Fluorescence-based thermal sensing with elastic organic crystals

Abstract

Operation of temperature sensors over extended temperature ranges, and particularly in extreme conditions, poses challenges with both the mechanical integrity of the sensing material and the operational range of the sensor. With an emissive bendable organic crystalline material, here we propose that organic crystals can be used as mechanically robust and compliant fluorescence-based thermal sensors with wide range of temperature coverage and complete retention of mechanical elasticity. The exemplary material described remains elastically bendable and shows highly linear correlation with the emission wavelength and intensity between 77 K to 277 K, while it also transduces its own fluorescence in active waveguiding mode. This universal new approach expands the materials available for optical thermal sensing to a vast number of organic crystals as a new class of engineering materials and opens opportunities for the design of lightweight, organic fluorescence-based thermal sensors that can operate under extreme temperature conditions such as are the ones that will be encountered in future space exploration missions.

An Elastic Organic Crystal Enables Macroscopic Photoinduced Crystal Elongation

“…Mechanically adaptive molecular crystals, which deform but do not break when they are subjected to stress, are promising materials for applications in compliant organic electronics, artificial muscles, and actuating devices. − While new elastic and plastic molecular crystals continue to be reported, − the criteria and scope in molecular configuration, crystal packing mode, and nonbonded interactions toward crystal elasticity or plasticity remain to be established. − In addition, the phenomenon of photochemical-reaction-triggered crystal deformation is well-documented, − but examples of photoinduced crystal elongation are very rare and are limited to microcrystals, − because of the ease of crystal disintegration (e.g., fragmentation and splitting) during the expansion process. The increased tendency for larger or thicker crystals to break − ,− indicates that strain-induced molecular reconfiguration in the interior bulk of crystals is much less efficient than that near the crystal surface.…”

Two-Dimensional Optical Waveguides at Telecom Wavelengths Based on Organic Single-Crystal Microsheets of a Charge Transfer Complex

“…An organic charge transfer (CT) cocrystal strategy is considered as a feasible way to prepare low-dimensional materials due to its unique advantages . Organic crystals with regular structure and adjustable optical properties have been widely studied as good optical waveguide media. − Compared with individual components, organic CT complexes have abundant novel physical and chemical properties . The properties and structures of CT complexes can be precisely controlled by selecting appropriate donor–acceptor (D–A) molecules for self-assembly .…”

Organic Single Crystal/Polymer Hybrid Actuator with Waveguide, Low Temperature, and Humidity Actuation Properties

“…Upon mechanical stimulation, both (002) and (100) faces could undergo elastic bending. Combining the literature 32,56,57 and this work, we speculated on the mechanism of crystal elastic bending as follows: weak intermolecular interactions could effectively absorb and dissipate the mechanical force, thereby rendering the crystal more susceptible to stress. Upon bending, the intermolecular distances between the outer arc molecules in the (002) and (100) faces increased, and the intermolecular distances between the inner arc molecules decreased to accommodate the above changes.…”