TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compositions: Ink has total solvent capacity of greater than or equal to one quarter in which solvent is organic solvent e.g. alicyclic ketone and/or monovalent aliphatic alcohol. Alicyclic ketone is cyclohexanone. Monovalent aliphatic alcohol is monovalent alicyclic alcohol with 5-8 carbon atoms. Preparation (Disclosed): Aromatic diiodonium salt is obtained by preparing benzene intermediate compound, dissolving intermediate compound in methanol, adding ion-exchange water to methanol solution, heating intermediate body solution, dripping borate-ethyl ether complex to intermediate body solution, reacting, performing crystallization and suction filtration, washing crystal with ion-exchange water, and drying under reduced pressure.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: Charge transporting compound is low molecular weight compound e.g. crosslinked polymer or non-crosslinked polymer. Ink contains charge transporting compound. Preferred Definitions:    Ar1=paraphenylene;    Ar2=Ph;    Ar3=para-tert.-butylphenyl; and    Ar21-Ar24=pentafluorophenyl.    SPECIFIC COMPOUNDS - 1 Compound (1) is disclosed e.g. (4-(phenyliodonio)phenyl)(4-tert.-butylphenyl)iodonium-bistetrakis(pentafluorophenyl)borate.    EXAMPLE - Intermediate compound 1-((4-tert.-butylphenyl)((trifluoromethanesulfonyl) oxy)iodo)-4-(phenyl((trifluoromethanesulfonyl)oxy)iodo)benzene was prepared. Intermediate compound (0.3 g) was dissolved in methanol (3 ml) in argon atmosphere, ion-exchange water (3 ml) was added to methanol solution, and intermediate body solution was heated at 50 degrees C. Lithium tetrakis(pentafluorophenyl) borate ethyl ether complex (0.89 g) was dissolved in ion-exchange water, solution was made to react at 50 degrees C for 1 hour, obtained solution was dripped to intermediate body solution, and resulting solution was stirred. Crystallization was performed, suction filtration was carried out, recovered crystal was washed with ion-exchange water and dried under reduced pressure at 50 degrees C, and (4-(phenyliodonio)phenyl)(4-tert.-butylphenyl)iodonium-bistetrakis(pentafluorophenyl)borate was obtained as white crystal (0.66 g, 97.2% yield).