Charge injection and storage in thin films of chlorophyll a

Abstract

Chlorophyll a microcrystals can be electroplated from a suspension in an organic solvent. The optical‐absorption spectra of the resulting films indicate an interaction between the porphyrin rings of different molecules. It is shown that these films can store electronic charge. The charge storage was studied by plating the chlorophyll on silicon and using the well‐known C (V) technique. It is also shown that monomeric films, made by heating the microcrystalline films at about 100 °C, have different charge‐storage properties. The charge‐injection and charge‐storage properties of the chlorophyll films are discussed in terms of the molecular arrangement of the films. The results are also compared with ac‐ and dc‐conductivity measurements of the films.