Chapter 5: Photoelectrical Devices

ZnO has drawn much attention for photoelectric nanodevices due to some potential advantages, including feasible preparation of single crystals, a higher electron mobility, and a larger exciton binding energy (about 60 meV compared with 25 meV for GaN). In this chapter, recent progress in ZnO-based light-emitting diodes, UV photodetectors and solar cells is summarised. A large specific surface area endows ZnO nanomaterials with abundant surface states, resulting in high internal gain of the photodetctors. Many efforts have been made to elevate the response performance of photodetectors based on ZnO nanocrystals with a diversity of morphologies. Because ZnO has similar energy band structure and larger carrier mobility to TiO₂, it has been expected to be an alternative to TiO₂ as an electrode of dye sensitized solar cells. ZnO also has great potential to be used as an effective electron transport layer for efficient perovskite solar cells.