Multicolour LED in luminescence sensing application

Light emitting diodes (LEDs) are in general used as light sources with nearly monochromatic spectral characteristic. Beyond this typical application, they can work as light sensing devices. In this case, their spectral response has the property of an optical band pass filter. As an application we present a sensor for the measurement of environmental properties like temperature and pressure based on the temperature and oxygen dependent luminescence decay of some luminescence materials. Herein, a multicolour LED is used as a compact excitation and detection system. Furthermore, we have investigated the spectral absorption characteristics and the responsivity of standard LEDs working as light detectors and compared them with photodiode based detectors.