Harnessing solar energy can be as simple as tuning the optical and electronic properties of metal oxides at the atomic level by making an artificial crystal or super-lattice ‘sandwich.’ "Metal oxides can be tailored to meet all sorts of needs, which is good news for technological applications, specifically in energy generation and flat screen displays,” said Louis Piper, assistant professor of physics at Binghamton University.
Though metal oxides are very good at electron conduction, they are very poor “hole” conductors. Holes refer to absence of electrons, and can conduct positive charge. To maximize their technologically potential, especially for artificial photosynthesis and invisible electronics, hole conducting metal oxides are required.
Layered metal oxides systems can be combined to selectively ‘dope’ (replace a small number of one type of atom in the material), or ’tune’ (control the size of the band gap). Recent work revealed that a super-lattice of two hole-conducting copper oxides could cover the entire solar spectrum. The goal is to improve the performance while using environmentally benign and cheap metal alternatives.
Indium oxide is one of the most widely used oxides used in the production of coatings for flat screen displays and solar cells. It can conduct electrons really well and is transparent. But it is also rare and very expensive. Piper’s current research is aimed towards using much cheaper tin oxide layers to get electron and hole conduction with optical transparency.
Piper is convinced that the development of new and exciting types of metal oxides that can be tailored for specific applications are well within our reach. “We’re talking battery storage, fuel cells, touch screen technology and all types of computer switches,” said Piper.