Lin Zesen, Ye Jinting, Shinohara Shin, Tanaka Yuya, Yoshioka Rengo, Chan Chin-Yiu, Lee Yi-Ting, Tang Xun, Mitrofanov Kirill, Wang Kai, Ouchi Hayato, Moshniaha Liliia, Narayana Yemineni S L V, Ishii Hisao, Zhang Xiao-Hong, Adachi Chihaya, Chen Xian-Kai, Kabe Ryota
Organic Optoelectronics Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa, 904-0495, Japan.
Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 1, Singapore, 117585, Singapore.
Nat Commun. 2025 Mar 19;16(1):2686. doi: 10.1038/s41467-025-58048-2.
Long-persistent luminescence (LPL) materials have applications from safety signage to bioimaging; however, existing organic LPL (OLPL) systems do not align with human scotopic vision, which is sensitive to blue light. We present a strategy to blueshift the emissions in binary OLPL systems by upconverting the charge-transfer (CT) to a locally excited (LE) singlet state. Through rigorous steady-state and time-resolved photoluminescence spectroscopy and wavelength-resolved thermoluminescence measurements, we provide the direct experimental evidence for this upconversion in OLPL systems featuring small energy offsets between the lowest-energy CT and LE singlet states. These systems exhibited strong room temperature LPL, particularly when extrinsic electron traps are added. Importantly, the developed OLPL system achieved Class A (ISO 17398) LPL, matching well with human scotopic vision. The findings not only elucidate the role of small energy offsets in modulating LPL but also provide potential avenues for enhancing the efficiency and applicability of OLPL materials.
长余辉发光（LPL）材料在安全标识到生物成像等领域都有应用；然而，现有的有机LPL（OLPL）系统与对蓝光敏感的人类暗视觉不匹配。我们提出了一种策略，通过将电荷转移（CT）上转换为局域激发（LE）单重态，使二元OLPL系统中的发射发生蓝移。通过严格的稳态和时间分辨光致发光光谱以及波长分辨热释光测量，我们为最低能量CT和LE单重态之间能量偏移较小的OLPL系统中的这种上转换提供了直接的实验证据。这些系统在室温下表现出强烈的LPL，特别是当添加外在电子陷阱时。重要的是，所开发的OLPL系统实现了A类（ISO 17398）LPL，与人类暗视觉匹配良好。这些发现不仅阐明了小能量偏移在调节LPL中的作用，还为提高OLPL材料的效率和适用性提供了潜在途径。
