| AVS 62nd International Symposium & Exhibition | |
| 2D Materials Focus Topic | Thursday Sessions |
| Session 2D-ThP |
| Session: | 2D Materials Focus Topic Poster Session |
| Presenter: | Joshua Hihath, University of California, Davis |
| Authors: | J. Hihath, University of California, Davis C.E. McCold, University of California, Davis Q. Fu, University of California, Davis J.Y. Howe, Hitachi High-Technologies Corporation |
| Correspondent: | Click to Email |
Molecule-nanoparticle hybrid systems have emerged as promising materials for applications ranging from chemical sensing to nanoscale electronics. However, creating reproducible and repeatable 2-dimensional composite materials with precise electronic properties has remained an important challenge to the implementation of these meta-materials. Understanding the sources of variation that dominate the charge transport properties of these systems is essential for the advancement of nanoparticle-array based devices. In this work, we use a combination of charge-transport measurements, electron microscopy, optical characterization, and chemical ligand exchange to determine the role of morphology, structure, and array interconnection on the charge transport properties of 2-dimensional, monolayer arrays of molecularly-interlinked gold nanoparticles. Using these techniques we are able to determine the role of assembly-dependent, particle dependent, and molecule dependent defects on the conductivities of the monolayer films. These results demonstrate that micron-scale assembly processes dominate the dispersion of the conductance values, and result in order-of-magnitude differences in the conductance values, while nanoscale properties related to the nanoparticle and ligand features dictate the mean value of the conductance. By performing a systematic study of the conductance of these arrays as a function of nanoparticle size we are able to extract the carrier mobility for specific molecular ligands. We show that nanoparticle dispersion correlates with the void density in the array, and that because of this correlation it is possible to accurately determine the void density within the array directly from conductance measurements. These results demonstrate that conductance-based measurements can be used to accurately and non-destructively determine the morphological and structural properties of these hybrid arrays, and thus provide a characterization platform that helps move 2-dimensional nanoparticle arrays toward robust and reproducible electronic systems. Based upon this understanding, it is then possible to control the conductance values of the hybrid arrays by tuning both the distance between nanoparticles, and the conjugation of the molecules interlinking the nanoparticles. This control allows the conductance of the 2D films to be tuned over a range of ~7 orders of magnitude.