Utilization of down-shifting photoluminescent ZnO quantum dots on solar cells

We report on the synthesis of photo luminescent zinc oxide (ZnO) quantum dots, their deployment on the window side of photovoltaic structures and the measured influence on the power conversion efficiency. Down-shifting effects were characterized by exciting the synthesized nanostructures with photons in the 340-350 nm range, and measuring the wavelength of the emitted photons observed to be similar to 500 nm. The colloidal ZnO quantum dots were synthesized in an ethanol-based solution, obtaining different sized nanostructures centered at 4 nm, optically recognizable by their emission in various colors. Subsequently, different concentrations of zinc oxide quantum dots were prepared and dispersed in poly-methyl-methacrylate (PMMA) to be spin cast on the window side of previously characterized solar cells. The observations made to date indicate an improvement of similar to 4.8% in the PCE. In this work, we discuss the results obtained and suggest pathways to further increase the power conversion efficiency of photovoltaic devices employing quantum dots.