Electrophotographic elements having charge transport layers containing high mobility polyester binders

An electrophotographic element comprising a high mobility charge-transport layer. The layer binder is a polyester according to formula I: wherein Ar represents phenylene, terephthoyl, isophthoyl, 5-t-butyl-1,3-phenylene and phenylene indane; D represents alkyl, linear or branched, or cycloalkyl, having from 4 to about 12 carbons; R , R , R , and R represent H, alkyl having 1 to 4 carbon atoms, cyclohexyl, norbornyl, phenylindanyl, perfluoralkyl having 1 to 4 carbon atoms, alpha , alpha -dihydrofluoroalkyl having 1 to 4 carbon atoms, and alpha , alpha , omega -hydrofluoroalkyl having 1 to 4 carbon atoms; and R , R , R , R , R , R , R , and R represent, H, halo ad alkyl having from 1 to about 6 carbons; x is from 0 to 0.8; and y is from 0 to 1.n