By Akshatha ChandrashekarReviewed by Frances BriggsOct 21 2025Growing films with a new dual-laser film technique results in defect-free perovskite layers. The result is brighter, longer-lasting LEDs for electronics; think longer battery life and more vibrant screen tech.
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A new laser-based fabrication method has significantly improved the quality of cesium lead bromide (CsPbBr3) thin films. Published in Science and Technology of Advanced Materials, the study showcases a dual-laser vacuum process that enables precise control over film growth and interfaces, resulting in bright green electroluminescence and promising device performance.
Perovskites are widely studied for optoelectronic devices because of their tunable properties and natural defect tolerance. However, traditional solution-processing methods often introduce impurities and structural defects, limiting their performance and durability.
To address this, a research team has developed a dry, vacuum-based approach that combines pulsed laser deposition with infrared molecular beam epitaxy (IR-MBE). This setup allows simultaneous deposition and in situ thermal control within a single chamber, critical for achieving high-purity, uniform films.
Design and Performance
Using a single-crystal CsPbBr3 target, the team applied a pulsed UV Nd:YAG laser (266 nm, 10 Hz) to ablate material onto sapphire (α-Al2O3) substrates under ultra-high vacuum. A continuous-wave IR laser was used to heat the substrate during deposition, maintaining a controlled temperature that minimizes cesium loss. Thin films were grown at various temperatures, with 200 °C identified as the optimal point for achieving high crystallinity and balanced stoichiometry.
X-ray diffraction analysis confirmed that the films grown at 200°C displayed the sharpest peaks and narrowest rocking curve widths, indicating superior crystalline structure. Elemental analysis showed the Cs/Pb ratio approached 0.9 at this temperature, close to the ideal composition.
When grown above 200°C, the films showed cesium deficiency due to increased evaporation, which led to structural degradation. Below this temperature, incomplete crystallization limited optical performance. At temperatures above 250°C, film deposition failed entirely due to severe cesium loss, highlighting the narrow window for stable CsPbBr3 formation.
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Optical measurements revealed a direct bandgap of 2.36 eV with a strong excitonic absorption feature near 2.4 eV. Films grown at 200 °C emitted bright green light with a peak at 524 nm and showed a photoluminescence intensity nearly 100 times higher than films grown at suboptimal temperatures.
Time-resolved photoluminescence indicated an exciton emission lifetime of 7.2 nanoseconds, while time-resolved microwave conductivity (TRMC) showed a carrier lifetime of 16.5 microseconds and an effective mobility of 2.47 cm2/V·s, on par with bulk single crystals.
These high-quality films were then integrated into a multilayer LED device composed of ITO, Mg0.3Zn0.7O, CsPbBr3, α-NPD, MoOx, and a gold electrode. The device emitted bright, uniform green electroluminescence with a narrow spectral width of 16.5 nm and a turn-on voltage of approximately 2.3 volts, consistent with the measured bandgap.
The researchers noted that while small amounts of Cs4PbBr6, a phase known for strong luminescence, were detected, the dominant emission behavior could be attributed to the CsPbBr3 layer. In contrast to films grown using IR-MBE alone, the pulsed laser deposition approach effectively suppressed the formation of CsPb2Br5, an unwanted Cs-deficient impurity phase that can degrade optical performance.
Repeated fabrication trials confirmed the reproducibility of film quality and device performance.
Where Could this Take LEDs?
A key advantage of this dual-laser system lies in its ability to precisely grow both inorganic and organic layers within the same vacuum environment, reducing contamination risks and ensuring clean interfaces. This level of process control is essential for enhancing charge injection, reducing recombination losses, and improving overall stability in perovskite-based devices.
The study demonstrates dual laser ablation as a highly controllable fabrication method for perovskite optoelectronics, meeting long-standing challenges related to film uniformity, impurity control, and structural coherence. The researchers suggest that future work should explore device longevity, heterointerface engineering, and integration with new materials to widen the application of this technique beyond LEDs.
Journal Reference
Kumagai, R., et al. (2025). Laser ablation process of CsPbBr3 heterostructures for light-emitting diode applications. Science and Technology of Advanced Materials. DOI: 10.1080/14686996.2025.2554045 https://www.tandfonline.com/doi/full/10.1080/14686996.2025.2554045
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