Abstract
We elaborate a semi-analytical model for calculation of the bulk internal emission of photoelectrons from metal nanoparticles into a semiconductor matrix. We introduce important effects in the model as the jump of the effective electron mass at the metal–semiconductor interface and cooling of the hot electrons because of electron–electron and electron–nanoparticle surface collisions in the metal. We study the interplay between the plasmonic electric dipole and quadrupole resonances and reveal the optimum parameters for different geometrical shapes of nanoparticles with respect to the photoemission cross section. We find that the absorption cross section well-predicts the optimum size of the dipolar nanoparticle. This opens the possibility for the fast optimization and design of the photoelectric devices.
Highlights
Generation of hot electrons in plasmonic nanoantennas, that is, in nanometer-sized metal particles, with subsequent emission of the hot electrons into the surrounding semiconductor matrix attracts growing interest because of its potential applications in photochemistry and photocatalysis, light harvesting, and optoelectronics.[1−5]Resonant electron photoemission from nanoantennas occurs under the excitation of “localized surface plasmon resonances” (LSPR) of collective oscillations of the electron density in metal nanoantennas by external quasi-monochromatic electromagnetic field with a carrier frequency equal to LSPR frequency
We have developed the theoretical model and computational tool for calculation of the bulk photoemission cross section (PCS) into the semiconductor matrix
The model takes into account several features that cannot be neglected for adequate computation of the bulk photoemission, namely the jump of the photoelectron effective mass at the nanoparticle− matrix interface, cooling of the hot photoelectrons due to electron−electron collisions, and modification of the dielectric constant of the nanoparticle metal owing to the collisions of photoelectrons with the nanoparticle boundary
Summary
Generation of hot electrons in plasmonic nanoantennas, that is, in nanometer-sized metal particles, with subsequent emission of the hot electrons into the surrounding semiconductor matrix attracts growing interest because of its potential applications in photochemistry and photocatalysis, light harvesting (solar cells and nano-photodetectors), and optoelectronics.[1−5]. Note that LSPR in large nanoparticles can be broadened because of the radiative losses,[6] whereas in small nanoantennas the resonance is broadened because of electron collisions with nanoparticle boundary.[7,8] It is well-known that the surface and volume photoelectric effects can occur in plasmonic nanoantennas.[3,9] Surface photoelectric effect is characterized by absorption of photons by electrons at their collision with the interface between the nanoparticle and the surrounding medium. The Journal of Physical Chemistry C photoemission” in ref 12) can be enhanced substantially by special resonant states at the metal−semiconductor interface These results are very important for further development of the surface photoeffect and nanoantennas as sources of hot electrons, but their consideration is outside of the scope of present paper. The results and the outlook for further research are discussed in Conclusions
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