Control of low dimensionality in flexible hybrid inorganic-organic superlattices

The control of electron and phonon transport by manipulating dimensionality is essential for the performance of advanced electronic materials and devices, such as quantum electronics, thermoelectrics and superconductors, which may also lead to yet undiscovered, emergent electronic or thermal phenomena. In this study, we report a series of hybrid inorganic-organic superlattice structures, in which metallic TiS2 monolayers are spatially confined between soft and insulating organic molecules of varying thicknesses. By choosing different organic molecules that increase the interlayer distance, the electrons inside the TiS2 layers gradually become two-dimensional, with increasing density of states, as seen by their effective mass that increases from 5.3 to 8.6 m0, where m0 is the mass of a bare electron. In addition, density functional theory calculations confirm a transition of the electron distribution from bulk to two-dimensional, due to the suppressed interlayer coupling. This result demonstrates that the thermoelectric transport of two-dimensional electrons can be realized in a three-dimensional inorganic-organic superlattice, thus enabling access to the interesting properties of individual two-dimensional materials in the bulk form, which may provide new opportunities in flexible thermoelectrics