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Effect of Nitrogen Atoms on Structures and Electron Transport of N-heteropentacenes Devices.

Pentacene polycyclic aromatic hydrocarbons are the most promising organic semiconductor materials among aromatic compounds due to their potential optoelectronic properties. Introducing N atoms into the main chain of pentacene is supposed to tune the electronic structure and develop new high-performance organic molecular devices. Herein, we have investigated the electron transport properties of N-heteropentacene consisting of different numbers, positions, and valence states of N atoms using density functional theory (DFT) and nonequilibrium Green's function (NEGF) method. The results show that the transport properties of N-heteropentacene are strongly dependent on whether the C-N is a single or double bond. For devices with C-N double bonds, the behavior of current changes with voltage is consistent, and its electron transport properties are independent of the number and position of N atoms. Compared to C-N double bonds devices, C-N single-bond devices have an earlier negative differential resistance (NDR) effect and exhibit significant rectification effects. Moreover, threshold voltages exist within certain bias voltages for different numbers of N atoms in C-N single-bonds devices, and even a second NDR effect will occur. These studies guide to design of performance-enhancing molecular devices by manipulating the molecular structure of N-heteropentacene.