Ohmic contacts for both holes and electrons were formed on naphthalene tetracarboxylic anhydride films (NTCDA) at Pt-doped p-type film/metal and Na-doped n-type film/metal junctions, respectively. The injection current density reached 4Acm(-2) at a low bias field of 6 x 10(4) V cm(-1). Pt was revealed to be a candidate for a permanent dopant that can act as an electron acceptor in the formation of p-type organic semiconductors.