The conversion of low energy photons into higher energy photons via triplet-triplet annihilation upconversion (TTA-UC) has important implications for wavelength-shifting technology and is a target for increasing the efficiency of solar energy harvesting. Given that the efficiencies of solid-state TTA-UC are drastically lower than that of solution-phase TTA-UC, strategies are needed to augment the process. Herein, hydrogen-bonded organic frameworks (HOFs) comprised of zinc tetrakis(4-carboxyphenyl)porphyrin (Zn-TCPP) acting as the sensitizer and dipyridyl thiazolothiazole (TzBIPY) acting as the annihilator were synthesized and evaluated for TTA-UC. Modifying the coordination angle of the TzBIPY to the porphyrin, two structures were obtained and characterized via single crystal x-ray diffraction. Using both femtosecond laser excitation of the HOFs as colloidal dispersions in solvent and continuous wave laser excitation on single crystal samples, evidence of superlinear power-dependent emission at 460 nm from TzBIPY upon resonant excitation of Zn-TCPP suggests the occurrence of TTA-UC. This investigation illustrates the potential of HOFs for light harvesting applications and could lead to further development in photocatalysis where the HOF is used as the photosensitizer for encapsulated guests.

中文翻译：

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在氢键有机框架中通过固态三重态-三重态湮灭将绿光上转换为蓝光


通过三重态-三重态湮灭上转换 （TTA-UC） 将低能光子转换为高能光子对波长转移技术具有重要意义，并且是提高太阳能收集效率的目标。鉴于固态 TTA-UC 的效率大大低于溶液相 TTA-UC，因此需要策略来增强该过程。在此，合成了由锌四（4-羧基苯基）卟啉 （Zn-TCPP） 作为敏化剂和二嘧啶基噻唑并作为歼灭剂的氢键有机框架 （HOF），并评价了 TTA-UC。修改 TzBIPY 与卟啉的配位角，获得两种结构，并通过单晶 X 射线衍射表征。使用飞秒激光激发 HOFs 作为溶剂中的胶体分散体和单晶样品上的连续波激光激发，Zn-TCPP 共振激发后 TzBIPY 在 460 nm 处的超线性功率依赖性发射证据表明 TTA-UC 的发生。这项研究说明了 HOF 在光收集应用中的潜力，并可能导致光催化的进一步发展，其中 HOF 用作封装客体的光敏剂。