Soongsil University researchers develop new material to boost PeLED efficiency and lifespan

A joint research team from Soongsil University has developed a novel polymer material designed to significantly improve the performance of perovskite light-emitting diodes (PeLEDs). The breakthrough, achieved by Professor Kang Beom-gu of the Department of Chemical Engineering and Professor Park Min-ho of the Department of Materials Science and Engineering, addresses key limitations in current PeLED technology.

The new material functions as a hole transport layer (HTL), a critical component situated between the hole injection layer and the emissive layer in PeLEDs. The HTL's role is to efficiently transport "holes" to the emissive layer, balancing them with electrons to produce light. The efficiency and operational lifespan of a PeLED are heavily dependent on the quality of this layer. The research team precisely synthesized a polymer using anionic polymerization, incorporating triphenylamine groups known for their hole-transporting properties.

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This research is meaningful in that it synthesized hole-transporting polymers with controlled molecular weight and molecular weight distribution through precise anionic polymerization, simultaneously improving the hole transport properties and emissive layer interface properties of PeLEDs.

This advanced polymer exhibits excellent thermal stability and solvent resistance, making it suitable for solution-processed PeLED manufacturing. When applied as the HTL, PeLEDs incorporating the new polymer showed a lower hole injection barrier and improved hole transport characteristics compared to those using conventional materials like Poly(9-vinylcarbazole) (PVK). This resulted in a substantial increase in external quantum efficiency (EQE) and current efficiency, with one device achieving an EQE of 15.8% and a lifespan approximately 12 times longer than PVK-based devices.

Researchers attribute these performance gains to enhanced hole transport properties, optimized energy level alignment, and the stabilization of perovskite emissive layer interfaces by the triphenylamine structure. This interface stabilization effectively suppresses non-radiative recombination, a common issue that reduces light emission efficiency. The findings, published in the European Polymer Journal, represent a significant step towards developing high-performance, stable next-generation lighting and display devices.

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In the future, we plan to focus on developing materials for high-efficiency and high-stability next-generation light-emitting devices by more precisely controlling the molecular structure and energy levels of hole-transporting polymers.