In this study, metal/Zn-complex/semiconductor (MPS) Schottky photodiodes are fabricated. Interface layer is deposited using a metal-nicotinate/nicotinamide mixed ligand [Zn(C6H6N2O)2(C6H4NO2)2(H2O)]⋅1/2(H2O) complex synthesized with Zn dopant. Different film layers are obtained by dissolving 0.5, 1.0, 2.0, and 3.0 mg Zn-complex in 1 mg spin-coating solution. Thermal analysis techniques are performed between room temperature and 900 °C to study the thermal behavior of the complex as a metal oxide. The surface morphology of the polymeric film layers is investigated by microscopy methods, and the results show relatively smooth and compact surface characteristics for all Zn-complex mass contributions. To evaluate electrical properties of the fabricated device, current–voltage, capacitance–voltage and conductance–voltage measurements are performed under dark and illumination intensities between 20 and 100 mW/cm2 depending on Zn-complex mass at the interface. These measurements indicate light sensitivity of the diodes. In addition, transient characteristics are investigated at these illumination intensities to evaluate photoresponse behaviors. Then, the highest photoconductivity is recorded for 3 mg Zn-complex. The experimental results indicate that the diodes exhibit good photosensitive behavior, and they can be used for opto-electronic applications.