Taku Sawaki

Wavelength conversion film (WCF) for crystalline silicon PV modules

We describe wavelength conversion film (WCF) specially designed for improving efficiency in crystalline silicon photovoltaic (c-Si PV) modules, which use the ultraviolet region of the sunlight spectra for use in Europium (Eu) complexes as photoluminescence (PL) materials. We developed methodologies for dispersing PL materials and evaluated the effects of WCF with regards to the differences in short circuit current densities between the cells and modules (▵J<inf>sc</inf>). We confirmed that ▵J<inf>sc</inf> = 0.5 mA/cm² in an in-house testing with an artificial light source (solar simulator). In a field test with commercially available encapsulant, increases in the open circuit voltage (V<inf>oc</inf>), not only in increases in ▵J<inf>sc</inf> were also confirmed for the WCF modules. We also conducted the evaluations and obtained ▵J<inf>sc</inf> =0.63 mA/cm² for WCF using a newly designed Eu complex.