Vapor Phase Assembly of Molecular Emitter Crystals for Photonic Integrated Circuits

TL;DR

This paper introduces a vapor-phase growth technique for creating ultra-thin, stable, and tunable organic molecular crystals suitable for integration into photonic circuits, enabling on-chip single-photon sources.

Contribution

The study presents a novel vapor-phase synthesis method for embedding molecular emitters into thin crystals compatible with nanophotonics, maintaining spectral stability and tunable dopant density.

Findings

Crystals are ~200 nm thick with sub-nm roughness.

Molecular transitions are narrow and spectrally stable.

Dopant density is tunable up to several hundred molecules per μm².

Abstract

Organic molecules embedded in an organic matrix exhibit lifetime-limited optical coherence and bright emission at cryogenic temperatures below 3 K. Here we present a simple vapor-phase growth method for synthesizing optically thin DBT-doped anthracene crystals that are compatible with integrated nanophotonics. The crystals are ~200 nm thick with sub-nm surface roughness and a tunable lateral dimension of up to 200 $\mu$m. The molecular transitions remain narrow and spectrally stable, with inhomogeneous broadening below 100 GHz, comparable to DBT in bulk anthracene. The dopant density is tunable up to several hundred molecules per $\mu$m$^2$, ensuring emitters within the near-field of nanophotonic structures. We demonstrate that the crystals can be micropositioned onto integrated photonic devices with the molecular dipole aligned to the optical mode. This approach opens a path toward on-chip single-photon sources and collective many-emitter effects.