Eight dihydrophenazine derivatives, 5-methyl-10-[methyl-, benzyl-, 3-phenylpropyl-, 9-anthrylmethyl-, 3-(9-anthryl)propyl-, 9-phenanthrylmethyl-, 2-anthrylmethyl-, and 3,5-dinitrobenzyl-]-5,10-dihydrophenazine, were employed for the study of the electron transfer in the interface of the organic two-layer diode, Au\poly(3-methyl-thiophene)\dihydrophenazines\Al, from the viewpoint of the initial process of photosynthesis. The selectivity of the electron transfer direction in the interface was evaluated by the rectification ratio (r.r.) of the dark currents of the diode under the applied potential (+2V and -2V). The dihydrophenazine AP1 with a 9-anthryl group exhibited the highest r.r. value. Two aromatic rings bridged by a methylene group with constant distance and twisted molecular plane angle of 67.7 degrees might provide an effective electron transport Au <-- PMeT <-- DP <-- Al.