White light-emitting diodes(W-LEDs)have attracted persistent attention in recent decades due to their magnificent advantages [1].During the development of W-LEDs,one of the major concern problems is the degradation of epoxy resins which will lead to the chromatic aberration and poor white light performance.In this context,luminescent glasses as novel durable materials,possessing excellent optical properties,flexibility of size and shape as well as epoxy resin-free in assembly process,have been explored as potential candidates for W-LEDs.However,low luminescence quantum efficiency of the glass materials often limits the overall performance as white light source.One way towards this problem relies on heavy doping activator to improve quantum efficiency of the emission process which can usually be achieved before concentration quenching of luminescence occurs [2].Amongst the activator ions proposed,Ag nanoclusters have appeared as a fascinating new class of activators for solar spectral transformation and warm-colored light source.Depending on the host material doped with Ag nanoclusters,a tuning ofAg nanoclusters emission wavelength ranging from blue-green,yellow,red and eventually to near-infrared can be achieved comparable to that of semiconductors [3].Here,we report on a white luminescence from a heavily Ag doped zinc-borateoxyfluoride glasses with surprisingly high quantum efficiency.Excited by 365 nm,the specific glass system enables highly efficient white emission for AgNO3 dopant concentration up to 12 mol%before concentration quenching is observed.This allows for the realization of high absorption cross section combined with an internal quantum efficiency of greater than 63%without further optimization of batch materials and processing conditions.In this way,the problem of luminescence quantum yield from active glass substrates in W-LEDs may be overcome.