Analytical model for the I-V characteristics of fresh and degraded commercial LEDs

An analytical model for the conduction characteristics of commercially available light-emitting diodes (LED) subjected to severe degradation conditions is reported. The devices were stressed at different temperatures in the range from 27°C to 80°C using high-current (80mA) accelerated life-tests. First, a modified compact model for the fresh I-V characteristic of the devices is presented. Instead of two parallel diodes with a single series resistance as frequently considered, our proposal consists in two parallel diodes with independent series resistances. In this way, the I-V characteristic can be expressed as a closed-form solution in terms of the Lambert W function. Second, it is shown that, thanks to its flexibility, this alternative approach can be applied to model I-V curves of severely damaged LEDs as well.