Mechanochromic Organic Micro‐Laser

This work presents the first demonstration of a mechanochromic organic micro-laser, which exhibits remarkable wide range pressure sensing characteristics. The gain material, pinacolato boronate ester functionalized anthanthrene (AnBPin), is designed by incorporating mechanofluorochromic (MFC) properties into organic laser dye. The AnBPin exhibits a reversible transition between green and orange fluorescence upon grinding annealing and recrystallization cycle, and its micro-crystal exhibits typical organic micro-laser behaviors. Applying localized mechanical pressure as low as 0.1 MPa inhibits micro-laser behavior at the given spot. In contrast, under 1 to 2 GPa hydrostatic pressure, the organic laser maintains narrow emission while showing a pressure-dependent shift in emission wavelength. By combining theory and experimentation, we attribute the unusual pressure-correlated emission spectroscopy to the unique interleaved locked crystal structure. Understanding the mechanochromic laser behavior in AnBPin micro-crystals under an unprecedented pressure range significantly expands the family of organic micro-lasers and provides a new route for wide-range photonic pressure detection.