Cascaded Excited‐State Intramolecular Proton Transfer Towards Near‐Infrared Organic Lasers Beyond 850 nm

Abstract

Near-infrared (NIR) organic solid-state lasers play an essential role in applications ranging from laser communication to infrared night vision, but progress in this area is restricted by the lack of effective excited-state gain processes. Herein, we originally proposed and demonstrated the cascaded occurrence of excited-state intramolecular proton transfer for constructing the completely new energy-level systems.Cascading by the first ultrafast proton transfer of < 430 fs and the subsequent irreversible second proton transfer of ca. 1.6 ps,the stepwise proton transfer process favors the true six-level photophysical cycle,w hichs upports efficient population inversion and thus NIR single-mode lasing at 854 nm. This work realizes longest wavelength beyond 850 nm of organic single-crystal lasing to date and originally exploits the cascaded excited-state molecular proton transfer energy-level systems for organic solid-state lasers.

Cascaded Excited‐State Intramolecular Proton Transfer Towards Near‐Infrared Organic Lasers Beyond 850 nm

“…a) X-ray structure of DDMP. [34] b) Molecular packing arrangement in DDMP single crystal. c) Growth morphology of the DDMP molecules simulated by the MaterialsS tudio software.…”

Thermally Activated Delayed Fluorescent Gain Materials: Harvesting Triplet Excitons for Lasing

“…[ 21 ] For some organic molecules, phototautomerization reactions, such as excited‐state intramolecular proton transfer (ESIPT), can occur during excitation, in which more effective four‐level energy systems can be formed by the ground and first excited states of normal forms and tautomer forms. [ 22–25 ] This type of more effective four‐level energy system can lead to easier population inversion and further result in a lower laser threshold. To date, various organic materials, such as dyes, polymers, metal complexes, and semiconductive molecules, have been developed and investigated as gain materials in OSSLs.…”

Recent Progress of Novel Organic Near‐Infrared‐Emitting Materials

“…[ 6 ] Representative cases include conjugated polymers, [ 7 ] organic rare‐earth/noble metal complexes, [ 8 ] and small‐molecule dyes. [ 9 ] Considering an advanced work reported by Prof. P.‐T. Chou and co‐workers, a new class of phosphorescent platinum(ii) complexes demonstrated charming NIR emission at 866‐960 nm with a PLQY of 5–12% in solid films [2b] .…”