Conformation‐Confined Organic Butterfly‐Molecule with High Photoluminescence Efficiency, Deep‐Blue Amplified Spontaneous Emission, and Unique Piezochromic Luminescence.

Organic fluorophores with tunable π‐conjugated paths have attracted considerable attention owing to their diverse properties and promising applications. Herein, we present a tailored butterfly‐like molecule, 2,2’‐(2,5‐bis (2,2‐diphenylvinyl)‐1,4‐phenylene)dinaphthalene (BDVPN), which exhibits diverse photophysical features in its two polymorphs. The BP phase crystal, with its “aligned wings” conformation, possesses emissive characteristics that are nearly identical to those in dilute solutions. In contrast, the BN phase crystal, which adopts an “orthogonal wings” conformation, exhibits an unusual hypsochromic‐shifted emission compared to its dilute solution counterparts. This intriguing hypsochromic‐shifted emission originates from the reduction in the effective conjugated length of the molecular skeleton. Notably, BN phase crystals also exhibit exceptional optical performance, featuring high‐efficiency emission (76.6 %), low‐loss optical waveguides (0.571 dB mm−1), deep‐blue amplified spontaneous emission (ASE) with narrow full width at half maximum (FWHM: 6.4 nm), and a unique 200 nm bathochromic shift of piezochromic luminescence. [ABSTRACT FROM AUTHOR]