Extension of Intramolecular Charge-Transfer State Lifetime by Encapsulation in Porous Frameworks,The Journal of Physical Chemistry C

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Extension of Intramolecular Charge-Transfer State Lifetime by Encapsulation in Porous Frameworks
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2017-09-18 00:00:00 , DOI: 10.1021/acs.jpcc.7b06770
Natalya A. Garcia ₁ , Tim Kowalczyk ₁

Affiliation

Control over excited-state lifetimes and relaxation pathways in chromophoric materials is a major challenge in the optimization of photovoltaic energy conversion and photochemical energy storage mechanisms. In light of experimental evidence that the charge-transfer excited-state lifetime of 9-mesityl-10-methylacridinium ion (MesAcr⁺) can be dramatically extended via encapsulation in the mesoporous aluminosilicate AlMCM-41, we employ multiscale simulations to uncover a mechanism for the suppression of charge recombination of MesAcr⁺ in AlMCM-41. The simulations reveal that solvation in acetonitrile and encapsulation in AlMCM-41 have opposing effects on the reorganization energy of MesAcr⁺: solvation substantially raises the reorganization energy while the encapsulation lowers it. Because charge recombination in MesAcr⁺ takes place deep within the Marcus inverted region, the smaller reorganization energy observed in solvent-free AlMCM-41 raises the activation barrier for excited-state charge recombination. Implications for the design of encapsulated chromophores to extend excited-state lifetimes for energy conversion applications are discussed.

中文翻译：

通过多孔框架中的封装来延长分子内电荷转移状态的寿命

发色材料中激发态寿命和弛豫途径的控制是优化光伏能量转换和光化学能量存储机制的主要挑战。鉴于实验证据表明，通过包封在介孔硅铝酸盐AlMCM-41中可以显着延长9-间苯甲基-10甲基rid离子（MesAcr ⁺）的电荷转移激发态寿命，我们采用多尺度模拟来揭示机理抑制AlMCM-41中MesAcr ⁺的电荷重组。模拟显示乙腈中的溶剂化和AlMCM-41中的封装对MesAcr ⁺的重组能有相反的影响：溶剂化实质上提高了重组能，而封装则降低了重组能。由于MesAcr ^+中的电荷重组发生在Marcus反向区域的深处，因此在无溶剂的AlMCM-41中观察到的较小重组能提高了激发态电荷重组的激活势垒。讨论了设计包封的生色团以延长激发态寿命以用于能量转换应用的意义。

更新日期：2017-09-19

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