Absorption is the underlying reason for the change of luminescence traits. And the lifetime influences on the absorption in turn. That is a common law

it is not only suitable for photoluminescence

but also other types of luminescence. In field of electroluminescence

there are two kinds of luminescence center blue have dramatically dissimilar lifetime

in the co-doped ZnS:Cu

Mn material. The experiment clearly demonstrates that the ratio of luminance of Cu and Mn change with the driving frequency. This law is also fit for the change of luminance in Cu

which has blue and green luminescent centers. The experiment proves that this law has something to do with lifetime and nothing to do with the way of exciting and the reasons is abruptly quenching. No matter what quenching is

the lifetime of centers must be shortened

for shorter lifetimes centers the inten-sity increases with the increase of driving frequency more quickly. The luminescence of singlet and triplet states in organic electroluminescence is crucial in determining the overall efficiencies. The density of states in singlet and triplet levels is 1:3. The transition from triplet state to singlet state is generally forbidden. People considered that the luminescence efficiency is limited to 1/4. But they ignored that their lifetimes are quite different

and this situation influences on the efficiency of luminescence. So the efficiency of luminescence in organic electroluminescence may be greater than 25%. The experiment also demonstrates the correctness of relationship between the differential cross-section and lifetime which was brought forward in thin film electroluminescence. In the case of thin film electroluminescence the differential cross-section of excitation is inversely proportional to the lifetime center. This result provides the basis of fabricating color tunable display panel using a single phosphor material. The rate of absorption of luminescent materials is controllable by luminescence lifetime

and the effect influences on the brightness and apparent efficiency of luminescence.