Energy transfer mediated single-component white light emission in a novel Bi3+/Eu3+ co-doped Sr2Ga2GeO7 phosphor for white LEDs

Abstract

To fulfill the escalating demand for high-quality white lighting, the exploration of novel and advanced luminescent materials holds a significant role in addressing the issues of reabsorption, color bleaching and deviation in modern WLED solid-state lighting technology based on phosphor-converted materials. In this research, a series of novel Bi³⁺-activated gallium-germanate luminescent materials Sr₂Ga₂GeO₇ (SGGO): Bi³⁺ were synthesized by means of the classic high-temperature solid-phase method. A comprehensive exploration of their crystal structure, electronic structure, and optical transition properties were conducted through a combined experimental and theoretical calculation analysis. The research outcomes suggest that Bi³⁺, which is prone to occupying Sr sites, shows a remarkable blue emission with a peak at approximately 450 nm throughout the entire spectral range from near ultraviolet (UV) to near infrared when excited at 315 nm, and this is attributed to the ³P₁→¹S₀ transition. Additionally, by devising an efficient energy transfer strategy from Bi³⁺ to Eu³⁺, single-component white light can be attained by merely adjusting the doping concentration of Eu³⁺ in the SGGO: Bi³⁺, Eu³⁺ co-activation system. Eventually, devices packaged based on 310 nm ultraviolet chips also demonstrate the potential application of the synthesized material in WLEDs. These findings contribute to a deeper understanding of the luminescence and energy transfer mechanisms of Bi³⁺-activated systems, and also offer essential guidance for the advancement of high-performance Bi³⁺-doped advanced light-conversion materials and effective materials for various applications demanding enhanced light conversion properties.