Large Sheet-Like Elastic Crystals for Flexible Organic Light-Emitting Diode

Large sheet-like elastic crystals have vast potential applications in 2D flexible optoelectronic applications, such as information display and imaging, but this potential has been limited as the sheet-like crystal habit is not commonly observed in molecular crystals. Here, we report the crystal structure, mechanical elastic properties, mechanism of deformation, and 2D optoelectronic applications of 2,7-bis(4-methoxyphenyl)-9H-fluoro-9-one (BMeOPhFO). Elastically flexible crystals of 2D BMeOPhFO-R were obtained on a centimeter scale in both length and width. The elastic bending performance and mechanism were studied thoroughly in BMeOPhFO-R and its acicular polymorph BMeOPhFO-O, determined by micro-focused X-ray diffraction. Finally, a preliminary flexible organic light-emitting diode based on an elastic 2D single crystal of BMeOPhFO-R (bending curvature <5 mm) was preliminarily prepared with low driving voltage and electroluminescence. This study will not only promote the future development of flexible molecular crystals with 2D habits, in addition to providing insights for applications in 2D flexible optoelectronics application.