Persistent luminescence, long-lived emission from inorganic or organic materials after the cessation of excitation, receives considerable attention in the field of optoelectronics. Despite great achievements in the past decades, the performance of organic materials still lags behind their inorganic counterparts, which have thousands of years of history. This is largely caused by the limited understanding of the mechanisms involved in organic materials. Here we report trap-induced persistent luminescence (TIP) in organic host–guest materials, with controllable trap depths from 0.11 to 0.56 eV and tunable afterglow emission at wavelengths from 507 to 669 nm via energy level engineering. The TIP phenomenon in a typical TN@TPBi film lasts for more than 24 h, with additional energy stored at room temperature for over 1 week. It is found that the trap depth in TIP is probably determined by the energy gap between the lowest unoccupied molecular orbitals of the radical anions of the host and guest molecules, matching well with density functional theory calculations. TIP was also observed after electrical excitation, demonstrating the potential of exploiting the semiconductor features of the organic hosts. These results provide a fundamental principle to design metal-free organic emitters of persistent luminescence, thereby expanding their applications in fields such as medical delivery identification, semiconductor devices and imaging techniques.

持续发光，即停止激发后无机或有机材料的长寿命发射，在光电子领域受到相当大的关注。尽管在过去几十年中取得了巨大的成就，但有机材料的性能仍然落后于具有数千年历史的无机材料。这很大程度上是由于对有机材料所涉及的机制了解有限造成的。在这里，我们报告了有机主客体材料中的陷阱诱导持久发光（TIP），通过能级工程，陷阱深度在 0.11 至 0.56 eV 范围内可控，余辉发射波长在 507 至 669 nm 范围内可调。典型的TN@TPBi薄膜中的TIP现象可持续超过24小时，额外的能量在室温下可储存超过1周。研究发现，TIP中的陷阱深度可能由主体和客体分子自由基阴离子的最低未占据分子轨道之间的能隙决定，与密度泛函理论计算吻合良好。电激发后也观察到了 TIP，证明了利用有机主体的半导体特性的潜力。这些结果为设计持久发光的无金属有机发射器提供了基本原理，从而扩展了其在医疗输送识别、半导体器件和成像技术等领域的应用。