Dresden 2017 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 59: Focus: Static and Dynamic Disorder Phenomena on the Transport in Organic Semiconductors II

CPP 59.5: Talk

Thursday, March 23, 2017, 16:45–17:00, ZEU 222

Identifying Charge Transfer States in Polymer:Fullerene Heterojunctions by Their Emission Polarization Anisotropy — Andreas Arndt¹, Marina Gerhard², Martin Koch², Uli Lemmer^1,3, and •Ian Howard^1,3 — ¹Karlsruhe Institute of Technology (Light Technology Institute), Karlsruhe, Germany — ²Philipps-Universität Marburg, Marburg, Germany — ³Karlsruhe Institute of Technology (Institute of Microstructure Technology), Karlsruhe, Germany

It is well understood that the separation of charge carriers from donor:acceptor heterojunctions in organic photovoltaic blends is significantly affected by the distribution of charge-transfer states present at the disordered material interface. Recombination of charge carriers held in charge-transfer states can be emissive, meaning the emission spectrum of the charge-transfer states reveals information about interfacial disorder. However, the assignment of charge-transfer state emssion can be controversial, especially when the offset to low-energy excitonic emission is small. In this contribution, we present the time-resolved photoluminescence (PL) polarization anisotropy of several organic photovoltaic blends. Our results demonstrate that the charge-transfer state emission can be identified with a high degree of certainty by its unique negative polarization anisotropy. The unique negative anisotropy arises due to the significant rotation of the transition dipole moment upon charge-transfer at the donor-acceptor interface.