A bodipy–C₇₀ dyad was synthesized and applied in triplet–triplet annihilation (TTA) upconversion of perylene as a novel metal-free organic photosensitizer. The photophysical processes were investigated by the methods of steady-state UV-Vis absorption and fluorescence spectroscopy, nanosecond time-resolved transient absorption spectroscopy, cyclic voltammetry, and density functional theory calculations. The bodipy–C₇₀ dyad showed an increased molar extinction coefficient up to 82 300 mol⁻¹ cm⁻¹ at 518 nm compared with the C₇₀ monomer. With photo-excitation of the bodipy moiety at 532 nm, the intramolecular singlet–singlet energy transfer between bodipy and C₇₀ units was efficient with a quantum yield of nearly 100%, and the lowest triplet state of the dyad was subsequently populated via ISC of the C₇₀ moiety, with a lifetime of ca. 80 μs in toluene. Electrochemical investigation suggested that the intramolecular electron transfer of the excited dyad was thermodynamically prohibited in toluene due to the positive ΔG_CS for charge-separation. With the presence of perylene in solution as the triplet energy acceptor and emitter, the TTA upconverted fluorescence was observed with a maximum quantum yield of 10.3%. The overall upconversion capability of 4417 M⁻¹ cm⁻¹ exceeded that of C₇₀ approximately two-fold. Moreover, the bodipy–C₇₀ dyad also exhibited an enhanced optical stability under intense irradiation. All data indicated that the dyad was another ideal photosensitizer for TTA upconversion of perylene in the fullerene derivative family.

中文翻译：

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Bodipy-C ₇₀二联体在per的三重态-三重态up灭上转换中作为无金属光敏剂的应用†

合成了Bodipy-C ₇₀双染料，并将其用于applied的三重态-三重态let灭（TTA）上转换，作为一种新型的不含金属的有机光敏剂。通过稳态UV-Vis吸收和荧光光谱法，纳秒级时间分辨瞬态吸收光谱法，循环伏安法和密度泛函理论计算方法研究了光物理过程。与C ₇₀单体相比，bodipy-C ₇₀二聚体在518 nm处的消光系数增加至82 300 mol ^-1 cm ^-1。在532 nm处对bodipy部分进行光激发后，bodipy与C ₇₀之间的分子内单重态-单重态能量转移单位是有效的，具有接近100％的量子产率，随后通过C ₇₀部分的ISC填充了最低的三联体状态，寿命约为。甲苯中80μs。电化学研究表明，由于用于电荷分离的ΔG _CS为正值，因此在甲苯中热力学上阻止了受激二重物的分子内电子转移。在溶液中存在per作为三重态能量受体和发射体的情况下，观察到TTA上转换的荧光，最大量子产率为10.3％。4417 M ^-1 cm ^-1的整体上转换能力超过了C ₇₀大约两倍。此外，bodipy-C ₇₀ dyad在强辐射下也表现出增强的光学稳定性。所有数据表明，对于富勒烯衍生物家族中per的TTA上转换，该二元组是另一种理想的光敏剂。