Organic Crystalline Optical Waveguides That Remain Elastic from −196 to ≈200 °C

Abstract

Organic crystals that are capable to deform (reversibly or irreversibly) similar to polymer materials have been widely reported over the past ten years. However, most of the reported organic crystals can only be elastically bent within a narrow temperature range, and reports on their thermal behavior that would encourage applications of these energy‐transducing elements in extreme conditions are not readily available. This work designs a linear and flat π‐conjugated molecule with double intramolecular hydrogen bonds that prevent thermally induced conformational distortions. The molecule assembles as a rigid building block into centimeter‐sized wide organic crystals that can be elastically bent over a temperature range spanning close to 400 °C, from −196 to ≈200 °C. The emission wavelength of the crystals is also temperature dependent, and can be continually tuned from 547 to 577 nm upon heating from 20 to ≈200 °C. This inspires the design of a lightweight, organic, elastic optical waveguide where the output energy is controlled by the operating temperature. The wide range of crystal flexibility expands the range of conditions for application of organic crystals as optical waveguides.

Organic Crystals with Polymorph-Dependent Mechanical and Thermal Responsive Properties

“…The occurrence of fluorescence quenching due to an increased temperature was a widely observed phenomenon. However, P- 1 exhibited a more pronounced temperature dependence in its fluorescence compared to most crystals reported in previous studies . Upon fitting the fluorescence intensity to the temperature, it was discovered that the two variables exhibited an exponential correlation (Figure d).…”

“…There has been a growing demand for innovative materials that can surmount these limitations and deliver enhanced thermal sensing capabilities. In recent years, the realm of flexible organic crystals has emerged as a captivating field of research, offering distinctive prospects for the advancement of sophisticated materials. − These materials possess the ordered structure characteristic while also exhibiting flexibility, granting them broad adaptability across diverse domains. − Particularly intriguing is their potential application in thermal monitoring, enabling the achievement of meticulous temperature detection in a range of environments. − Flexible organic crystals inherently possess advantages that position them as promising candidates for thermal sensing applications. Their flexibility allows them to conform to irregular surfaces and withstand mechanical deformations, thereby facilitating the seamless integration into an array of flexible electronic devices and systems.…”

Stimuli-responsive flexible organic crystals

“…158 Since 2018, Zhang's team systematically explored the application of adaptive crystals in the field of optical waveguides based on a series of derivatives of single-benzene, Schiff base compounds, β-diketone derivatives, hydrazone compounds, and anthracene derivatives. 79,88–105 In addition, mechanically reconfigurable organic crystals could also be used for amplifying spontaneous emission and in polarization rotators, which broaden their applications in different scenarios. 31,106–115…”

“…21, 4c ), which shows elastically deformable ability over a wide temperature range from −196 °C to 200 °C. 104 The emission wavelength of the crystals is also temperature dependent and can be continually tuned from 547 to 577 nm upon heating from 20 °C to 200 °C. This provides ideas for the design of flexible waveguide tuners.…”

“…158 Since 2018, Zhang's team systematically explored the application of adaptive crystals in the field of optical waveguides based on a series of derivatives of single-benzene, Schiff base compounds, b-diketone derivatives, hydrazone compounds, and anthracene derivatives. 79,[88][89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105] In addition, mechanically reconfigurable organic crystals could also be used for amplifying spontaneous emission and in polarization rotators, which broaden their applications in different scenarios. 31,[106][107][108][109][110][111][112][113][114][115] Huang et al reported the first case of elastic self-doping organic single crystals (1o) that exhibit flexible optical waveguides and amplified spontaneous emission properties (Fig.…”