An efficient luminescence conversion LED for white light emission, fabricated using a commercial InGaN LED and a 1,8-naphthalimide derivative

A highly efficient luminescence conversion light emitting diode (LUCO LED) was fabricated, using a commercial InGaN LED (460 nm) and 4-N,N-diphenyl-9-(4-tert-butylphenyl)-1,8-naphthalimide (DBN), dispersed in epoxy as the primary light source and LUCO material, respectively. The emission of very bright white light was observed at 20 mA, with CIE chromaticity coordinates of (0.32, 0.33) and conversion efficiency of 82%. The luminescent output of the LUCO LED decreased rapidly, but when the LUCO LED was prepared using DNB dispersed in poly(methyl methacrylate), it only decreased to about 67% of the initial value after 19 days of continual operation at 200 mA.