Despite the high performance of poly[N,N′-bis(2-octyldodecyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt-5,5′-(2,2′-bithiophene) (pNDI-2T) in field-effect transistors, literature reports on its electrical conductivity upon n-doping using various n-dopants seem to show an upper limit in the range of 10⁻³ S cm⁻¹. Here we demonstrate that by using the benzyl viologen radical cation (BV˙⁺) as an n-dopant, we have achieved electrical conductivity as high as 1.34 × 10⁻² S cm⁻¹ with minimum contact resistance. Moreover, electrical conductivities of the BV˙⁺-doped pNDI-2T films were found to be very stable; less than 30% degradation at both 100 °C for 24 h and room temperature for two weeks in a glovebox. This is in stark contrast with the commonly used tetrakis(dimethylamino)ethylene (TDAE) where the electrical conductivity of TDAE-doped pNDI-2T films falls rapidly within hours at room temperature. Detailed studies suggest that BV˙⁺ facilitates charge transport of pNDI-2Tvia reducing the electron hopping distance and minimizing structural rearrangement involving electron transfer. Our results may pave a way towards high electrical conductivity for n-doped conjugated polymers.

中文翻译：

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苄基紫罗碱自由基阳离子：聚萘二甲酰亚胺-联噻吩的有效正掺杂剂

尽管聚高性能[ Ñ，Ñ ' -双（2-辛基十二烷基）-1,4,5,8-萘二酰亚胺-2,6-二基] - ALT -5,5' - （2,2'-联噻吩）（pNDI-2T）（pNDI-2T），文献报道了在使用各种n掺杂剂进行n掺杂时其电导率似乎显示出10 ^-3 S cm ^-1的上限。在此我们证明，通过使用苄基紫罗兰自由基自由基阳离子（BV˙ ⁺）作为n型掺杂剂，我们以最小的接触电阻实现了高达1.34×10 ^-2 S cm ^-1的电导率。此外，BV˙ ⁺掺杂的电导率发现pNDI-2T薄膜非常稳定；在手套箱中在100°C下放置24 h和在室温下放置2周，降解率均低于30％。这在与常用的四（二甲基氨基）乙烯（形成鲜明对比TDAE），其中的导电性TDAE掺杂PNDI-2T膜在室温下小时内快速下降。详细的研究表明，BV ⁺通过减小电子跳跃距离并最小化涉及电子转移的结构重排而促进了pNDI-2T的电荷传输。我们的结果可能为n掺杂共轭聚合物的高电导率铺平道路。