Natural dyes in hybrid chalcogenide multi-layer thin films

Abstract

New highly photoconductive hybrid multi-layer semiconductors have been developed, comprising cathodically electrodeposited CdSe or $${\hbox {Zn}}_{x} {\hbox {Cd}}_{1-x} \hbox {Se}$$ thin films and natural photosynthetic pigments, isolated from spinach. A layer of the organic dye, Chlorophyll $$\alpha $$ or Carotenes, is either deposited by spin coating technique over an inorganic thin film (two-layer structures) or ‘sandwiched’ between two inorganic semiconductive films (three-layer structures). X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, diffused reflectance spectroscopy and photoelectrochemical studies are employed, in order to fully characterize the received products. In the case of the three-layer hybrids, a significantly enhanced photo-response is observed, leading up to 300% improved photoelectrochemical efficiency values, compared to that of the pure inorganic films. This amelioration, stemming from the synergetic action of hybrids’ components, is more prominent in the case of $${\hbox {Zn}}_{x} {\hbox {Cd}}_{1-x} \hbox {Se}$$ systems, where a significant amount of Cd has been substituted by Zn: therefore, Zn are considered environmentally friendlier alternatives to pure CdSe-based semiconductors.