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 NDI3HU-DTYM2, two Se-decorated core-expanded naphthalene diimides (NDI) derivatives DTYM-NDI3HU-DSYM (1) and NDI3HU-DSYM2 (2) were synthesized. In comparison with the reference S-containing compound NDI3HU-DTYM2, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of 1 and 2 were fine-tuned with AHOMO of about 0.2 eV, ALUMO of 0.1 eV and the narrowed HOMO-LUMO gaps. More surprisingly, the as-spun organic thin film transistors (OTFTs) based on 1 and 2 both showed μ_e,sat values as high as 1.0 cm² V⁻¹ s⁻¹, which are 2-fold higher than that of NDI3HU-DTYM2 with the same device structure and measurement conditions. In addition, the single crystal OFET devices based on Se-containing compound NDI2BO-DSYM2 showed a high value of 1.30 cm V⁻¹ s⁻¹. The molecular packing of NDI2BO-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 intermolecular π-π stacking). 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.

将重原子结合到分子主链中是微调有机半导体光电特性的极其简单的策略。但是，很少在n型小分子中进行研究。在此，通过NDI 3 HU-DTYM 2的硒取代，合成了两个硒修饰的芯膨胀萘二酰亚胺（NDI）衍生物DTYM-NDI 3 HU-DSYM（1）和NDI 3 HU-DSYM 2（2）。与参考含S的化合物NDI3HU-DTYM2相比，分别以约0.2 eV，0.1 eV的AHOMO对1和2的最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）的能级进行了微调。和缩小的HOMO-LUMO差距。更令人惊讶的是，基于1和2的初生有机薄膜晶体管（OTFT）均显示μe _，sat在相同的器件结构和测量条件下，该值高达1.0 cm ² V ^-1 s ^-1，比NDI3HU-DTYM2高2倍。此外，基于含硒化合物NDI2BO-DSYM2的单晶OFET器件显示出1.30 cm V ^-1 s ^-1的高值。NDI2BO-DSYM2在单晶中的分子堆积（由分子间Se⋯Se相互作用形成的二维超分子结构）与含S的化合物NDI-DTYM2（由分子间的π-π堆叠形成的一维超分子结构）有很大不同。 。因此，硒的取代会引起分子堆积模型的巨大变化，从而产生高n型OTFT性能。我们的结果证明了设计新的有机半导体的重原子效应的有效策略。