Plasmon-Induced Hot Carriers Transport in Metallic Ballistic Junctions

Abstract

The recent surge of theoretical research and experimental effort to devise plasmon-induced hot-carrier devices for radiation harvesting relies on the capability to separate charges at metal−semiconductor interfaces; however, the demand for momentum conservation of hot carriers at these interfaces sets an inherent limit to the quantum yield of such devices, making them currently less efficient than commonly used solar cells. Here we report experiments that suggest that ballistic whole-metal plasmon-induced hot carriers junctions based on atomic contacts could potentially be as efficient as semiconductor-based photovoltaic devices. Article pubs.acs.org/JPCC

Large-Area, Ensemble Molecular Electronics: Motivation and Challenges

“…In addition, evidence is accumulating for the critical role that roughness-derived protrusions have in NmJ. [62][63][64][65][66] 2.2.4. Statistical nature / Sensitivity: From all above-mentioned characteristics it is clear that the soft nature of molecules leads to current measured across a 1mJ to be stochastic, while that across an NmJ is the sum of many electron transfer events.…”

“…In situ photonic activation / recording were specifically demonstrated as technically feasible and highly informative complementary characterization of large-area molecular junctions. 63,64,[91][92][93][94][95][96] IETS can be done in NmJ's 94,97-99 though it requires low temperatures and long-time stability (i.e., impractical with most liquid contacts and common SPM's).…”

Optical Gating Electron Transport through Nonphotoresponisive Molecular Junctions

“…The logarithm values of the theoretical conductance exhibit a linear relationship, which means that the calculated molecular conductance values also follow ≈ × , in agreement with the experimental results. Notably, the measured conductance data are higher than the theoretically calculated data, and we attribute it to 1) direct transport of plasmon-induced hot carriers through the nanogap or photoassisted tunneling, which contributes as additional tunneling current 33,36 ; 2) as long as stable coordinate bonds between Au and N atoms are established, the hot carriers can extend into the benzene ring and envelop the N atom, thus enhancing the electron transmission 18 , which is not taken into consideration in the theoretical calculation. It can also be found that the wave functions for all the three kinds of junction are located on the molecular backbone instead of anchoring groups despite the fact that sp 2 21 hybridization shows a better conjugated effect, which indicates the anchoring groups contribute a poor conductivity.…”

“…1d shifted to a little bit higher conductance value when the junction was illuminated. We attribute this observation to 1) plasmon-induced hot carriers directly transfer across the nanogap between electrodes 31,33,36,37 , and 2) photo-assisted tunneling 5 . Both of them contribute a small proportion of the total current.…”

“…By taking advantage of the knowledge of plasmon-induced transport properties of metal point contacts 27,32,33 , we first investigated the electrical characteristics of bare gold electrodes with and without illumination in a shielding box. We further recorded the conductance of the target molecule in the presence of illumination by focusing a 632.8 nm He-Ne laser at the junction region.…”