| Autor: |
Eckstein KH; Institute of Physical and Theoretical Chemistry, Julius Maximilian University Würzburg , Würzburg 97074, Germany., Hartleb H; Institute of Physical and Theoretical Chemistry, Julius Maximilian University Würzburg , Würzburg 97074, Germany., Achsnich MM; Institute of Physical and Theoretical Chemistry, Julius Maximilian University Würzburg , Würzburg 97074, Germany., Schöppler F; Institute of Physical and Theoretical Chemistry, Julius Maximilian University Würzburg , Würzburg 97074, Germany., Hertel T; Institute of Physical and Theoretical Chemistry, Julius Maximilian University Würzburg , Würzburg 97074, Germany.; Röntgen Research Center for Complex Material Systems, Julius Maximilian University Würzburg , Würzburg 97074, Germany. |
| Abstrakt: |
Doping by chemical or physical means is key for the development of future semiconductor technologies. Ideally, charge carriers should be able to move freely in a homogeneous environment. Here, we report on evidence suggesting that excess carriers in electrochemically p-doped semiconducting single-wall carbon nanotubes (s-SWNTs) become localized, most likely due to poorly screened Coulomb interactions with counterions in the Helmholtz layer. A quantitative analysis of blue-shift, broadening, and asymmetry of the first exciton absorption band also reveals that doping leads to hard segmentation of s-SWNTs with intrinsic undoped segments being separated by randomly distributed charge puddles approximately 4 nm in width. Light absorption in these doped segments is associated with the formation of trions, spatially separated from neutral excitons. Acceleration of exciton decay in doped samples is governed by diffusive exciton transport to, and nonradiative decay at charge puddles within 3.2 ps in moderately doped s-SWNTs. The results suggest that conventional band-filling in s-SWNTs breaks down due to inhomogeneous electrochemical doping. |
