New perovskite emitter boosts vapor-deposited LEDs efficiency

Seoul National University College of Engineering announced that a joint research team led by Professor Tae-Woo Lee of the Department of Materials Science and Engineering at SNU and Professor Samuel D. Stranks of the University of Cambridge has developed a vapor-deposited perovskite light-emitting diode (PeLED) with world-leading efficiency. The team achieved this by discovering a new X-type perovskite emitter capable of thermodynamically stabilizing a luminescence-favorable phase during the vacuum deposition process.

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Perovskites have attracted significant attention as next-generation display materials because of their high efficiency, vivid color emission and compatibility with existing OLED fabrication processes, enabling implementation without large-scale facility investments. However, in conventional vacuum deposition processes, crystallization is not thermodynamically controlled, leading to rapid and nonuniform crystal growth.

To address this issue, the research team introduced X-type spacer organic molecules to design a new X-type quasi-two-dimensional perovskite emitter, enabling thermodynamically controlled crystal growth on the substrate and the formation of a uniform emissive phase favorable for high-efficiency light emission. In addition, the team developed a hetero-scaffold that promotes selective crystal-phase growth, providing a strategy for precise crystallization control in vacuum deposition. As a result, the team realized PeLEDs with both high emission efficiency and high color purity.

The findings were published July 1 in Nature Nanotechnology.

Why vacuum deposition has lagged

Perovskites (typically with a three-dimensional ABX₃ structure, where A is a cation, B is a metal cation and X is a halide anion) are emerging as promising next-generation display materials because of their high color purity, excellent emission efficiency, low material cost and compatibility with vacuum deposition processes—unlike conventional quantum dots. However, high efficiency alone is insufficient for industrial applications. Large-area production, uniform thin-film formation, precise thickness control and pixel patterning must all align with existing display manufacturing processes.

Currently, vacuum deposition is widely used in OLED production. If perovskites can be fabricated using this method, compatibility with existing infrastructure would significantly enhance commercialization potential.

However, perovskite vacuum deposition involves complex simultaneous reactions of multiple precursors on the substrate to form crystals. When this process becomes too rapid and complicated, multiple crystal phases can form, resulting in nonuniform films with reduced emission efficiency and color purity.

Thus, beyond simple process optimization, a new material design strategy capable of controlling the formation pathway of perovskite crystals is essential for commercialization.

X-type molecules guide crystal growth

To overcome these challenges, the team developed a novel X-type quasi-two-dimensional perovskite emitter distinct from conventional quasi-2D structures through vacuum deposition. This represents a new material and fabrication strategy for achieving highly uniform, high-efficiency PeLEDs with high color purity.

The team introduced X-type spacer molecules, which strongly coordinate with central lead ions during crystallization, suppressing disordered crystal growth and promoting the selective formation of the most energetically stable crystal phase. This enabled the development of a thermodynamic phase stabilization strategy that directs the formation of the desired phase during deposition.

Additionally, the team developed a nanoscale hetero-scaffold by chemically bonding X-type spacer molecules with lithium fluoride (LiF). This structure prevents random crystal growth of perovskites and promotes uniform crystallization across the film.

Performance gains and display potential

Through this approach, the team achieved perovskite thin films with a photoluminescence quantum yield (PLQY) exceeding 85%. The resulting PeLEDs exhibited an external quantum efficiency (EQE) of 21.9% and a narrow emission linewidth of 16.8 nm, demonstrating both high efficiency and excellent color purity—representing world-leading performance among vapor-deposited PeLEDs.

The team also confirmed that these PeLEDs can be fabricated on large-area substrates, flexible platforms and patterned structures, highlighting their applicability to real-world display manufacturing.

This study provides a new direction for the commercialization of perovskite displays by resolving a key challenge in vapor deposition—lack of thermodynamic phase control during film growth—and enabling uniform fabrication of highly efficient emitters with high color purity.

In particular, the X-type quasi-2D perovskite developed in this work represents a fundamentally new material design strategy that controls the crystallization process itself, rather than a simple additive approach. This strategy addresses major limitations of conventional vacuum deposition, including film nonuniformity, low color purity and phase mixing.

The findings hold significant industrial implications. Given that vacuum deposition is already a core process in OLED manufacturing, this technology offers high compatibility with existing infrastructure, reducing capital investment compared with transitions such as LCD to OLED. Furthermore, the technology enables high efficiency even at ultra-small pixel sizes, making it suitable for ultra-high-resolution displays, AR/VR microdisplays, next-generation color-conversion layers and emissive devices.

Lee stated, "This study is significant because it provides a fundamental understanding of how perovskite precursors react and crystallize on a substrate during vacuum deposition and, based on this understanding, establishes a new X-type quasi-2D perovskite emitter design. By realizing perovskite light-emitting devices with world-leading efficiency and color purity through a vacuum-deposition process compatible with existing OLED manufacturing infrastructure, this work is expected to provide a key technological foundation for accelerating the practical implementation of ultra-high-resolution displays and AR/VR microdisplays."

The research team plans to further expand the scalability and patterning capabilities of vapor-deposited PeLEDs, aiming to accelerate the development of next-generation display technologies.

More information: Chan-Yul Park et al, Halide-site-substituting spacer creates quasi-two-dimensional perovskites for vapour-deposited light-emitting diodes, Nature Nanotechnology (2026). DOI: 10.1038/s41565-026-02208-y

Provided by Seoul National University