Regensburg 2022 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 25: Poster 1

HL 25.52: Poster

Wednesday, September 7, 2022, 18:00–20:00, P2

The Impact of Mechanical Stress on Structural, Morphological and Electrical Properties of Transferable Organic Semiconductor Nanosheets — •Veronika Reisner, Sirri Batuhan Kalkan, and Bert Nickel — Faculty of Physics and CeNS, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, 80539 Munich, Germany

Recently, we presented a technique to transfer organic small-molecule nanosheets using a sacrificial water-soluble polymer layer. This approach enables the transfer of highly ordered organic films on substrates, which are unfavorable for direct growth by physical vapor deposition. However, the transferable nanosheets experience a considerable amount of mechanical stress during the release and transfer process. Here, we investigate the structural and morphological changes induced in the transferable nanosheets to optimize the transfer technique. For this purpose, we use pentacene films as stress sensors. Pentacene films show a distinct response to the mechanical stress by an irreversible phase change from the thin-film phase to the Campbell bulk phase. To reveal these structural and morphological changes, we employ X-ray diffraction analysis and atomic force microscopy technique. We find that thinner pentacene nanosheets show a lower Campbell bulk phase contribution after the transfer process. Finally, we use an optimized transfer technique to fabricate transistors based on the transferable organic small-molecule DNTT. DNTT nanosheets are more brittle compared to pentacene nanosheets but exhibit superior device performance.