TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (claimed): 8 Methods for the preparation of (C1) are given e.g.(1) Process A: subjecting bromogallium phthalocyanine obtained by reacting phthalonitrile and gallium tribromide in alpha -chloronaphthalene under stirring and heating at 150-230degrees C to dry-milling and then to milling or stirring in a solvent selected from halogen-containing solvents, ketone solvents, nitrile solvents, ester solvents, alcohol solvents or ether solvents;(2) Process B: reacting chlorogallium phthalocyanine or hydroxygallium phthalocyanine with hydrobromic acid under milling or stirring;(3) Process C: subjecting bromogallium phthalocyanine obtained by reacting phthalonitrile and gallium triiodide in alpha -chloronaphthalene under stirring and heating at 150-230degrees C to dry-milling, and then to milling or stirring in an amide solvent;(4) Process D: subjecting bromogallium phthalocyanine obtained by reacting chlorogallium phthalocyanine or hydroxygallium phthalocyanine with hydrobromic acid under milling or stirring to milling in an amide solvent; and(5) Process E: subjecting bromogallium phthalocyanine obtained by reacting phthalonitrile and gallium tribromide in alpha -chloronaphthalene under stirring and heating at 150-230degrees C to dry-milling, and then to milling or stirring in an amine solvent. EXAMPLE - Phthalonitrile (41 parts), gallium tribromide (25 parts) and alpha -chloronaphthalene (200 parts) were stirred for 4 hours under heating at 200degrees C in a nitrogen atmosphere, followed by cooling to 130degrees C and filtration. The recovered solid was washed with N,N-dimethylformamide (200 parts) at 130degrees C under stirring for 2 hours, and was washed with methanol on a filter, followed by drying to recover a bromogallium phthalocyanine crystal (C') (23 parts). An aluminum substrate was coated with a solution of methoxymethylated nylon resin (5 g) and alcohol-soluble copolymer nylon (10 g) in methanol (95 g) using a wire bar and dried to form a undercoating layer. Then, crystal (C') (3 parts) was added to a solution of polyvinylbutyral (2 parts) in cyclohexanone (60 parts), and the mixture was dispersed together with glass beads (100 parts) for 3 hours in a sand mill. The resultant dispersion was further diluted with ethyl acetate (100 parts), and applied by a wire bar over the undercoating layer, followed by drying to form a charge generation layer. Then, a solution of a triarylamine compound of formula (I) (5 parts) and Z-200 (RTM: polycarbonate resin) (5 parts) in chlorobenzene (35 parts) was applied by a wire bar onto the charge generation layer and dried to form a transport layer, thus providing an electrophotographic photosensitive member, which was applied onto an aluminum cylinder to form a photosensitive drum, which was incorporated in a laser beam printer and subjected to a sensitivity measurement. Results showed that the sensitivity was 0.9 microjoules/cm2.