Au/n-GaP/Al and Au/chlorophyll-a/n-GaP/Al structures were produced using n-type GaP semiconductor. A thin film layer was formed on the bright surface of the GaP semiconductor chlorophyll-a (chl-a) solution. The image of formed chl-a layer were taken by scanning electron microscope (SEM). The current voltage (I - V) measurements in dark and under illumination and capacitance-voltage (C - V) measurements in dark were taken at room temperature for the Au/n-GaP/Al and Au/ chl-a /n-GaP/Al structures. Characteristic parameters (ideality factor (IF, n), barrier height (BH) and series resistance (R-s) of these structures were calculated from ln (I) - V characteristics and Norde's functions. Similarly, for both structures, the BH, carrier concentration (N-d) in n-GaP semiconductor, diffusion potential (V-d) and Fermi energy (E-f) were calculated using C - V measurements. The photovolatic parameters of these structures were calculated from I - V measurements based on light intensity. It has been observed that chl-a thin film has changed the photovoltaic parameters of Au/n-GaP/Al structure.