Small molecule organic solar cells A PhD project by Arkadiusz-Jaroslaw Goszczak.

Supervised by: Horst-Günter Rubahn, Morten Madsen, James Hoyland and Stefan Mátéfi-Tempfli.

September 2012-August 2015

Introduction

Increasing the efficiency of Organic Solar Cells (OSC) by implementation of metal nanostructures has been puzzling many researchers within the past years. It is the aim of this project to develop a method that will result in efficiency enhancement of OSC by structuring the electrodes at the nanoscale, with the use of metal nanoparticles/nanowires via a rapid fabrication method, combined with growth control for optimizing the morphology of the active organic layers.

NanoSYD, Mads Clausen Institutet, Syddansk Universitet, Alsion 2 DK-6400 Sønderborg, Danmark

www.sdu.dk/nanosyd

1) In-house made Knudsen cell. 2) Organic material travels trough the high

vacuum towards substrate. 3) Shutter preventing undesired material

deposition. 4) Sample holder with heating ability. 5) Quartz microbalance for thickness and

deposition rate monitoring.

Deposition of organic material

An OMBD system has been constructed in order to deposit organic material for solar cell architecture.

1) Vivian E. Ferry et al., Optics Express, Vol. 18, Issue S2, pp. A237-A245 (2010)

2) Richard S. Kim et al., Optics Express, Vol. 20, Issue 12, pp. 12649-12657 (2012)

Why plasmonic structures?

Plasmonic structures enhance light trapping (1) and light absorption (2)

Rather easy to fabricate Tunable structures Easy implementation in solar cell structure

Schematic representation of light trapped and reflected within the cell

Conclusion

The projects overall aim is to fabricate Ag plasmonic nanostructures and investigate their

role in organic solar cells. A comparison with the already fabricated bilayer organic solar cells is

going to open new paths towards future research.

First part of the project

Fabrication of metal nanoparticles/wires by electrochemical deposition in porous alumina film is a well-established method for obtaining nanostructures of tailored dimensions on a large scale. As one part of this project, Silver (Ag) nanoparticles, fabricated from the above method, will be developed for use in food toxicology investigations, where the effect from different nanoparticles or nanowires is still not known. Hence a first part of this project will be to fabricate such nanowires to investigate the effect from different size Ag structures in the food toxicology area.

Second part of the project Additionally the knowledge obtained from the fabrication of such Ag nanostructures shall be used for the development of plasmonic nanostructures for novel OSC’s. This shall be done in a two-step process. First by developing planar OSC devices using small molecules deposited via Organic Molecular Beam Deposition (OMBD) and characterizing them by standard I-V measurement. Secondly by fabricating nanostructured electrodes from the above method that shall be characterized both morphologically and optically. Growth control of the active organic layers is also a key point for obtaining efficiency enhancement in the developed nanostructured organic solar cells.

Aluminum on Si Anodization and pore creation

Electrodeposition of Ag and nanowire fabrication

Al Anodization and growth of Ag nanowires

Implementation of nanowires in solar cell

structure.

Collection of Ag nanowires in solution