Abstract
Abstract Since its first observation in 2014, plasmoelectric potential (PEP) has drawn a great deal of research interest in all-metal optoelectronics and photochemistry. As an optical thermodynamic phenomenon induced by the electron number dependent equilibrium temperature in plasmonic nanostructures, the early theoretical model developed for calculating PEP is only applicable to Mie-resonant nanostructures, such as a gold nanosphere on a conductive indium tin oxide (ITO) substrate, where the transfer efficiency of hot electrons from gold to ITO can be analytically determined. Without the presence of the substrate, the temperature increase on the gold nanosphere induced by plasmonic absorption was calculated on the basis of thermal radiation in vacuum, which probably over-estimates the actual temperature increase in comparison to realistic experimental conditions. Here, we propose an equilibrium-thermodynamics computational method to quantify the actual efficiency of plasmon-induced electron transfer between a non-Mie-resonant metallic nanostructure and a conductive substrate and hence determine the resultant plasmoelectric potential. With a less than 2.5% relative error in predicting the steady-state temperature of a Mie-resonant nanoparticle in vacuum, and a more strict evaluation of the plasmonic local heating induced temperature increase in a single plasmonic nanostructure or an array of such structures under continuous-wave illumination (CWI), our generalized method provides a robust and accurate approach for quantifying PEP in various plasmonic-particle (array)-on-film nanocavities.
Highlights
Different from hot carriers originating from the nonradiative plasmon decay in a metal nanostructure [1, 2], the plasmoelectric potential (PEP), resulting from charge transfer between the nanostructure and a conducting substrate, exhibits the maximum where the spectral dependence of light absorption is steepest yet becomes zero at the absorption peak [3, 4]
We have developed an equilibriumthermodynamics computational method to quantify the efficiency of plasmon-induced electron transfer between a metallic nanostructure and a conductive substrate and the resultant PEP
The results obtained by our novel yet rapid and generalized method compared with that gained from the strict theoretical analysis demonstrate the high accuracy of our method to approximate the absorption cross section and the temperature increase of a charged Mie-resonant plasmonic nanostructure illuminated in vacuum, and obtain the resultant PEP
Summary
Different from hot carriers originating from the nonradiative plasmon decay in a metal nanostructure [1, 2], the PEP, resulting from charge transfer between the nanostructure and a conducting substrate, exhibits the maximum where the spectral dependence of light absorption is steepest yet becomes zero at the absorption peak [3, 4]. The early theoretical model developed by Atwater et al [3, 4] for calculating the PEP is only applicable to Mie-resonant plasmonic nanostructures where the efficiency of the hot electron transfer between the nanostructure and the substrate can be analytically determined. This limitation has restricted the use of their model to spherical or ellipsoidal Mie-resonant nanostructures. We introduce an “equivalent wavelength” method to determine the spectral dependence of absorption cross section (leading to the increase of local temperature) on the electron number of a metallic nanostructure by assuming that the absorption difference. Based on these two modifications, we have successfully predicted the electron transfer induced PEP in more general plasmonic systems under CWI, including metallic particle-on-film nanocavities, plasmonic perfect absorbers, substrate-induced Fano resonant metallic nanostructures, and surface plasmon resonant arrays on conductive substrates
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