Size distributions of chemically synthesized Ag nanocrystals

TL;DR

This study investigates the size distributions of chemically synthesized silver nanocrystals, their relation to molar ratios, and their light scattering properties in various matrices relevant for solar cell applications.

Contribution

It provides a detailed analysis of nanocrystal size distributions and their impact on light scattering, linking synthesis parameters to optical properties in different matrices.

Findings

Size distributions are approximately log-normal.

Mean nanocrystal size linearly relates to molar ratio.

Optimal molar ratios can maximize scattering at specific wavelengths.

Abstract

Silver nanocrystals made by a chemical reduction of silver salts (AgNO$_3$) by sodium borohydride (NaBH$_4$) were studied using Transmission Electron Microscopy (TEM) and light scattering simulations. For various AgNO$_3$/NaBH$_4$ molar ratios, the size distributions of the nanocrystals were found to be approximately log-normal. In addition, a linear relation was found between the mean nanocrystal size and the molar ratio. In order to relate the size distribution of Ag nanocrystals of the various molar ratios to the scattering properties of Ag nanocrystals in solar cell devices, light scattering simulations of Ag nanocrystals in Si, SiO$_2$, SiN, and Al$_2$O$_3$ matrices were carried out using Mie Plot. These light scattering spectra for the individual nanocrystal sizes were combined into light scattering spectra for the fitted size distributions. The evolution of these scattering spectra with respect to an increasing mean nanocrystal size was then studied. From these findings, it is possible to find the molar ratio for which the corresponding nanocrystal size distribution has maximum scattering at a particular wavelength in the desired matrix.