Molecular doping is an important strategy to improve the charge transport properties of organic semiconductors in various electronic devices. Compared to p-type dopants, the development of n-type dopants is especially challenging due to poor dopant stability against atmospheric conditions. In this article, we report the n-doping of the milestone naphthalenediimide-based conjugated polymer P(NDI2OD-T2) in organic thin film transistor devices by soluble anion dopants. The addition of the dopants resulted in the formation of stable radical anions in thin films, as confirmed by EPR spectroscopy. By tuning the dopant concentration via simple solution mixing, the transistor parameters could be readily controlled. Hence the contact resistance between the electrodes and the semiconducting polymer could be significantly reduced, which resulted in the transistor behaviour approaching the desirable gate voltage-independent model. Reduced hysteresis was also observed, thanks to the trap filling by the dopant. Under optimal doping concentrations the channel on-current was increased several fold whilst the on/off ratio was simultaneously increased by around one order of magnitude. Hence doping with soluble organic salts appears to be a promising route to improve the charge transport properties of n-type organic semiconductors.

分子掺杂是改善各种电子设备中有机半导体的电荷传输性能的重要策略。与p型掺杂剂相比，由于对大气条件的不良掺杂剂稳定性，n型掺杂剂的开发尤其具有挑战性。在本文中，我们通过可溶性阴离子掺杂剂报告了有机薄膜晶体管器件中基于里程碑的萘二甲酰亚胺共轭聚合物P（NDI2OD-T2）的n掺杂。如EPR光谱所证实的，掺杂物的添加导致在薄膜中形成稳定的自由基阴离子。通过简单的溶液混合来调节掺杂剂浓度，可以很容易地控制晶体管参数。因此，电极和半导体聚合物之间的接触电阻可以大大降低，这导致晶体管的性能接近理想的栅极电压独立模型。由于掺杂物填充了陷阱，因此还观察到了滞后现象的减少。在最佳掺杂浓度下，通道的导通电流增加了几倍，而开/关比同时增加了大约一个数量级。因此，用可溶性有机盐掺杂似乎是改善n型有机半导体的电荷传输性质的有前途的途径。