Modeling Spectra of Low-Power SMD LEDs as a Function of Ambient Temperature

The information of spectral changes with various parameters is a key for optimizing the performance and thus improving long-term reliability of light-emitting diodes (LEDs) in solid-state lighting applications. In this paper, the extension of spectrum model was used to estimate the spectral flux of indium gallium aluminum phosphide (InGaAlP)-based low-power surface-mounted device (SMD) LEDs. The spectra and photometric parameters of LED packages were measured at several ambient temperatures to test the spectrum model extension. The spectrum model is constructed at 298 K to predict the spectral fluxes of the LED at any ambient temperature. Carrier temperature, peak frequency, and bandgap energy variations with ambient temperature are included in this extension. The agreement between the measured and theoretical results of spectrum, luminous flux, and International Commission on Illumination (CIE) color coordinates validates the extended spectral model for low-power LEDs.