Highly Emissive Flexible Organic Crystals with Broad Piezochromism and Optical Waveguides Article Swipe
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· 2025
· Open Access
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· DOI: https://doi.org/10.1002/chem.202500888
· OA: W4409017650
The integration of mechanical flexibility with stimuli‐responsive optical properties in organic single crystals (OSCs) remains a formidable challenge due to the intrinsic rigidity of π‐conjugated systems. Herein, we report a rationally designed OSC, FBCF , that synergistically combines elastic deformability, broad piezochromism, and optical waveguides via a planar benzothiadiazole ( BTA ) core and fluoroarene termini. The molecular architecture enforces face‐to‐face slip‐stacking via multiple noncovalent interactions (N•••H, π‐π, and C‐F•••π), yielding centimeter‐scale crystals with exceptional elastic bending and full recovery. These crystals exhibit high photoluminescence (PL) efficiency (PLQY = 75.8%) and serve as optical waveguides, maintaining performance even when bent (optical loss coefficients (OLCs): 0.286–0.529 dB mm −1 ). Crucially, FBCF exhibits broad pressure‐responsive spectral shifts (Δ λ = 171 nm), achieving a piezochromic sensitivity of 16.7 nm GPa −1 , exceeding that of most organic systems. Single‐crystal X‐ray diffraction analyses reveal hierarchical packing: rigid lamellar layers (stabilized by strong π‐π/dipole interactions, ‐118.56 to ‑58.45 kcal/mol) interconnected via weaker interlayer C‐F•••π bonds (−18.8 kcal/mol). This architecture enables elastic deformation through interlayer slippage while preserving intralayer order.
