Could a magnetic field be used to identify in advance which OLEDs will keep smartphone and TV screens bright the longest? A KAIST research team has developed a technique that predicts OLED lifetime by analyzing small changes in brightness caused by a magnetic field. The technique reduces the need for long operating tests and is expected to support the development of longer-lasting displays.

KAIST (President Choongsik Bae) announced on October 22 that a research team led by Professor Seunghyup Yoo of the School of Electrical Engineering has developed a method that predicts the lifetime of blue phosphorescent OLEDs from changes in their brightness under a magnetic field. The study was conducted jointly with Professor Jang Hyuk Kwon’s team at Kyung Hee University, Professor Jae-Hyun Lee’s team at Hanbat National University, and researchers at ASTA Inc.

OLEDs are devices that emit light on their own when an electric current flows through them, and they are used in smartphone and TV screens. A screen produces a wide range of colors by combining red, green, and blue light. The blue phosphorescent OLED examined in this study uses electrical energy efficiently to emit blue light. Achieving a long lifetime while maintaining high efficiency is a key challenge in its development.

Conventionally, determining how long an OLED will last has required operating it for tens to hundreds of hours while monitoring the decrease in brightness. This process takes a long time, and the device’s performance also degrades during testing.

The research team focused on the phenomenon in which a magnetic field slightly changes the brightness of an OLED. Inside an OLED, light is produced when electrically charged particles meet and recombine, and a magnetic field can affect this process.

The researchers operated OLEDs at a constant current and precisely measured changes in brightness while varying the magnetic field strength with an electromagnet. In this experiment, the OLEDs became slightly brighter under the magnetic field. This change contains several different responses. The team separated the component most closely related to lifetime degradation and converted it into a single evaluation metric.

The team applied this metric to four types of blue phosphorescent OLEDs that were made with the same light-emitting material but had different internal structures. Devices that showed a smaller brightness response to the magnetic field from the start maintained their initial luminance longer in long-term operating tests. This indicates that the brightness response to a magnetic field can serve as an indicator of OLED lifetime.

The magnetic field was not used to extend OLED lifetime. Instead, the researchers measured how OLEDs respond to a magnetic field to identify in advance which devices will last longer. By measuring and analyzing brightness changes too small to see with the naked eye, the team obtained a basis for estimating how long a device will operate.

The team also investigated why this response occurs. Over long periods of use, bonds in the organic molecules inside an OLED can break and form defects that interfere with light emission. Through molecular simulations and analysis, the researchers explained that these defects can affect the light-emitting process and that this effect can be reflected in the brightness response to a magnetic field.

Display companies and research institutes can use this technique when developing new OLEDs. For example, when several prototypes with different internal structures are made from the same light-emitting material, early measurements can identify the structures most likely to last longer, so that further development can focus on them. Because not every prototype needs to be operated for a long time before results are available, the method is expected to help reduce development time and cost.

However, further validation is needed before this relationship can be applied to a wider range of OLEDs. When the materials or internal structure change, the main factors that respond to a magnetic field can also change, so each type of device requires its own analysis.

“This result can be used to quickly select materials and device structures with long lifetimes in the early stages of OLED development,” said Professor Seunghyup Yoo. He added that, with further validation under various conditions, the method is expected to support the development of high-efficiency, long-lifetime blue OLEDs and to be used as a non-destructive evaluation technique.

Dr. Jeoungmin Ji of KAIST led the study as first author, and Professor Seunghyup Yoo served as corresponding author. The results were published online in Nature Communications on September 30.

Paper title: Magnetic Electroluminescent response as a predictive indicator of operational lifetime in phosphorescent blue OLEDs
DOI: 10.1038/s41467-026-78180-x

This research was supported by the Technology Innovation Program (20020408, Development of direct analytic methods for exciton dynamics in OLEDs and lifetime-enhancing technologies based thereon) funded by the Ministry of Trade, Industry and Resource (Korea).