Photoinduced energy transfer in ZnO–tetraphenylporphyrin systems

The optical absorption and photoluminescence measurements were carried out for ZnO nanoparticle–tetraphenylporphyrin (TPP) systems made of four kinds of TPP’s with and without p-aminophenyl groups. The ZnO particles were treated with l-cysteine in order to make a ZnO–(l-cysteine)–TPP binding. However, this binding was not formed because of an absence of the ZnO–(l-cysteine) binding. In the case of metal-free TPP’s, the central hydrogen atoms of the TPP ring were replaced by a Zn atom during an aging of 2–4 weeks. An energy transfer from photoexcited ZnO to TPP occurs by a collision between ZnO and TPP in the dispersed medium.