Single-LED solar simulator for amorphous Si and dye-sensitized solar cells

Abstract

An optimal combination of phosphors that simulates the solar spectrum under excitation at 365 nm has been revealed. CsVO₃ and Zn₃V₂O₈ vanadate phosphors that have broadband luminescence, Eu²⁺/Mn²⁺-doped silicates and aluminosilicates, and Fe²⁺-doped Li gallate were investigated as luminescence sources. The mixed phosphor powders had an internal quantum efficiency of 29.2%, a high color rendering index of 99, and a correlated color temperature of 5645 K. We fabricated a prototype LED solar simulator consisting of the optimized phosphor powder mixture embedded in resin on a silica glass substrate, and one high-power UV light-emitting diode (LED) with an emission wavelength of 365 nm. Our simulator achieved a Class A spectral match with the AM1.5G solar spectrum in the JIS C 8933 standard. An irradiance of 100 mW cm⁻² was measured at a forward driving current of 700 mA for the UV LED. This system functioned well as a solar simulator for solar cell testing. The I–V curves of a Si photodiode calibrated as an amorphous Si solar cell and of a TiO₂ dye-sensitized solar cell were very similar to the I–V curves measured under a conventional Xe lamp solar simulator.