Synonyms: [1,1'-Biphenyl]-4,4'-diamine,N,N'-di-1-naphthalenyl-N,N'-diphenyl- (9CI);4,4'-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl;4,4'-Bis[phenyl(naphthalen-1-yl)amino]-1,1'-biphenyl;N,N'-Biphenyl-N,N'-bis(1-naphthyl)[1,1'-biphenyl]-4,4'-diamine;N,N'-Biphenyl-N,N'-bis-(1-naphthenyl)-[1,1'-biphenyl]-4,4'-diamine;N,N'-Bis(naphthalen-1-yl)-N,N'-diphenylbenzidine;N,N'-Bis(a-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine;N,N'-Di(1-naphthyl)-N,N'-diphenyl-4,4'-diaminobiphenyl;N,N'-Di(naphthalen-1-yl)-N,N'-diphenylbenzidine;N,N'-Di-1-naphthyl-N,N'-diphenylbenzidine;N,N'-Diphenyl-N,N'-bis(a-naphthyl)-1,1'-biphenyl-4,4'-diamine;NPB;NPB (photoreceptor);ST16/7;a-NPD;