohedral clusterfullerenes can be considered as a kind of special fullerene derivatives, which are generated through endohedral modifications of fullerene cage. Impressive are their cluster-dependent properties including optical property, electronic property, electrochemical property and LUMO/HOMO energy levels. Therefore, endohedral clusterfullerenes might be one of unprecedented species showing huge molecular diversity and have potentials in fabricating multiple functional materials. In particular, trimetallic nitride fullerenes are very typical endohedral clusterfullerens. On one hand, recently published results suggested that some of these molecules have higher LUMO levels relative to that of C60 and might be a better electron acceptor than C60. On the other hand, considering their low first oxidation potentials, they might have, to some extent, electron-donating property. In the present research proposal, we plan to study the chemistry of clusterfullerenes, which might provide opportunities to access novel clusterfullerene derivatives having higher LUMO levels. Also, novel dyads, in which clusterfullerene works as either electron-donor or electron-acceptor, will be properly designed and prepared. In the following studies, these derivatives and dyads will be fully characterized to understand their photoelectrical properties and further used to fabricate the organic photovoltaic solar cells to estimate their application potentials.

内嵌团簇富勒烯是一类比较特殊的富勒烯笼内衍生物。其光学电学电化学性质以及LUMO/HOMO轨道能级均可以通过改变内嵌团簇类型和种类来调控，因此具有比富勒烯更为丰富的性质功能，有望用于多种功能材料包括光电材料的制备。近期发表的研究结果显示，一些内嵌三金属氮化物团簇的富勒烯具有较高的LUMO轨道能级，是一种很好的电子受体材料，同时由于其具有较低的氧化电位因此预期具有一定的给电子能力，或有可能是一种电子给体。本项目申请拟进一步研究内嵌团簇富勒烯的衍生化方法，通过调节衍生物结构，改善衍生物的稳定性，并进一步调解其LUMO/HOMO能级水平。分别以内嵌团簇富勒烯作为电子给体和受体单元，设计制备新型的二元偶极分子体系，研究内嵌团簇富勒烯作为电子受体或给体材料的光电光伏性质及相关器件的性质，并评估其应用前景。

以金属内包富勒烯Lu3N@C80作为电子给体，苝二酰亚胺衍生物作为电子受体，设计构筑具有线型结构以及光活性的电子授受体系。用多种实验方法以及基于密度泛函的理论计算对该体系进行了表征，以确认其结构，吸收光谱特征，电化学性质特征，前线轨道分布及能级水平以及体系激发态的瞬态吸收特征等。实验结果表明该线型体系的电荷分离态寿命可达到100ns的数量级，是柔性体系电荷分离态寿命的1000倍以上，说明Lu3N@C80-PDI体系的线型结构非常有利于电荷分离态的形成和稳定。