Al Amin Nurul Ridho, Lin Ming-Jun, Wang Jui-Ming, Yang Zu-Po, Su Hai-Ching, Chang Chih-Hao
Department of Electrical Engineering, Yuan Ze University, Taoyuan 32003, Taiwan.
Institute of Photonic System, National Yang Ming Chiao Tung University, Tainan 71150, Taiwan.
ACS Appl Mater Interfaces. 2025 Jul 16;17(28):40881-40892. doi: 10.1021/acsami.5c08869. Epub 2025 Jul 7.
Leveraging conventional red-emitting materials, a color-tuning strategy is used to develop high-performance near-infrared (NIR) organic light-emitting diodes (OLEDs). This study presents a practical approach for achieving color-tunable optically impaired OLEDs through localized surface plasmon resonance (LSPR), which extends the emission of red-emitting materials into the NIR region, thereby eliminating the need for dedicated NIR emitters. The method utilizes silver (Ag) and gold (Au) nanoparticle-based anodes modified with titanium dioxide (TiO) coatings under various rapid thermal annealing (RTA) treatments (200 °C, 400 °C, and 600 °C). Three TiO coating techniques─overcoating, stacking, and sandwiching─were compared in terms of their influence on the LSPR behavior and electroluminescence (EL) spectra. UV-vis spectroscopy, including transmittance and absorbance analyses, confirmed that the different coating methods facilitated LSPR formation and thus modulated EL characteristics and induced distinct spectral features. Ag nanoparticles exhibited stronger LSPR responses and greater color-tunability than Au nanoparticles. Scanning electron microscopy revealed that RTA promoted island-like nanoparticle growth and minimized agglomeration, while TiO coatings enhanced island formation, resulting in well-defined and narrower absorbance peaks. The overcoating approach successfully red-shifted the primary emission peak of red phosphorescent OLEDs from 663 to 723 nm, achieving a maximum external quantum efficiency of 12.91% and a low turn-on voltage () of 2.41 V. Furthermore, a broad EL emission spectrum (full width at half maximum = 199 nm) spanning 643-842 nm was achieved using the TiO stacking configuration. These findings highlight the potential of Ag nanoparticle-based anodes for color-tunable NIR OLEDs and introduce a stacking coating technique with potential for broad-wavelength applications.
利用传统的红色发光材料，采用颜色调谐策略来开发高性能近红外（NIR）有机发光二极管（OLED）。本研究提出了一种通过局域表面等离子体共振（LSPR）实现颜色可调的光学受损OLED的实用方法，该方法将红色发光材料的发射扩展到近红外区域，从而无需专门的近红外发射体。该方法利用在各种快速热退火（RTA）处理（200℃、400℃和600℃）下用二氧化钛（TiO）涂层改性的基于银（Ag）和金（Au）纳米颗粒的阳极。比较了三种TiO涂层技术——包覆、堆叠和夹层——对LSPR行为和电致发光（EL）光谱的影响。紫外可见光谱，包括透射率和吸光度分析，证实不同的涂层方法促进了LSPR的形成，从而调节了EL特性并诱导出不同的光谱特征。Ag纳米颗粒比Au纳米颗粒表现出更强的LSPR响应和更大的颜色可调性。扫描电子显微镜显示，RTA促进了岛状纳米颗粒的生长并使团聚最小化，而TiO涂层增强了岛的形成，导致吸光度峰明确且变窄。包覆方法成功地将红色磷光OLED的主要发射峰从663nm红移至723nm，实现了12.91%的最大外量子效率和2.41V的低开启电压（）。此外，使用TiO堆叠结构实现了跨越643 - 842nm的宽EL发射光谱（半高宽 = 199nm）。这些发现突出了基于Ag纳米颗粒的阳极在颜色可调近红外OLED方面的潜力，并引入了一种具有宽波长应用潜力的堆叠涂层技术。
