Researchers from Yonsei University, collaborating with LG Display, have uncovered the mechanism behind magnesium fluoride’s exceptional performance as a hole-injection layer (HIL) in OLED devices. While LG Display has already deployed this material in WOLED TV panels for improved emission, the exact reasons for the enhancement remained unclear—until now.
Magnesium fluoride is classically viewed as an insulating material, which would suggest it should be a weak HIL. The new findings reveal a surprising interaction: when magnesium fluoride is combined with organic semiconductors, it actively draws electrons from the organic molecules. In fact, electron transfer occurs spontaneously as soon as the two materials are brought together, even without any external stimulation.
The study shows that magnesium fluoride can boost the population of positive charge carriers by up to 50 times when mixed with organic molecules. This surge in hole transport facilitates smoother charge flow, contributing to more efficient OLED emission.
An additional key insight is that the magnesium fluoride–organic material mixture does not crystallize into its usual crystal structure. Instead, it transitions into a glassy, disordered amorphous state. This structural change lowers the energy barrier typically encountered when combining different materials, which further enhances efficiency, particularly at lower operating voltages.
Source: OLED-Info, December 15, 2025, by Ron Mertens
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