Growth of Few-Layer Molecular Crystals of PTCDI on Hexagonal Boron Nitride by Microspacing Air-Gap Sublimation

• Published in: ACS applied optical materials Vol. 3; no. 2; pp. 455 - 462
• Main Authors: le Coutre, Nils, Abdurakhmonov, Tolibjon, Weinbrenner, Paul, Watanabe, Kenji, Taniguchi, Takashi, Korn, Tobias, Fennel, Franziska, Kühn, Oliver, Reinhard, Friedemann
• Format: Journal Article
• Language: English
• Published: American Chemical Society 28.02.2025
• Subjects: layered growth; DFT; fluorescence; hBN; physical vapor deposition; PTCDI; polarization
• ISSN: 2771-9855; 2771-9855
• DOI: 10.1021/acsaom.4c00522

Extended two-dimensional (2D) crystals of dye molecules adsorbed on 2D material substrates such as boron nitride have recently become a subject of intense study, with potential applications ranging from quantum technology to optoelectronics. The most established technique for the production of these films is physical vapor transport in a vacuum. We demonstrate that few-layer crystalline films of the organic dye molecule perylenetetracarboxylic diimide (PTCDI) on boron nitride can be produced by microspacing in-air sublimation, a radically simplified technique that does not require complicated vacuum systems. The resulting layers display clearly resolved atomic step terraces in atomic force microscopy and a clear polarization anisotropy in their fluorescence, confirming molecular alignment and long-range order. Using density functional theory and classical molecular dynamics simulations, the canted motif is identified as the most likely building block for the morphology of a PTDCI monolayer on the hBN substrate.