Highly ordered phthalocyanine (Pc)/inorganic semiconductor heterojunctions have been created by a process of molecular beam epitaxy in ultrahigh vacuum environments (O/I- MBE). The layered metal dichalcogenides, MoS2, and SnS2, have been used as substrates, either as melt grown crystals or as thin films, created by the MBE process, immediately prior to the deposition of the organic layer. Surface electron diffraction (RHEED) is used to ascertain the type and extent of ordering of the Pc layer. Absorption or reflection spectroscopies are used in the visible wavelength region to characterize the shape and position of the Q-band absorbance of the ordered dye layers, which confirm the ordering seen by RHEED. When deposited on doped SnS2 crystals, and immersed in aqueous electrolytes, the photocurrent yield of these dye layers can also be measured, which provides an alternative means of obtaining the Q-band spectrum for ultrathin dye layers.