摘要
The incorporation of heavy atoms into molecular backbone is an extremely straightforward strategy for fine-tuning the optoelectronic properties of organic semiconductors.However,it is rarely studied in n-type small molecules.Herein,by selenium substitution of NDI3 HU-DTYM2,two Se-decorated core-expanded naphthalene diimides(NDI)derivatives DTYM-NDI3 HUDSYM(1)and NDI3 HU-DSYM2(2)were synthesized.In comparison with the reference S-containing compound NDI3 HUDTYM2,the highest occupied molecular orbital(HOMO)and lowest unoccupied molecular orbital(LUMO)energy levels of 1 and 2 were fine-tuned with?HOMO of about 0.2 e V,?LUMO of 0.1 e V and the narrowed HOMO-LUMO gaps.More surprisingly,the as-spun organic thin film transistors(OTFTs)based on 1 and 2 both showedμe,satvalues as high as1.0 cm2 V-1 s-1,which are 2-fold higher than that of NDI3 HU-DTYM2 with the same device structure and measurement conditions.In addition,the single crystal OFET devices based on Se-containing compound NDI2 BO-DSYM2 showed a highμe,satvalue of 1.30 cm2 V-1 s-1.The molecular packing of NDI2 BO-DSYM2 in single crystals(two-dimensional supramolecular structure formed by intermolecular Se···Se interactions)is quite different from that of a S-containing compound NDI-DTYM2(one dimensional supramolecular structure formed by intermolecularπ-πstacking).Therefore,the Se substitution can cause dramatic change about molecular stacking model,giving rise to high n-type OTFT performance.Our results demonstrated an effective strategy of the heavy atom effect for designing novel organic semiconductors.
基金
the National Natural Science Foundation of China(21522209,21790362,21502218)
the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB12010100)
the Science and Technology Commission of Shanghai Municipality(19XD1424700,18JC1410600)。
作者简介
Wenjie Han,Zhongli Wang,These authors contributed equally to this work;Corresponding authors:Congwu Ge(email:gecongwu@sioc.ac.cn);Corresponding authors:Xike Gao(email:gaoxk@mail.sioc.ac.cn)。
