What are Quaternaphthalenes: New Deep-Blue Emitters?

Organic Light-Emitting Diode (OLED) displays, found in smartphones and TVs, are highly regarded for their vibrant and beautiful color reproduction. To further enhance the performance of these displays, materials that can efficiently emit a very pure blue light, known as “deep-blue,” are essential. However, finding stable and highly efficient organic materials that emit deep-blue light has been a significant challenge.

This research focuses on a new class of organic molecules called “quaternaphthalenes.” These are complex molecules formed by linking multiple naphthalene units, which are aromatic compounds (organic molecules with specific ring structures). Such molecules have the potential for their light-emitting properties to change dramatically with subtle modifications to their structure.

How Molecular “Topology” Dictates Light Emission

In chemistry, the shape of a molecule and how its atoms are connected is referred to as “topology.” This study meticulously investigated how the topology of quaternaphthalene molecules affects their “radiative dynamics” – the process from absorbing light to emitting it, essentially how they glow.

We synthesized various quaternaphthalene molecules with different topologies and thoroughly analyzed the wavelength and efficiency of the light emitted by each. The results revealed that the way the molecules are connected and their overall shape (topology) profoundly influences how efficiently and stably they can emit deep-blue light.

Contributing to Next-Generation OLED Displays

This research provides crucial insights for developing new organic light-emitting materials by designing molecular shapes to achieve desired emission colors efficiently. Deep-blue emitting materials, in particular, are one of the three primary colors (red, green, blue) in OLED displays. Improving their performance directly contributes to enhancing overall display quality and energy efficiency.

In the future, by applying this understanding of the “relationship between topology and emission properties,” we anticipate contributing to the realization of higher-performance and longer-lasting OLED displays, as well as novel light-emitting devices. Exploring the profound connection between molecular shape and function is one of the fascinations of organic chemistry, leading to the creation of new materials.

Reference Paper

• Minoru Yamaji, Kengo Suzuki, Hideki Okamoto (2026) “Synthesis and photophysical properties of quaternaphthalenes: topology-dependent radiative dynamics in deep-blue emitters” Photochemical & Photobiological Sciences. DOI: 10.1007/s43630-026-00955-4
• This research is a collaborative study with Gunma University. Corresponding author: Minoru Yamaji

Learn more about Prof. Okamoto → Synthetic and Physical Organic Chemistry Laboratory