Tailoring the Optical Response of Pentacene Thin Films via Templated Growth on Hexagonal Boron Nitride

Samuel H. Amsterdam, Trevor Lamountain, Teodor K. Stanev, Vinod K. Sangwan, Rafael López-Arteaga, Suyog Padgaonkar, Kenji Watanabe, Takashi Taniguchi, Emily A. Weiss, Tobin J. Marks, Mark C. Hersam, Nathaniel P. Stern

Research output: Contribution to journalArticlepeer-review

Abstract

The optoelectronic properties of organic thin films are strongly dependent on their molecular orientation and packing, which in turn is sensitive to the underlying substrate. Hexagonal boron nitride (hBN) and other van der Waals (vdW) materials are known to template different organic thin film growth modalities from conventional inorganic substrates such as SiO2. Here, the morphology and temperature-dependent optical properties of pentacene films grown on hBN are reported. Pentacene deposited on hBN forms large-grain films with a molecular π-face-on orientation unlike the dendritic edge-on thin-film phase on SiO2. Pentacene/hBN films exhibit a 40 meV lower free exciton emission than pentacene/SiO2 and an unconventional emission energy temperature dependence. Time-resolved photoluminescence (PL) decay measurements show a long-lived signal in the π-face-on phase related to delayed emission from triplet-triplet fusion. This work demonstrates that growth on vdW materials provides a pathway for controlling optoelectronic functionality in molecular thin films.

Original languageEnglish (US)
Pages (from-to)26-31
Number of pages6
JournalJournal of Physical Chemistry Letters
Volume12
Issue number1
DOIs
StatePublished - Jan 14 2021

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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