Materials with multi-photon absorption (MPA) feature, are highly desirable for applications such as deep-seated tumor treatment, high spatiotemporal resolution bioimaging, sophisticated micro-nano fabrication, optical data storage, frequency-upconverting laser, and optical limiting. The classical two-photon absorption (TPA) process relies on an extremely short-lived virtue state, leading to the requirement of an ultrahigh power density of femtosecond pulsed laser. To break this application barrier, the key solution is to extending the lifetime of the transition state in TPA. Recently, the operation of TPA with low-power non-coherent excitation (LPNC-TPA) was achieved by leveraging the mono-reduced species (such as radical anion) and the triplet excited state of dye molecules as the transition state with a relatively long lifetime. In this review, the mechanism of these LPNC-TPA processes will first be introduced, followed by the approaches to extend the lifetime of the mono-reduced species and the triplet state. Then, considering its ability to tune the aggregation mode of dye molecules, the metal–organic framework (MOF) will be emphasized as an efficient tool to operate efficient LPNC-TPA in the solid state. The merits and features of LPNC-TPA materials will be revealed through their emerging applications in photoredox catalysis, photopolymerization, 3D printing, in vivo cancer treatment, bioimaging, and biosensing. Finally, the future directions and challenges of LPNC-TPA are proposed, along with the possible solutions.

中文翻译：

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通过延长过渡态的寿命实现低功耗、非相干光触发的双光子吸收

具有多光子吸收（MPA）特性的材料非常适合深部肿瘤治疗、高时空分辨率生物成像、复杂的微纳制造、光学数据存储、上转换激光和光限幅等应用。经典的双光子吸收（TPA）过程依赖于寿命极短的美德态，因此需要飞秒脉冲激光的超高功率密度。为了打破这一应用障碍，关键的解决方案是延长 TPA 中过渡态的寿命。最近，利用单还原物质（如自由基阴离子）和染料分子的三重激发态作为过渡态，实现了低功率非相干激发（LPNC-TPA）的操作。寿命。在这篇综述中，将首先介绍这些 LPNC-TPA 过程的机理，然后介绍延长单还原物质和三重态寿命的方法。然后，考虑到其调节染料分子聚集模式的能力，金属有机框架（MOF）将被强调作为在固态下高效运行 LPNC-TPA 的有效工具。 LPNC-TPA材料的优点和特点将通过其在光氧化还原催化、光聚合、3D打印、体内癌症治疗、生物成像和生物传感方面的新兴应用来揭示。最后，提出了LPNC-TPA的未来方向和挑战，以及可能的解决方案。