Limit of Exciton Diffusion in Highly Ordered 蟺-Conjugated Systems

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• 作者：Pedro Henrique de Oliveira Neto ; Dem茅trio A. da Silva Filho ; Wiliam F. da Cunha ; Paulo H. Acioli ; Geraldo Magela e Silva
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：August 27, 2015
• 年：2015
• 卷：119
• 期：34
• 页码：19654-19659
• 全文大小：348K
• ISSN：1932-7455

文摘

There are many limiting factors in the efficiency of organic photovoltaic devices. One of these factors is their diffusion length or alternatively the diffusivity of excitons, the quasi-particles responsible for the energy conversion. In this work, we investigated the limit of diffusion of excitons in 蟺-conjugated systems. Using a model Hamiltonian that included electronic and strong electron鈥損honon coupling, and including quantum corrected thermal effects through Langevin dynamics, we determined how excitons diffuse within a highly ordered polymer composed of many identical monomers. We established that the exciton follows a typical 1-dimensional random walk diffusive behavior. The diffusivity followed a Marcus behavior with a very low activation energy of 15 meV and a room temperature diffusivity constant of 6.12 脳 10^鈥? cm²/s. We obtained the maximum diffusion constant of 1.1 脳 10^鈥? cm²/s. This is the upper limit of exciton diffusivity in 蟺-conjugated systems as the systems modeled are highly ordered and contained no impurities and the excitons are very delocalized, justifying the low activation barrier and the high diffusion constant.