Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 102: Organic electronics and photovoltaics: Devices (CPP with HL/TT)

HL 102.7: Invited Talk

Friday, March 20, 2015, 11:30–12:00, C 130

Excitonic phenomena in molecular semiconductors — •Jens Pflaum — Experimental Physics VI, Julius Maximilian University of Würzburg, 97074 Würzburg — ZAE Bayern, 97074 Würzburg

Excitons constitute the primary electron-hole excitation in organic solid states and offer a broad range of photo-physical phenomena. In this talk we will address two key aspects of excitonic states in molecular semiconductors: i) their sensitivity to structural ordering on various length scales and ii) their implementation as recombination sites yielding access to microscopic current characteristics.

In case of i), we will discuss the impact of molecular packing on the exciton motion [1] and how long-range exciton diffusion enables access to boundary-induced trap states that might lead to suppression of otherwise prominent singlet exciton decay channels [2]. Regarding ii), the non-invasive optical read-out of molecular recombination dynamics will be demonstrated to provide information on the local current density [3]. As a consequence, by utilizing the triplet emission of suited molecules this approach paves the way towards electrically driven single photon sources operating at room temperature [4]. Financial support within the DFG research programme SPP1355 and FOR1809 is acknowledged.

[1] A. K. Topczak, et al., Phys. Rev. B 89, 201203(R) (2014).

[2] B. Gieseking, et al., Phys. Rev. B 90, 205305 (2014).

[3] B. Stender, et al., Adv. Mater. 25, 2943 (2013).

[4] M. Nothaft, et al., Nature Comm. 3, 628 (2012).