Novel color tunable phosphors NaYGeO 4 : Tm 3+ , Tb 3+ , Eu 3+ for ultraviolet excited white LEDs with good thermal stab
- PDF / 3,080,452 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 2 Downloads / 182 Views
Novel color tunable phosphors N aYGeO4: Tm3+, Tb3+, Eu3+ for ultraviolet excited white LEDs with good thermal stability Wenyu Zhao1 · Xiaoyan Feng1 · Bin Fan1 Received: 17 March 2020 / Accepted: 12 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Single-phased phosphors NaYGeO4: Eu3+, Tb3+, Tm3+ were synthesized by a high temperature solid-state reaction. Upon the excitation of 300–325 nm, the NaYGeO4: Eu3+, Tb3+, Tm3+ phosphors emit combining blue, green and red lights, coming from the characteristic emissions of T m3+, Tb3+, Eu3+, respectively. Mechanisms of concentration quenching and 3+ 3+ energy transfer from Tb to Eu have been investigated. The emission color can be adjusted by tuning the doping contents appropriately. The optimal NaYGeO4: 0.12Eu3+, 0.07Tb3+, 0.03Tm3+ phosphor emits a warm white light with chromaticity coordinate of (0.3521, 0.3761), correlated color temperature of 4842 K, activation energy for thermal quenching effect of 0.213–0.225 eV and internal quantum efficiency of 40.2%. The obtained properties indicate that NaYGeO4: Eu3+, Tb3+, Tm3+ phosphor might be a promising single-phased white light emitting phosphor for UV-pumped white-LED.
1 Introduction Nowadays, white light emitting diodes (w-LEDs) have been widely used in the display and lighting markets due to their merits of energy saving, high energy efficiency, compact size, low power consumption, environmental friendliness and long lifetime [1–3]. The traditional method for manufacturing w-LEDs is sealing yellow phosphor YAG:Ce on a blue LED chip (eg. InGaN) with organic resin [4]. Unfortunately, these w-LEDs not only have poor color rendering index (Ra
Data Loading...
