‘Zero modification’ emission layer can achieve high-performance perovskite LEDs

Researchers have shown that even without altering the perovskite emissive layer, incorporating polycaprolactone-silver nanoparticles (PCL@AgNPs-P) as an emission gain layer can significantly enhance the luminance and external quantum efficiency (EQE) of perovskite light-emitting diodes (PeLEDs).

Their findings are published in the journal Materials Horizons.

This innovative approach utilizes Förster resonance energy transfer (FRET) and the Purcell effect, paving the way for high-efficiency PeLEDs and advancements in laser optics applications.

PeLEDs have garnered significant attention recently due to their outstanding optoelectronic properties. However, conventional methods to improve PeLED efficiency typically require chemical modifications to the perovskite emissive layer, such as doping or structural tuning. These approaches often compromise manufacturing stability and increase production costs.

This study demonstrates that even without modifying the perovskite emissive layer, adding a PCL@AgNPs-P emission gain layer can significantly enhance PeLED efficiency. This innovative approach not only simplifies the fabrication process but also preserves the purity and stability of the perovskite emissive layer, offering more excellent practical value.

The research team utilized microwave-assisted post-addition technology to create a symbiotic emission gain layer of polycaprolactone and silver nanoparticles. This emission gain layer improves PeLED performance through two key mechanisms.

The emission gain layer absorbs energy from low-dimensional perovskite (minor phase) and transfers it to high-dimensional perovskite (major phase), thus increasing the radiative intensity of the major phase perovskite.

Boosting the Purcell effect

The emission gain layer with silver nanoparticles forms a cavity-like optical structure, which enhances the spontaneous emission rate and further improves the electroluminescence (EL) intensity.

The results indicate that, compared to PeLEDs lacking an emission gain layer, PeLEDs that incorporate PCL@AgNPs-P as an emission gain layer achieved a luminance of 11,320 cd/m² and an external quantum efficiency (EQE) of 15.5%. Moreover, they maintained stable green emission purity and a narrow emission spectrum (94 meV) across various operating currents.

The research was led by Dr. Ru-Jong Jeng from the Institute of Polymer Science and Engineering at National Taiwan University, along with Dr. Chi-Ching Kuo from the Institute of Organic and Polymeric Materials at National Taipei University of Technology.

“This technology effectively enhances PeLED efficiency and stability without altering the perovskite emissive layer, moving away from the conventional dependence on perovskite modification-based methods for efficiency improvement,” said Prof. Ru-Jong Jeng.

“It has significant potential for applications in high-performance display technologies, optical communication, laser optics, and quantum photonics, providing a straightforward fabrication process, excellent performance, and strong industrialization potential for next-generation PeLED designs.”