Discrete charge transfer in nanoparticle solid films

Abstract

A brief overview of the recent progress in single electron transfer (SET) in nanoparticle solid films is presented. In these studies, Langmuir-based techniques were employed to control the interparticle interactions, and the ensemble conductivity was evaluated by electrochemical measurements. Deliberate manipulation of the ensemble structure and temperature led to the optimization of the conductivity properties where SET was initiated across a nanoparticle solid film.

Surface‐Mediated Interconnections of Nanoparticles in Cellulosic Fibrous Materials toward 3D Sensors

“…QCC was reported for isolated gold NPs (1.1–1.9 nm in diameter) and 3D array of gold NPs (2.2 and 1.6 nm in diameter) isolated from one another by insulating ligands. [ 25–27 ] Given the constant current ( I , 10–100 µA) and the oscillatory R – t curve, the QCC was then estimated by integration of the charges under the V – t curve ( C QCC = Q / V = I Δ t / V ). For example, from data in Figure 3b, the average C QCC = 1.0 × 10 −4 F. By further considering the single particle's theoretical capacitive charging (see the Experimental Section for details of the theoretical equations and parameter descriptions), we estimated that the particle radius responsible for the QCC to be 0.6–0.9 nm is in a close agreement with the experimentally determined radius for the NCs (0.7 nm) in the bimodal distribution (Figure S1, Supporting Information).…”

Single electron transfer in thermally annealed nanoparticle dropcast thick films

“…It should be noted that the activation energy of the as-prepared film is very close to those found with dropcast films of nanoparticles of similar structures 11 and the E a value of the annealed film is consistent with that of nanoparticle Langmuir-Blodgett monolayers that exhibit clear SET features. [2][3][4] As mentioned earlier, rampant structural defects within the as-prepared particle films lead to effective percolation pathways for interparticle charge transport, whereas after thermal annealing the energetic barrier to charge transfer increases because of the ordered arrangements of the nanoparticle cores in the organic matrix.…”

“…1 More recently, single electron transfer ͑SET͒ across a nanoparticle monolayer film has also been observed in solid-state electronic conductivity study by deliberate manipulation of the nanoparticle structures and interparticle arrangements. [2][3][4] However, with nanoparticle thick films, particularly particle films that are prepared by dropcasting a concentrated solution onto an electrode surface, the current-potential profiles are typically featureless. This is largely attributed to the rampant structural defects within the particle films that render it difficult to resolve the individual charging step.…”

“…The optimal condition is when neighboring particles are fully intercalated, namely, the interparticle separation was about one chainlength of the particle protecting ligands. [2][3][4] The fact that annealed particle dropcast films exhibit clear SET features implies that in comparison to the as-prepared particle film, drastic structural rearrangements of the nanoparticles occurred in the ensemble ͑as depicted in the lower inset to Fig. 2͒.…”

Close‐Packed Gold‐Nanocrystal Assemblies Deposited with Complete Selectivity into Lithographic Trenches

“…[9,10] Integration of nanocrystal assemblies in scaleable devices requires their selective organization at discrete locations on a semiconductor substrate. The idealized nanocrystal-device architecture is a combination of top-down lithography for pattern features >50 nm in size and bottom-up assembly for critical dimensions below this limit.…”