Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 23: Organische Halbleiter

HL 23.5: Talk

Tuesday, March 9, 2004, 17:45–18:00, H13

Polymer-Fullerene Solar Cells with 3.1% Power Conversion Efficiency — •Ingo Riedel, Jürgen Parisi, and Vladimir Dyakonov — Energy- and Semiconductor Research Laboratory, Institute of Physics, University of Oldenburg, D-26111 Oldenburg, Germany

Polymer-fullerene bulk heterojunction solar cells have run through a rapid development over the past 8 years. Power conversion efficiencies in the range 2.5 % - 3 % have been demonstrated. For commonly used absorber materials the insufficient transport properties of the semiconductors require low absorber thickness of 100 nm or below and therefore limit the absorption. A higher active layer thickness, however, is required to increase the amount of absorbed photons and consequently to increase the short-circuit photocurrent of the solar cell.

In this work we demonstrate that by using material components with relatively high mobility-lifetime product it is possible to overcome the transport limitation of the photocurrent. For solar cells based on regioregular poly[3-hexylthiophene 2,5 diyl]:phenyl-C₆₁ butyric acid methyl ester (P3HT:PCBM) composites, the active layer thickness was increased from 50 nm to 350 nm with respective photocurrent densities ranging from 5.7 mA/cm² to 15.4 mA/cm². For the device with 350 nm absorber thickness a power conversion efficiency of 3.1 % at 100 mW/cm² white light illumination was obtained.