Fabrication of Flexible High‐Temperature Film Thermometers and Heat‐Resistant OLEDs Using Novel Hot Exciton Organic Fluorophores

Abstract

The development of organic thermosensitive fluorophores for use in heatresistant organic light emitting diodes (OLEDs) and large-area and flexible high-temperature sensing remains challenging due to the susceptibility of such materials to thermally facilitated nonradiative decay. A series of "hot exciton" materials ("C1" and "C2") based on pyrrole-substituted triarylphosphine oxides that exhibit high heat resistance have been developed. At a temperature of 260 °C, the films retain 42% (C1) and 29% (C2) of their room temperature fluorescence. This is thanks to thermally facilitated reverse intersystem crossing (RISC) from a high-lying triplet to a singlet state. By combining the novel fluorophores with a yellow emitter with an extremely large Stokes shift, flexible and large-area ratiometric film thermometers are fabricated that demonstrate naked-eye high-temperature sensing. The relative sensitivity, S r , of the film thermometer is higher than 1% K -1 in the high-temperature region (393 to 470 K), with the maximum S r reaching 1.26% K −1 at 430 K. Using these blue emitters, heat-resistant cyan and white OLEDs are also fabricated. With thermally populated singlets and nearly 100% exciton harvesting via fast RISC, the C1-based cyan OLED exhibits a nearly 12-fold enhancement in electroluminescence on heating from room temperature to 530 K, while the corresponding white OLED displays a 5.7-fold electroluminescence enhancement.

Back in bismuth: controlling triplet energy transfer, phosphorescence, and radioluminescence via supramolecular interactions

“…Materials with stable and attainable triplet excited states are important for applications such as photocatalysis, 1–4 electronic displays, 5–9 and sensors. 10–12 A variety of methods have been used to achieve triplet state excitation.…”

Versatile Ratiometric Fluorescent Thermometer Based on Antirigidochromic Fluorophores in a Polymer Matrix with Exceptional Anti-Interference Capability

“…Even when a glass slide was placed between the metal block and the fluorescence detector (or observer), the fluorescence could still be clearly observed through the glass slide, allowing for the recording of temperature changes (Figure S15c). In contrast, conventional infrared (IR) cameras, commonly used for temperature measurements in diverse fields, failed to acquire the temperature of the area blocked by the glass slide (Figure a,b). , Furthermore, the IR image of the metal block captured by the IR camera did not exhibit a clear color transition from bottom to top, indicating a lower spatiotemporal resolution for temperature mapping (Figure d). During the cooling process, the fluorescence of the PTF1/pPFPA film reverted to its initial green-yellow state (refer to Figure S15d), further confirming its excellent reversibility.…”

Heat Resistant Organic Dyes for High Temperature Luminescent Temperature Sensing

“…In our previous studies, many efforts have been focused on the simultaneous prohibition of energy transfer and the development of heat-resistant organic luminophores for preparing sensitive high-temperature ratiometric thermometers. [50][51][52][53] In this work, by hybridizing a blue emitter possessing high heat tolerance with a yellow emitter exhibiting a large stokes shift, energy-transfer-blocked film thermometers have been fabricated for sensitive and high-temperature sensing and find good application in large area thermomapping and multiple encryption. [54][55]…”