An attempt is made to study the Einstein relation for the diffusivity-mobility ratio (DMR) in nonlinear optical and
Optoelectronic compounds on the basis of a newly formulated electron energy spectrum. The results for ternary, III-V and quaternary
types of optoelectronic materials form a special case of our generalized investigation. I have also studied the DMR in II-VI, Bi, IV-VI and stressed materials on the basis of various band models as applicable for such focused materials. It has been found taking n-Cd3As2, n-CdGeAs2, n-InAs, n-InSb, n-Hg1-xCdxTe, n-In1-xGaxAsyP1-y lattice matched to InP, CdS, Bi, PbS, PbTe, PbSe and stressed InSb as
examples of the aforementioned compounds that the DMR increases with increasing electron concentration in various manners for
different band constants of the said materials and the rates of variation are totally band structure dependent. Now the well-known
results for non-degenerate wide gap optical and Optoelectronic materials have been obtained as special cases of our generalized theory under definite limiting background.