Novel photo-functional naphthalenedithiol (NpDDT) as a linker molecule for formation of EuS nanocrystal assembles (EuS nano-assembles) has been reported. NpDDT is synthesized by the reaction of 1,4-dihydroxynaphthalene with 1,10-decanedithiol in benzene at 80 degrees C for 1hour. Formation of EuS nano-assembles with NpDDT is observed by TEM measurement. Photophysical properties of EuS nano-assembles with NpDDT are characterized using the emission spectra and the emission quantum yields. The emission quantum yields of naphthalene units in NpDDT are depended on the aggregation size of EuS nano-assembles. Novel luminescent NpDDT has been reported as an effective linker material for formation and observation of semiconductor EuS nano-assembles for the first time.