Dresden 2011 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 8: Poster: Organic Semiconductors
CPP 8.32: Poster
Monday, March 14, 2011, 17:30–19:30, P2
Tetrapropyl-tetraphenyl-diindenoperylene derivative as new donor for organic solar cells — •Jan Meiss, Martin Hermenau, Wolfgang Tress, Markus Hummert, Christoph Schuenemann, Karl Leo, and Moritz Riede — Institut für Angewandte Photophysik, Technische Universität Dresden, 01062 Dresden, Germany
We show a diindenoperylene derivative (P4-Ph4-DIP) as green donor for heterojunction organic solar cells (OSC). OSC are characterized by current voltage, EQE, and ageing measurements. Devices with C60 as acceptor display very high fill factors FF of over 76% and open circuit voltages VOC of 0.99 V. A clear influence of donor thickness td on short circuit current density JSC and FF is visible: with td = 9 nm, JSC is enhanced from 1.8 mA/cm2 (reference device with only C60 as absorber) to 2.6 mA/cm2, reaching FF = 75.7% with VOC = 0.98 V (η = 1.9±0.1%). At higher td of up to 63 nm, photocurrent and FF decrease, ultimately dropping below the characteristics of the reference device. We find an EQE of 23% at the position of the donor main absorption peaks (493 nm, 525 nm, and 568 nm), reaching highest efficiencies at td of 9 - 12 nm and then decreasing with higher td. We attribute this to a limited exciton diffusion length LD in the donor: at high td, the material absorbs photons, but excitons do not reach the heterointerface for dissociation and thus cannot contribute to the photocurrent. By combining measured J(V) data with calculations, we show that LD = (9±1) nm fits well to the experimental findings. Ageing experiments show that the resulting devices are highly stable when exposed to accelerated ageing.