Near-Infrared Organic Single-Crystal Nanolaser Arrays Activated by Excited-State Intramolecular Proton Transfer

Abstract

<h2>Summary</h2> Near-infrared (NIR) solid-state lasers (SSLs) have advanced telecommunication, spectroscopy, and medical diagnosis. However, the development of organic NIR SSLs still faces severe challenges due to the low stimulated emission of narrow-band-gap molecules and the lack of the effective four-level energy system for population inversion. Here, we fabricated organic single-crystal nanowire arrays based on an excited-state intramolecular proton transfer (ESIPT)-active organic small molecule. The dynamic intramolecular proton transfer within ∼2.5 ps verified the establishment of the four-level energy system. Consequently, room-temperature single-mode 775-nm lasing with a low lasing threshold <i>P</i>_th of 9.9 μJ cm⁻² is achieved from the nanowire arrays with the length of <i>L</i> = 10 μm. Our work gives the unambiguous demonstration of the mechanism of ESIPT lasers and the first realization of organic nanolaser arrays over 760 nm, which will boost the practical application of integrated organic coherent light sources at near-infrared wavelength.