Dresden 2014 – scientific programme
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O: Fachverband Oberflächenphysik
O 101: Molecular Films: Electronics, Photovoltaics and Structure
O 101.3: Talk
Friday, April 4, 2014, 11:00–11:15, WIL A317
Pulsed laser deposited ZnO nanostructures with a sol-gel ZnO coating for hybrid solar cells — •Sven Käbisch1,2, Thomas J. K. Brenner3, Norbert H. Nickel1, and Norbert Koch1,2 — 1Helmholtz-Zentrum Berlin GmbH — 2Humboldt-Universität zu Berlin, Institut für Physik — 3Universität Potsdam, Hybrid Photovoltaics & Optoelectronics Group
Hybrid solar cells aim to combine high cross sections for light absorption common for organic semiconductors with high mobility of charge carriers in inorganic semiconductors. Besides the generation and collection of charge carriers in a hybrid solar cell, the charge separation process at the inorganic/organic interface determines the power conversion efficiency (PCE) of the device. Zinc oxide (ZnO) nanostructures and planar layers were deposited by a pulsed laser deposition process on O-terminated Al-doped ZnO planar layers. Subsequently, poly[(bis-(2-ethylhexyl)-cyclopentadithiophene)-alt-benzothiadiazole] (PCPDTBT) was spin-coated on the ZnO nanostructures. The fabrication of the hybrid solar cell was finished by thermal evaporation of molybdenum trioxide and gold as the top electrode. Prior to the formation of the hybrid ZnO/PCPDTBT junction, some of the planar and nanostructured ZnO electrodes were subjected to a surface modification by drop-casting of sol-gel ZnO. Owing to the presence of the structurally imperfect sol-gel layer, the performance of the solar cells could be increased by a factor of 7 for planar and 15 for nanostructured hybrid junctions. This increase of the PCE is explained in terms of an improved charge separation at the ZnO/PCPDTBT interface.