Jinnai Kazuya, Kabe Ryota, Lin Zesen, Adachi Chihaya
Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Fukuoka, Japan.
JST, ERATO Adachi Molecular Exciton Engineering Project, Fukuoka, Japan.
Nat Mater. 2022 Mar;21(3):338-344. doi: 10.1038/s41563-021-01150-9. Epub 2021 Nov 29.
Organic long-persistent-luminescent (OLPL) materials demonstrating hour-long photoluminescence have practical advantages in applications owing to their flexible design and easy processability. However, the energy absorbed in these materials is typically stored in an intermediate charge-separated state that is unstable when exposed to oxygen, thus preventing persistent luminescence in air unless oxygen penetration is suppressed through crystallization. Moreover, OLPL materials usually require ultraviolet excitation. Here we overcome such limitations and demonstrate amorphous OLPL systems that can be excited by radiation up to 600 nm and exhibit persistent luminescence in air. By adding cationic photoredox catalysts as electron-accepting dopants in a neutral electron-donor host, stable charge-separated states are generated by hole diffusion in these blends. Furthermore, the addition of hole-trapping molecules extends the photoluminescence lifetime. By using a p-type host less reactive to oxygen and tuning the donor-acceptor energy gap, our amorphous blends exhibit persistent luminescence stimulated by visible light even in air, expanding the applicability of OLPL materials.
具有长达数小时光致发光的有机长余辉发光（OLPL）材料，因其灵活的设计和易于加工的特性，在应用中具有实际优势。然而，这些材料中吸收的能量通常存储在中间电荷分离态，当暴露于氧气时该状态不稳定，因此除非通过结晶抑制氧气渗透，否则会阻止在空气中的持续发光。此外，OLPL材料通常需要紫外光激发。在此，我们克服了这些限制，展示了非晶态OLPL体系，该体系可被高达600nm的辐射激发，并在空气中表现出持续发光。通过在中性电子供体主体中添加阳离子光氧化还原催化剂作为电子接受掺杂剂，在这些共混物中通过空穴扩散产生稳定的电荷分离态。此外，添加空穴捕获分子延长了光致发光寿命。通过使用对氧气反应性较低的p型主体并调节供体-受体能隙，我们的非晶态共混物即使在空气中也能表现出由可见光激发的持续发光，扩展了OLPL材料的适用性。
