Side-Chain Engineering of Organic Crystals for Lasing Media with Tunable Flexibility

Abundant high-performance organic crystals have been reported in the past decades; however, applica-tions of crystalline materials are seriously restricted by their notorious brittleness. Recently, some organic crystals have been designed to be deformable in response to stress, light, heat, or humidity; neverthe-less, the development of flexible organic crystals currently relies on a molecular framework design. So far there is no effective strategy for constructing organic crystals with tunable flexibility based on the same luminescent skeleton. Herein, we propose a side-chain engineering strategy aimed at facilely modulating the mechanical compliance of organic crystals. Subtly changing the side chains of a sin-gle-benzene pi-skeleton greatly alters the mechanical behaviors while maintaining the unique optical func-tions of the produced crystals. Optical waveguides and amplified spontaneous emissions were measured to evaluate the application potentials of the flexible crystals as soft optical transducing media. We antici-pate that the proposed strategy will be expanded to regulate the mechanical compliance of other organic crystals with unique emission properties. In addition, the applications attempted preliminarily here high-light the superiority of crystal flexibility in flexible optoelectronics for some special application scenari-os that require complex and shape changeable opti-cal circuits.

Automated summary

Abundant high-performance organic crystals have been reported, but their brittleness restricts their applications. Some organic crystals have been designed to be deformable, but their development relies on molecular framework design. In this study, a side-chain engineering strategy is proposed to easily modulate the mechanical compliance of organic crystals. Changing the side chains subtly alters the mechanical behaviors while maintaining the unique optical functions. The potential applications of the flexible crystals as soft optical transducing media are evaluated through optical waveguides and amplified spontaneous emissions.