Alternating Current‐Driven Oxide Powder Electroluminescent Device Employing Vertically Aligned ZnO Nanowire Array

A novel type of AC‐driven oxide powder electroluminescent (EL) device is demonstrated. The device is based on stable heterogeneous junctions between Mn 2+ ‐activated zinc germanate (Zn 2 GeO 4 :Mn) oxide phosphor and a vertically aligned ZnO nanowire array. The ZnO nanowire array is synthesized on an ITO‐coated glass substrate via a hydrothermal growth method. A stable phosphor–nanowire junction is formed by simple drop‐coating of a Zn 2 GeO 4 :Mn oxide phosphor suspension on the nanowire layer followed by annealing at 400 °C for 3 h. Bright green light (≈20 cd m −2 ) with a wavelength of 535 nm from the as‐fabricated EL device is observed, and the as‐fabricated device shows excellent stability in air, maintaining a brightness of ≈10 cd m −2 for 15 days with less than 2.5% intensity loss. The electroluminescence emission mechanism is discussed in detail. This new and facile strategy to build an oxide powder EL device can enable cost‐effective, highly stable, and energy‐efficient devices for lighting or display applications.