A joint team from Seoul National University, led by Prof. Lee Tae-woo, and the University of Cambridge, led by Prof. Samuel Stranks, has demonstrated a new thermodynamically guided vacuum-deposition process for perovskite light-emitting diodes (PeLEDs), aimed at next-generation display applications.
Patterns and array perovskite light-emitting devices on a 7 cm by 7 cm large-area substrate. Image credit: Seoul National University College of Engineering
Vapor deposition is attractive for industry because it is compatible with existing OLED infrastructure and scalable to large areas, but conventional perovskite vapor growth has been limited by kinetically driven crystallization, which produces mixed-dimensional phases, nanoscale heterogeneity, broadened energy landscapes and ultimately lower device efficiencies.
To address this, the researchers designed an X-type quasi-two-dimensional perovskite emitter of the form (CsPbBr3)𝑛−1Cs2PbBr2X2. During in situ vapour deposition, they introduce an organic spacer molecule that substitutes halide sites and covalently binds to Pb²⁺, steering the crystallization toward specific quasi-2D phases with high phase purity instead of a disordered mixture. This chemical design provides thermodynamic control over the crystallization process, allowing the most energetically favorable luminescent structure to form uniformly across the film, rather than relying on uncontrolled kinetic growth.
The team further improves structural control by forming a self-assembled hetero-scaffold from LiF and the spacer molecule at the interface. This scaffold acts as a nanoscale growth template that promotes spatially uniform nucleation and suppresses phase segregation. Structural and spectroscopic analyses show dimensionally and spatially homogeneous films with high photoluminescence quantum yield above 85%, reduced trap densities and efficient exciton confinement, leading to narrow-band emission with high color purity.
Devices based on these X-type quasi-2D vapor-deposited films achieve an external quantum efficiency of 21.9%, an electroluminescence linewidth of 78.5 meV and an operational stability exceeding 1,500 minutes of continuous operation. The authors also demonstrate scalable pixel arrays and confirm compatibility with large-area and flexible substrates and patterning platforms, underscoring the relevance of this approach for practical display manufacturing.
In comments accompanying the work, Prof. Lee notes that such technology could become a core foundation for ultra-high-resolution displays and microdisplays for AR and VR, leveraging vacuum deposition processes already established in the OLED industry.
