Watt-level High Power InGaN-based Blue LED Photometric,Chromatric and Electric Characteristics

Watt-level high power InGaN-based blue LEDs were packaged using a traditional packaging method,and their luminous flux,electric power,luminous efficiency,emission spectra and chromaticity coordinates were measured under different forward current(IF)from 50 to 1 000 mA,with a current interval of 50 mA.The results showed that the luminous flux rises sub-linearly,but the luminous efficiency declines with the increase of IF.When the temperature rises with the increase of drive current,the carrier kinetic energy enhances,and then more non-equilibrium electrons diffuse out of the quantum wells,which could result in the decrease of luminous efficiency.The spectrum morphologies and the peak wavelength λp shows a slight blue-shift with the increase of IF from 50 mA to 450 mA,which is related to the influence of In ingredient and the leveled band-gap at a proper high current.The blue-shift values are different between different blue LEDs.However,when IF increases from 500 mA to 800 mA,λp shows a slow red-shift due to the temperature dependence of band-gap energy,and the electron-hole pair recombination luminescence mechanism.In addition,full width at half maximum(FWHM)of the InGaN-based blue LED emission spectra is widened,and the reason was analyzed by the model of configuration coordinate.Moreover,the chromaticity coordinate x,y also changes at the same time.Photometric,chromatric and electric characteristics of blue LEDs make important contributions to chip manufacture and the high power white light LEDs,especially,to the high color rendering warm white LEDs.