Field-Induced Broadening of Electroabsorption Spectra of Semiconductor Nanorods and Nanoplatelets

We theoretically study the broadening of optical absorption spectra of monodisperse ensembles of randomly oriented nanorods and nanoplatelets exposed to a static electric field. It is found that the weaker quantum confinement inside nanoplatelets results in a much stronger field impact on their absorption than on the absorption of nanorods. The most notable manifestation of this impact is that the widths of the absorption lines in the nanoplatelets' spectra peak as functions of the electric field strength. Both the maximal widths and the corresponding optimal field strengths are found to decrease with the largest dimensions of the nanoplatelets. In sharp contrast to this, the broadening of the nanorods' absorption grows monotonously and saturates with the field strength. The high tunability of electroabsorption and the possibility to maximize its efficiency, revealed by our study, suggest semiconductor nanoplatelets as a promising material base for the next-generation electro-optic devices.