Performance of chlorophyll thin film as an organic photo sensor has been investigated on printed circuit board sub strates fabricated by spin coating method. Modifications of spin coating parameter-deposition were carried out in or der to obtained superior absorbance property of thin films. Experiment results showed that level absorbance increased with rising number of layer. Whereas, both rotating speed and heating post deposition dependence of absorbance were attained. Finally, switching (ON-OFF) characteristic for both under and without illumination gives a chanced for visible-range photo detector realization.