Solar Filtering Applications of Indium Tin Oxide Nanoparticles in Heat Transfer Fluids

We investigated the use of indium tin oxide (ITO), a semiconductor nanoparticle, as a spectral filter for use in concentrated GaAs photovoltaic (PV) cells. The synthesized nanoparticles filter high energy UV and infrared photons that usually degrade PV performances. The energy of the absorbed solar radiation will be transferred to a heat transfer fluid for photothermal energy conversion. Synthesis of ITO nanoparticles tailored to achieve optimal optical performance while remaining stable in a heat transfer fluid is ncessary. Particles were synthesized using a one-pot synthesis with indium acetylacetonate (In(acac) 3 , tin bis (acetylacetonate) dichloride (Sn(acac) 2 Cl 2 ) , and myristic acid (CH#8323; (CH#8322;)#8321;#8322;COOH) as the starting materials and oleylamine as a reducing agent and surface passivation ligand. In order to enhance the solubility and stability of the as-synthesized ITO particles in heat transfer fluids, different strategies such as ligand exchange, silica encapsulation, and synthesis with alternate passivating ligands were employed. Characterization of the nanoparticles was accomplished by Fourier transform infrared spectroscopy, UV-Visible spectrometry, dynamic light scattering, scanning electron microscopy, and solution stability tests at various temperatures.