High-binding-energy material achieves record QLED efficiency and lifetime

A research team has developed a new material that can considerably improve the lifespan and efficiency of quantum electroluminescent diodes (QLED), which is a new generation display technology. The application of a high -energy bonding organic material, which is resistant to degradation under electrical and thermal constraint, to the holes transport layer (HTL) should contribute to the development of new generation QLED which can maintain brightness and stability over prolonged periods.

The study is published in the journal Little. The team was led by Professor Youngu Lee in the Department of Energy and Engineering Sciences at DGIST.

The Qled drew attention as a new generation displays thanks to their bright colors and their exceptional energy efficiency. However, the HTL material based on commonly used triphenylamine has limits, because its molecular structure is vulnerable to electrical stress, which means that the efficiency of the device is quickly deteriorating over time and causing a short lifespan. Although various attempts were made to solve this problem, they were often faced with a dilemma in which the mobility of the holes and the blocking capacity of the electrons were simultaneously degraded.

To overcome these limits, Professor Lee’s team has developed a new organic HTL material incorporating the stable molecular structure of “Dibenzofuran”. This material considerably increases intramolecular binding energy and improves the mobility of holes while reducing electronic back leak and surface defects, thus improving both the efficiency and stability of QLED.

The team used this material to obtain high external quantum efficiency (EQE) of 25.7% in the qled green devices. In addition, the lifespan of the device (T₅₀ at 100 CD M⁻²) reached approximately 1.46 million hours, 66 times longer than conventional devices, demonstrating long -term stability. This represents the highest performance among the materials based on the same class (triarylamine) reported to date.

Professor Lee of the DGIST Energy and Engineering Department of Energy and Engineering said: “We have overcome the limits of conventional materials with low molecular links and developed a stable HTL which has considerably improved the efficiency and lifespan of QLED. To move forward, we will continue to apply high energy materials.