Bicyclic-ring base doping induces n-type conduction in carbon nanotubes with outstanding thermal stability in air
Shohei Horike, Qingshuo Wei, Kouki Akaike, Kazuhiro Kirihara, Masakazu Mukaida, Yasuko Koshiba, Kenji Ishida
Abstract
The preparation of air and thermally stable n-type carbon nanotubes is desirable for their further implementation in electronic and energy devices that rely on both p- and n-type material. Here, a series of guanidine and amidine bases with bicyclic-ring structures are used as n-doping reagents. Aided by their rigid alkyl functionality and stable conjugate acid structure, these organic superbases can easily reduce carbon nanotubes. n-Type nanotubes doped with guanidine bases show excellent thermal stability in air, lasting for more than 6 months at 100 °C. As an example of energy device, a thermoelectric p/n junction module is constructed with a power output of ca. 4.7 μW from a temperature difference of 40 °C.