Researchers develop ultra-high efficiency perovskite LEDs by strengthening lattice
The research findings were published in the journal Nature Communications on July 24. The team was led by Professor Tae-Woo Lee from the Department of Materials Science and Engineering at Seoul National University, in collaboration with Professor Andrew M. Rappe of the University of Pennsylvania,
Perovskite is a semiconductor material composed of cube-shaped nanocrystals consisting of organic cations, metal cations, and halogen elements. Perovskite light emitters have garnered attention as promising next-generation emitters due to their excellent color purity, tunability, and cost-effectiveness.
However, prior to 2014, perovskites were primarily used in solar cells, as their luminescence was not bright enough to be visible at room temperature. Despite this limitation, Professor Lee recognized the potential of perovskite as a next-generation emitter early on and secured a portfolio of fundamental patents for perovskite light-emitting materials in 2014.
Additionally, in 2015, his team published the first research paper demonstrating the enhancement of the efficiency in perovskite LED from a mere 0.1% to 8.53%, comparable to the level of phosphorescent OLEDs. This achievement has inspired researchers worldwide to conduct intensive and in-depth research on improving the efficiency of perovskite emitters.
Professor Lee's team further advanced perovskite self-emissive devices in 2022, achieving an external quantum efficiency (EQE) of 28.9% (nearly theoretically achievable maximum), peak brightness of 470,000 nits, and an operational lifetime of up to 30,000 hours. Moving towards commercialization, Professor Lee's startup company, SN Display Co. Ltd., showcased TV and tablet display prototypes at the CES (Consumer Electronics Show) in 2022 and 2023, making a great appeal to industry insiders.
However, the research team realized the need to address a key challenge: the reduction in luminescence efficiency due to the inherent ionic nature of the perovskite. Unlike traditional inorganic semiconductors, perovskite materials are composed of weak ionic bonds, and large-amplitude displacement of the atoms in their crystal lattices can cause dynamic disorder. This dynamic disorder interferes with the radiative recombination process in perovskite materials, leading to exciton dissociation and reduced luminescence efficiency.
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