The doping of nonpolymeric organic glasses with C60 is found to improve their thermal stability. Films of triphenylamine dimer (TPD) N,N′-diphenyl-N,N′-(3-methyl-phenyl)-1,1′-biphenyl-4,4′-diamine, doped with fullerene C60 and 7,7,8,8-tetracyano-quinodimethane (TCNQ) on a level between 10 and 20 mol %, were prepared using vacuum codeposition techniques. While undoped and TCNQ-doped TPD films tend to crystallize under ambient conditions, no crystallization occurs on C60-doped TPD films on minimum doping level of 15 mol %. The crystallization can be suppressed even at temperatures about 333 K, the glass transition temperature of pure TPD, if the doping level of the C60-doped TPD films reaches 20 mol %. © 1999 American Institute of Physics.