Design, synthesis and characterization of photoluminescent species based on ln(iii) ions. Study of its efficiency in improving the performance of photovoltaic devices

Abstract

Several complexes that produce luminescence through the down-shifting mechanism have been studied as potential candidates for improving photovoltaic devices for several years. Specifically, complexes formed by lanthanide (III) ions and chromophoric ligands such as 1,10-phenanthroline have been of great interest. In this thesis, these types of complexes were chosen due to the wide variety of chromophoric ligands available in the market, the scientific interest in lanthanide ions due to their unique properties, and the need to continue improving in the field of renewable energies that currently exists in the society. With this in mind, new luminescent complexes were designed and synthesized from Eu(III), Tb(III), Gd(III), Yb(III), and Er(III) ions. Some derivatives of 1,10-phenanthroline such as 5-methyl-1,10-phenanthroline or 2,3-pyrazine-1,10-phenanthroline were chosen as ligands, along with ß-diketonates as counterions and to complete the coordination sphere of the lanthanides. Synthetic routes were designed to become increasingly simple, avoiding the use of high temperatures and large reaction times. By changing water, typically used as a solvent in the synthesis of these types of complexes, to ethanol, the reaction time was reduced from 8 to 2 hours, and very pure complexes were obtained with yields of around 90%. The use of different bridging ligands, such as benzoate, allowed the production of new bimetallic complexes with the overall formula [M1M2 (bz)4(phen)2(tta)2], where M1 and M2 can be different lanthanides (III). The combination of Eu(III), Tb(III), and Gd(III) in this type of complex yielded very interesting results, with very intense photoluminescence that improved a polycrystalline silicon minimodule by up to 0.52 percentage points. Stability studies against ultraviolet radiation were also carried out to determine the degradation rate of the complexes once laminated onto a silicon minimodule. It was found that after 2000 hours of study in a climate chamber and after having received 450,000 Wh/m2 of radiation, the efficiency improvement of the minimodule caused by the luminescent complexes had not decreased, making this type of complex a very promising option for improving the efficiency of photovoltaic panels in the near future.