Organic molecules which can undergo excited-state intramolecular proton transfer (ESIPT) process have been considered as ideal gain materials for near-infrared organic lasers owing to their effective four-level systems. However, extending lasing wavelength beyond 800 nm with present ESIPT-active gain materials is still in challenge. Herein, we established a molecular design strategy that operates via extending the π-conjugated system of the ESIPT parent core to enhance the cascaded double ESIPT process and thus to achieve the red-shifted six-level system lasing.
View Article and Find Full Text PDFThermally activated delayed fluorescent (TADF) materials have attracted increasing attention because of their ability to harvest triplet excitons via a reverse intersystem crossing process. TADF gain materials that can recycle triplet excitons for stimulated emission are considered for solving the triplet accumulation problem in electrically pumped organic solid-state lasers (OSSLs). In this mini review, recent progress in TADF gain materials is summarized, and design principles are extracted from existing reports.
View Article and Find Full Text PDFNear-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.
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