ZnO−TiO<sub>2</sub> Core−Shell Nanorod/P3HT Solar Cells

We evaluate an ordered organic−inorganic solar cell architecture based on ZnO−TiO<sub>2</sub> core−shell nanorod arrays encased in the hole-conducting polymer P3HT. Thin shells of TiO<sub>2</sub> grown on the ZnO nanorods by atomic layer deposition significantly increase the voltage and fill factor relative to devices without shells. We find that the core−shell cells must be exposed to air to reproducibly attain efficiencies higher than 0.05%. Cells stored in air for 1 month are 0.29% efficient.