Regensburg 2013 – wissenschaftliches Programm
BP 4.4: Hauptvortrag
Montag, 11. März 2013, 11:00–11:30, H1
Efficient Exciton Generation and Collection in Organic Solar Cells — •Mark Thompson1, Cong Trinh1, Steve Forrest2, and Jeramy Zimmerman2 — 1University of Southern California, Los Angles, CA, USA — 2University of Michigan, Ann Arbor, MI, USA
The exciton is a critical part of each of the processes leading to photocurrents in Organic PhotoVoltaics (OPVs), and being able to control the location, lifetime and energy of the exciton is essential to achieving high efficiency. We have investigated methods for tuning exciton energies and controlling their migration paths within a thin film. I will discuss our most recent work with both organic dyes, such as squaraines and dipyrrins as well as metallo-porphyrin materials for OPVs. This involves a careful materials design study that leads to both low energy absorption (into the nearIR) and the efficient use of multiple absorbers to efficiently harvest photons through the entire visible spectrum.
A key limiter of OPV performance is the open circuit voltage, Voc. A number of parameters control the Voc, including the energetics of the donor and acceptor, the energy of the charge transfer exciton formed at the D/A interface and the structure of the materials at the D/A interface. We have investigated methods to tailor the interfacial structure at the D/A interface, leading to improved Voc. We have investigated thermal and solvent annealing, as well as a process we call chemical annealing, where the thin film is exposed to an external agent, which is incorporated into the film stoichiometrically. I will discuss each of these methods and how they affect the device performance.