연구홍보포털

□ 이재현 교수 마이크로사이트: https://lab.hanbat.ac.kr/osel

 

□ 국립한밭대학교(총장 오용준)는 창의융합학과 이재현 교수가 교신저자로 참여한 공동연구 논문이 세계적인 과학기술 전문 출판사 엘스비어(Elsevier)가 발간하는 국제 저명 학술지 ‘Chemical Engineering Journal’(Impact Factor 12.5)에 온라인 공개됐다고 밝혔다.

 ○ 이번 논문은 “Negative giant surface potential engineering for suppressing exciton–polaron quenching in organic light-emitting diodes”라는 제목으로, 국립한밭대 박재용, 삼성전자 SAIT 이연경, 국립한밭대 중점연구소사업단 최영욱 연구원이 공동 제1저자로 참여했으며, 삼성전자 SAIT 김종수 박사와 국립한밭대 이재현 교수가 공동 교신저자로 참여했다.

□ 연구팀은 본 연구를 통해 OLED의 효율과 수명을 동시에 저하시키는 핵심 원인을 규명하고, 이를 제어할 수 있는 새로운 계면 설계 전략을 제시했다.

 ○ OLED 내부의 자발적 분자배향 분극(Spontaneous Orientation Polarization, SOP)으로 인해 거대 표면전위(Giant Surface Potential, GSP)가 형성되며, 이로 인해 발광층 주변에 과도한 정공이 축적되어 여기자-폴라론 소광(Exciton-Polaron Quenching, EPQ)이 발생한다.

 ○ 이러한 EPQ는 OLED의 발광 효율과 장기 신뢰성을 저하시키는 주요 원인으로 알려져 있다.

 ○ 연구팀은 음(-)의 GSP를 갖는 전자차단층(Electron Blocking Layer, EBL)을 도입해 계면 전하를 정밀하게 제어하는 새로운 OLED 설계 전략을 제안했다.

 ○ 또한, 다양한 전기·광학 분석을 통해 계면 전하 축적과 EPQ 발생 메커니즘을 체계적으로 규명했으며, 적절한 크기의 음의 GSP를 가지는 EBL은 불필요한 정공 축적을 억제해 EPQ를 감소시키고 효율과 동작 안정성을 향상시키는 반면, 지나치게 큰 음의 GSP를 가지는 EBL은 오히려 정공 주입을 과도하게 억제해 OLED 성능을 저하시킬 수 있음을 확인했다.

 ○ 이를 통해 OLED 성능 향상을 위한 최적의 GSP 설계 기준을 제시했으며, 특히 연구팀이 제안한 최적의 음의 GSP를 적용한 OLED는 기준 소자 대비 동작 수명(LT95)이 약 119.5% 향상됐으며, 효율과 동작 수명을 동시에 개선하는 성과를 보였다.

 ○ 이번 연구 결과는 OLED뿐 아니라 다양한 유기 반도체 기반 광전자소자의 계면 설계 기술에도 활용될 것으로 기대된다.

□ 이재현 교수는 “이번 연구는 OLED 내부 계면 전하 거동을 정밀하게 제어함으로써 광에너지 손실의 근본 원인인 여기자-폴라론 소광을 효과적으로 억제할 수 있음을 실험적으로 규명했다”며, “향후 다양한 유기 광전자소자의 효율과 신뢰성을 높이는 새로운 설계 전략으로 활용될 것으로 기대한다”고 밝혔다.

□ 한편, 이번 연구는 삼성전자 SAIT와 공동연구로 수행됐으며,[교육부·한국연구재단/중점연구소지원사업(2018R1A6A1A03026005); 하이브리드 3D프린팅을 이용한 액티브 인쇄전자 시스템]과 [과학기술정보통신부·한국연구재단 기초연구사업(RS-2024-00359103); 전계발광 자기공명 장치 개발을 통한 전자스핀 거동 규명과 응용]의 지원을 받았다.

 

□ Hanbat National University (President Oh Yong-jun) announced that a joint research paper in which Professor Lee Jae-hyun of the Department of Creative Convergence participated as corresponding author was published online in the internationally renowned academic journal Chemical Engineering Journal (Impact Factor 12.5), published by the world-class science and technology publisher Elsevier.

○ This paper, titled "Negative giant surface potential engineering for suppressing exciton–polaron quenching in organic light-emitting diodes," was co-first authored by Jaeyong Park of Hanbat National University, Yeongyeong Lee of Samsung Electronics SAIT, and Youngwook Choi of Hanbat National University’s Center for Key Research Projects, while Dr. Jongsu Kim of Samsung Electronics SAIT and Professor Jaehyun Lee of Hanbat National University participated as co-corresponding authors.

□ Through this study, the research team identified the key causes that simultaneously degrade OLED efficiency and lifespan, and proposed a new interface design strategy capable of controlling these factors.

○ Due to spontaneous orientation polarization (SOP) inside the OLED, a giant surface potential (GSP) is formed, causing excessive hole accumulation around the light-emitting layer and leading to exciton-polaron quenching (EPQ).

○ These EPQs are known to be a major cause of reduced OLED luminous efficiency and long-term reliability.

○ The research team proposed a new OLED design strategy that precisely controls surface charge by introducing an electron blocking layer (EBL) with negative GSP.

○ Furthermore, through various electro-optical analyses, the mechanism of interfacial charge accumulation and EPQ generation was systematically elucidated. It was found that EBLs with a negative GSP of appropriate size suppress unnecessary hole accumulation, thereby reducing EPQ and improving efficiency and operational stability, whereas EBLs with an excessively large negative GSP were found to excessively inhibit hole injection, potentially degrading OLED performance.

○ Through this, they presented optimal GSP design criteria for improving OLED performance, and notably, OLEDs using the optimal negative GSP proposed by the research team showed an operating lifetime (LT95) approximately 119.5% higher than the reference device, demonstrating simultaneous improvements in both efficiency and operating lifetime.

○ The results of this research are expected to be applied not only to OLEDs but also to interface design technologies for various organic semiconductor-based optoelectronic devices.

□ Professor Jaehyun Lee stated, "This study experimentally demonstrated that by precisely controlling the charge transport behavior at the interface inside OLEDs, it is possible to effectively suppress the plasmonization of the excimer laser-polarons, which is the fundamental cause of optical energy loss." He added, "We expect this to be used as a new design strategy to improve the efficiency and reliability of various organic optoelectronic devices in the future."

□ Meanwhile, this research was conducted in collaboration with Samsung Electronics SAIT, and received support from the Ministry of Education, the National Research Foundation of Korea / Korea Research Foundation / Priority Research Institute Support Project (2018R1A6A1A03026005); the active printed electronic system using hybrid 3D printing; and the development of an electron spin–emission magnetic resonance device through the Basic Research Program of the National Research Foundation of Korea (RS-2024-00359103); and the Ministry of Science and ICT / Korea Research Foundation Basic Research Program (RS-2024-00359103); and the development of a field emission magnetic resonance device for elucidating electron spin behavior and its application.