Highly efficient green-emitting ZnO:Cu phosphors for NUV-pumped white-emitting diodes

• Published in: Dalton transactions : an international journal of inorganic chemistry 2023-09, Vol.52 (36), p.1274-12716
• Main Authors: Tran, Manh Trung, Quang Trung, Do, Tri Tuan, Nguyen, Tuan, Nguyen Trong, Tu, Nguyen, Van Du, Nguyen, Duy Hung, Nguyen, Van Quang, Nguyen, Thi Hao Tam, Tong, Trung Kien, Nguyen Duc, Hieu, Nguyen Minh, Huy, Pham Thanh
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d3dt01663c

Phosphor-converted white light-emitting diodes (WLEDs) have received significant attention; however, the leaked light from their blue InGaN chips has an undesirable effect on human health. Hence, it is necessary to develop red, green, and blue-emitting phosphors, which can be excited by an NUV chip instead of a blue chip. Herein, green-emitting ZnO:Cu 2+ phosphors have been successfully synthesized by a simple and facile thermal diffusion method. The obtained powder shows a broad emission band peaking at 525 nm and a strong absorption peak at 377 nm. The ZnO:5%Cu 2+ phosphor annealed at 800 °C in 2 hours revealed a lifetime of 0.57 ms, an activation energy of 0.212 eV, and the highest emission intensity with ( x , y ) CIE colour coordinates (0.3130, 0.5253). A WLED prototype has been fabricated by coating the ZnO:5%Cu 2+ phosphor on an NUV 375 nm LED chip, where this coated phosphor shows a high quantum efficiency (QE) of 56.6%. This is, so far, the highest reported QE value for ZnO-based phosphors. These results suggest that the ZnO:Cu 2+ phosphor could be an excellent candidate for NUV-pumped phosphor-converted WLED applications. A WLED prototype obtained by applying efficient green ZnO:Cu 2+ phosphors, made via thermal diffusion, onto near-ultraviolet light source.