Dresden 2017 – wissenschaftliches Programm
CPP 59.5: Vortrag
Donnerstag, 23. März 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 Lemmer1,3, and •Ian Howard1,3 — 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.