Deep-ultraviolet light-emitting diodes for frequency domain measurements of fluorescence lifetime in basic biofluorophores

We report on the development of deep-ultraviolet light-emitting diodes with AlGaN multiple-quantum-well active region for real-time fluorescence lifetime sensing in natural biofluorophores. The peak wavelengths of the devices are 340 and 280 nm, linewidth at half maximum approximately 10 nm, wall-plug efficiency up to 0.9%, output power in the milliwatt range, peak-to-background ratio up to four orders of magnitude, and cutoff frequencies for electrical modulation in the range of 100 MHz. Devices with high-frequency modulated output were demonstrated for frequency domain fluorescence lifetime measurements in basic biological autofluorophores (nicotinamide adenine dinucliotide, riboflavin, tyrosine, and tryptophan) with subnanosecond resolution.