Biomimetic Synthesis of ZnO Thin Films

Biomimetic reaction systems, where small proteins and peptides assist in the growth of inorganic materials, has the potential for making complex structures that are otherwise difficult to achieve. Living organisms use a peptide-inorganic matrix to control the morphology of the inorganic structures. Using this method as inspiration we sought a similar approach for novel materials. Zinc oxide as chosen as the target material due to its many exciting optoelectrical properties. Phage display was performed on ZnO sample and used to identify small peptides with high binding affinity for ZnO. By means of an aqueous based synthesis, these high affinity peptides were added at various concentrations to the solution so growth of the ZnO crystals could occur in the presence of the peptides. In the absence of peptides, the ZnO grows with a long needlelike morphology. When peptides are added to the growth solution they are found to dramatically alter the final morphology of the ZnO substrates. By altering the concentrations of these peptides, the morphology of ZnO nanorods can be controlled, ultimately allowing for the formation of thin films. Through the use of these peptides, we form ZnO thin films on a variety of substrates including glass and flexible PET plastic.