Four novel nanographene/porphyrin hybrids were prepared, characterized, and probed in solar energy conversion schemes. Exfoliation of graphite by means of immobilizing four different porphyrins onto the basal plane of graphene is accompanied by distinct electronic interactions in both the ground and the excited states. In the ground state, a strong loss in oscillator strength goes hand-in-hand with a notable broadening of the porphyrin transitions and, as such, attests to the shift of electron density from the electron donating porphyrins to nanographene. In the excited state, a nearly quantitative quenching of the porphyrin fluorescence is indicative of full charge transfer. The latter is corroborated by femtosecond transient absorption measurements, which reveal the generation of the one-electron oxidized radical cation of the porphyrins with absorption maxima at 490 and 625 nm in the visible region and conduction band electrons in nanographene with features at 890 and 1025 nm in the near infrared region. We have demonstrated the applicability of the new nanographene/porphyrin hybrids in, for example, solar cells. In this regard, the presence of flakes is crucial in terms of influencing the injection processes, preventing aggregation, and reducing recombination losses, which are commonly encountered in porphyrin-based DSSCs.
四种新型纳米
石墨烯/
卟啉杂化物被制备、表征,并用于太阳能转化研究。通过将四种不同的
卟啉固定在
石墨烯的基面上,石墨的剥离伴随着在基态和激发态下显著的电子相互作用。在基态中,振荡强度的强烈损失与
卟啉跃迁的显著展宽相伴随,证明了电子密度从电子供体
卟啉转移到纳米
石墨烯。在激发态中,
卟啉荧光几乎完全熄灭,表明发生了完全的电荷转移。后者得到了飞秒瞬态吸收测量的证实,显示出
卟啉的单电子氧化自由基阳离子的生成,其可见区域的吸收峰值在490和625 nm,而纳米
石墨烯中导电带电子的特征则在近红外区域表现为890和1025 nm。我们已证明新型纳米
石墨烯/
卟啉杂化物在例如太阳能电池中的适用性。在这方面,片状结构的存在对影响注入过程、防止聚集和减少
重组损失至关重要,这些问题在基于
卟啉的
染料敏化太阳能电池中常见。