The emission of light by polyatomic molecules in the spectral region of the second near-infrared (NIR(II)) window is severely hampered by the energy gap law, namely the quenching induced by exciton–vibration coupling. As a result, organic light-emitting diodes (OLEDs) with efficient emission wavelengths of ~1,000 nm and above are rare, despite their potential for phototherapy and bioimaging. In this study we revisit the theory of the energy gap law to quantify the contribution of each coupled vibrational mode to non-radiative transitions. The results lead us to propose two approaches that favour emission: molecular packing to extend exciton delocalization, and deuterium substitution to reduce high-frequency vibrations. We provide an experimental proof of concept by designing and synthesizing a new series of self-assembled Pt(II) complexes that exhibit high-intensity phosphorescence with peak quantum yields of (23 ± 0.3)% at approximately 1,000 nm. The corresponding OLEDs emit at a peak wavelength of 995 nm with a maximum external quantum efficiency of 4.31% and a radiance of 1.55 W sr⁻¹ m⁻², marking a substantial contribution to the development of efficient OLEDs in the NIR(II) region.

第二近红外（NIR（II））窗口的光谱区域中多原子分子的光发射受到能隙定律的严重阻碍，即激子 - 振动耦合引起的猝灭。因此，尽管有机发光二极管 (OLED) 具有光疗和生物成像方面的潜力，但其有效发射波长约为 1,000 nm 及以上的有机发光二极管 (OLED) 很少见。在这项研究中，我们重新审视能隙定律的理论，以量化每个耦合振动模式对非辐射跃迁的贡献。结果使我们提出了两种有利于发射的方法：分子堆积以扩展激子离域，氘取代以减少高频振动。我们通过设计和合成一系列新的自组装 Pt(II) 配合物来提供概念的实验证明，这些配合物在大约 1,000 nm 处表现出高强度磷光，峰值量子产率为 (23 ± 0.3)%。相应的 OLED 以 995 nm 的峰值波长发射，最大外量子效率为 4.31%，辐射率为 1.55 W sr^-1  m ^-2，标志着对 NIR(II) 区域高效 OLED 开发的重大贡献。