Abstract: A single liquid phase formulation useful for producing an organic charge transporting film. The formulation contains: (a) a polymer having Mn at least 4,000 and comprising polymerized units of a compound of formula NAr1Ar2Ar3, wherein Ar1, Ar2 and Ar3 independently are C6-C50 aromatic substituents and at least one of Ar1, Ar2 and Ar3 contains a vinyl group attached to an aromatic ring; provided that said compound contains no arylmethoxy linkages; (b) an acid catalyst which is is an organic Bronsted acid with pKa?4; a Lewis acid comprising a positive aromatic ion and an anion which is (i) a tetraaryl borate having the formula (I) wherein R represents zero to five non-hydrogen substituents selected from D, F and CF3, (ii) BF4?, (iii) PF6?, (iv) SbF6?, (v) AsF6? or (vi) ClO4?; or a thermal acid generator.