透過轉印技術實現近紅外光有機發光二極體性能突破：機制、材料與元件探討

Abstract

近年來近紅外光有機發光二極體被廣泛討論，而此類元件在能量間隔定律的限制下無法達到高效率。本研究致力於利用介面能量轉移來提升有機發光二極體元件表現。 本研究將轉印技術引入近紅外光有機發光二極體元件的製備。透過將近紅外螢光染料 BTP-eC9 轉印於 Pt(II) 錯合物的薄膜上達到介面能量轉移的效果。 BTP-eC9 為放光在 740 奈米的磷光材料，而 Pt(II) 錯合物為放光大於 900 奈米的螢光材料。在使用轉印技術的雙層結構中，可以觀察出 Pt(II) 錯合物放出的磷光，有效地進行三重態到單重態的能量轉移至 BTP-eC9，並在放光位置大於 900 奈米有高強度螢光。我們最後得到放光在 925 奈米的元件，並達到外部電子效率 2.24%(1.94 ± 0.18%)，並在亮度上達到39.97 W sr−1 m−2。表面型態鑑定、元件及光譜分析也被用來證明其能量轉移的機制。總結而言，透過轉印技術達成能量轉移來製備有機發光二極體元件，將可以被廣泛應用並提供螢光 OLED 發展的前景。

In recent years, near-infrared organic light-emitting diodes (NIR OLEDs) have gained considerable attention; however, these devices face efficiency limitations due to the energy gap law. This study aims to enhance OLED device performance through interfacial energy transfer. A transfer printing technique was introduced in the fabrication of NIR OLEDs. By imprinting the NIR fluorescent dye BTP-eC9 onto a thin film of Pt(II) complex, effective interfacial energy transfer was achieved. BTP-eC9 is a phosphorescent material with emission at 740 nm, while the Pt(II) complex emits fluorescence at wavelengths above 900 nm. In the dual-layer architecture enabled by transfer printing, phosphorescence from the Pt(II) complex effectively undergoes triplet-to-singlet energy transfer to BTP-eC9, resulting in high-intensity fluorescence beyond 900 nm. Ultimately, the device emitted at 925 nm, achieving an external quantum efficiency (EQE) of 2.24% (1.94 ± 0.18%) and a peak radiance of 39.97 W sr−1 m−2. Surface morphology, device analysis, and spectroscopic studies confirmed the energy transfer mechanism. In summary, this energy-transfer approach via transfer printing provides a promising outlook for the development of hyperfluorescent OLEDs in the NIR region.