Berlin 2024 – scientific programme

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DS: Fachverband Dünne Schichten

DS 6: Thin Film Properties I

DS 6.1: Invited Talk

Tuesday, March 19, 2024, 09:30–10:00, A 060

Concerted electron-nuclear motion in polaron formation and exciton transfer — •Wolf Gero Schmidt — Universität Paderborn

Ab initio molecular dynamics calculations on (excited-state) potential energy surfaces obtained from constrained density-functional theory [1] provide deep insight into the concerted electron-nuclear motion of excited systems and allow for the quantitative modelling of the excitation dynamics [2]. This is demonstrated in my talk using two intriguing examples: (i) The formation of bound polarons in lithium niobate occurs on the femtosecond timescale [3] and modifies significantly the linear and nonlinear optical response [4]. (ii) The transfer of triplet excitons resulting from singlet fission in organic overlayers into Si solar cells is shown to be greatly accelerated by dangling-bond interface defects: The vibrations of Si surface atoms hosting the dangling bonds are associated with defect state energy changes that effectively shuttle the excitons across the interface [5].
[1] O Pankratov, M Scheffler, Phys. Rev. Lett. 75, 701 (1995).
[2] T Frigge et al., Nature 544, 207 (2017); CW Nicholson et al., Science 362, 821 (2018).
[3] M Krenz, U Gerstmann, WG Schmidt, Applied Physics A 128, 480 (2022).
[4] AL Kozub, A Schindlmayr, U Gerstmann, WG Schmidt, Phys. Rev. B 104, 174110 (2021).
[5] M Krenz, Verhandl. DPG (VI) 58, 572 (3/2023).

Keywords: DFT; exciton; interface; solar cell; polaron