Hierarchical ZnO nano-tree growth for high efficiency solar cell

Abstract

Increased surface area is the key to high efficiency solar cell. Nature inspired "nanoforest" of high density, long branched "treelike" multi-generation hierarchical ZnO nanowire photoanodes grown via a simple selective hierarchical growth approach was proven to boost the dye sensitized solar cell efficiency. The efficiency increase is due to greatly enhanced surface area for higher dye loading and light harvesting, and also due to reduced charge recombination by providing direct conduction pathways along the crystalline ZnO "nano-tree" multi generation branches. We performed parametric study how hierarchical ZnO nanowire structure can be effectively grown to yield optimum hierarchical ZnO nanowire photoanode through the combination of length-wise growth and branched growth.