Nearfield Scanning Optical Microscopy Characterization Of Arrays Of Rare Earth Based Nanocrystals

Rare earth based nanocrystals are of great interest due to their unique photoluminescent characteristic of upconversion; absorption of near infrared radiation then emission of visible photons. Therefore, these materials provide excellent resolution for increasing the efficiency of solar cells by utilizing the 20% infrared and near infrared radiation of the sun. Using a home-constructed nearfield scanning optical microscope (NSOM), we studied the size, geometry, and surface functionality in correlation with the photoluminescent spectra of individual NaYF4:Yb,Er nanocrystals and arrays of NaYF4:Yb,Er nanocrystals generated by particle lithography. In contrast to prior aperture and apertureless NSOM, our new design exploits the photoluminescence of Si3N4 atomic force microscopy tips under laser excitation to delineate between near-field and far-field signals. These initial investigations provide new insights into the structure-spectroscopy relationship of engineered rare earth nanomaterials to guide the optimization of these nanomaterials in photovoltaic applications.