Organic semiconductor breakthrough paves way for advanced electronics

Their synthesis and characterisation of a novel molecule, ‘BNBN anthracene’, marks a pivotal moment in the development of sophisticated electronic devices.

Organic semiconductors, integral in enhancing electron movement and light properties in carbon-centric organic electronic devices, have witnessed a transformative leap thanks to this research. The team's endeavour focused on augmenting the chemical diversity of these semiconductors. This was achieved by replacing traditional carbon-carbon (C−C) bonds with boron-nitrogen (B−N) bonds, which are isoelectronic. This strategic substitution facilitates the precise modulation of electronic properties, without necessitating significant structural modifications.

The BNBN anthracene derivative, synthesised by the team, incorporates a continuous BNBN unit, derived from converting the BOBN unit at the zigzag edge. A striking feature of the BNBN anthracene, when juxtaposed with conventional anthracene derivatives (comprising solely of carbon), is the notable variations in the C−C bond length, along with a more considerable highest occupied molecular orbital–lowest unoccupied molecular orbital energy gap.

Not only does the BNBN anthracene derivative boast unique properties, but it also shows immense promise for applications in organic electronics. Utilised as the blue host in an organic light-emitting diode (OLED), the BOBN anthracene demonstrated a remarkably low driving voltage of 3.1V. This is in conjunction with enhanced efficiency in terms of current utilisation, energy efficiency, and light emission.

The team further corroborated the properties of the BNBN anthracene derivative by examining its crystal structure with an X-ray diffractometer. This analysis shed light on the structural alterations, such as changes in bonding length and angle, resulting from the boron-nitrogen (BN) bonding.

Songhua Jeong (Combined MS/Ph.D. Program of Chemistry, UNIST), the first author of the study, commented on the significance of this research, particularly in the context of anthracene, a renowned organic semiconductor. He highlighted the immense potential of the continuous BN bonding synthesised in this research for applications in organic semiconductors.

“Our study on anthracene, a type of acene widely recognised as an organic semiconductor, has laid the groundwork for future advancements in the field,” commented Songhua Jeong (Combined MS/Ph.D. Program of Chemistry, UNIST), the first author of this study. “The continuous BN bonding synthesised through this research holds great potential for applications in organic semiconductors.”

Professor Park emphasised the significance of this breakthrough, stating: “The synthesis and characterisation of compounds with continuous boron-nitrogen (BN) bonds contribute to fundamental research in chemistry. It provides a valuable tool for synthesising new compounds and controlling their electronic properties.”

This research, published online on 11th December in the journal Angewande Chemie International Edition, also features contributions from Professor Joonghan Kim’s team from the Catholic University of Korea, Professor Wonyoung Choe’s team from the Department of Chemistry at UNIST, and a research team from SFC Co., Ltd. Supported by the mid-sized research enterprise SFC and promoted by the National Research Foundation (NRF) of the Ministry of Science and ICT, under the projects of the Ministry of Trade, Industry, and Energy, this study represents a significant stride in the field of organic semiconductor research.