The group’s work was inspired by hierarchical multi-generation branching in trees, which allows the plants to maximize the capture of sunlight. By developing a simple hydrothermal approach combined with polymer removal and seed deposition, the scientists were able to synthesize ZnO nanowires (NWs) that resembled tiny trees with long branches (see image).

In the study, the researchers found that the short-circuit current density and the overall light conversion efficiency were almost four times higher for DSSCs fabricated with branched ZnO NWs compared with devices based on vertically grown ZnO NWs. The efficiency increase is attributed to the increase in surface area for higher dye loading and light harvesting and also to reduced charge recombination through direct conduction along the crystalline ZnO branches.

The hierarchical nano-tree structures will be also useful for high-capacity energy storage and high-efficiency energy consumption devices.

More details can be found in the journal Nanotechnology.