др Ненад Вукмировић

03. децембра 2021.

У оквиру семинара Центра за изучавање комплексних система Института за физику у Београду, у четвртак, 09. децембра 2021. године у 14 часова путем Zoom платформе, др Ненад Вукмировић (Лабораторија за примену рачунара у науци, Центар за изучавање комплексних система, Институт за физику у Београду), одржаће предавање:

Charge pair transport pathway in organic solar cells


Solar cells based on organic semiconductors have been widely investigated in the last three decades with a continuous improvement in their performance and lifetime and improved understanding of the processes that take place in the device. The first part of the talk will consist of a brief review of this research field and a review of our previous efforts aimed at understanding the key process in the solar cell – the separation of photo-generated charge pairs (excitons). Our recent results will be presented in the second part of the talk [1, 2]. We model the system using a microscopic effective Hamiltonian that takes into account the most relevant processes that determine the dynamics of excitons. The results for energy and time resolved dynamics of charge pairs from the moment of their photogeneration to the moment of their extraction or recombination will be presented. The results indicated that charge separation proceeds via the cold pathway in which donor excitons convert to relaxed charge-transfer excitons which further transform to the states of separated charges [1]. We further analyze these results from the perspective of non-equilibrium thermodynamics. We determine the difference between equilibrium and non-equilibrium dependence of free energy on charge pair separation distance. Our results indicated that this difference is largest when charge separation efficiency is large which led us to conclude that charge separation in efficient organic solar cells proceeds via a cold but nonequilibrated pathway [2].

[1] V. Janković and N. Vukmirović, J. Phys. Chem. C 124, 4378 (2020).
[2] W. Kaiser, V. Janković, N. Vukmirović, and A. Gagliardi, J. Phys. Chem. Lett. 12, 6389 (2021).

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Meeting ID: 899 4920 6726
Passcode: 819948