The aggregation-caused quenching (ACQ) phenomenon of organic luminescent molecules in the solid state critically limits the development of organic light-emitting devices. The crystal-induced luminescence or/and stability enhancement (CLoSE) effect, characterized by enhanced luminescence efficiency upon the transition from the amorphous to the crystalline state, offers an effective solution. Herein, we investigated the influence of solvent-molecule hydrogen bonding on molecular self-assembly and the CLoSE effect. The 3-(9-phenyl-9H-fluoren-9-yl)-9H-carbazole (PFCz) molecule, which forms strong N–H···O hydrogen bonds with tetrahydrofuran (THF), yielded two-dimensional (2D) sheet-like crystals whose microcrystalline films exhibited a photoluminescence quantum yield (PLQY) of 27.83%. By contrast, 9-ethyl-3-(9-phenyl-9H-fluoren-9-yl)-9H-carbazole (Et-PFCz), in which these hydrogen bond interactions are blocked, formed one-dimensional (1D) microbelts with larger molecular packing distances and its microcrystal films exhibited a PLQY of 52.21%, substantially exceeding that of its amorphous state (22.00%) and even that of its solution state (47.57%). These findings demonstrate that eliminating solvent-molecule hydrogen bonding is a powerful strategy to modulate molecular packing patterns and enhance the CLoSE effect, which provides valuable insights for the rational design of high-performance organic light-emitting materials and devices.

Stretchable alternating current electroluminescent (ACEL) devices that emit multiple colors are essential for soft electronics and displays. However, traditional ACEL devices face critical challenges in color tunability and stretchability. This study introduced tris(8-hydroxyquinolinato)aluminum (Alq 3) into the emitting layer for the construction of a multicolored ACEL device, which achieves color-tunable emissions from blue to red (464-588 nm) by adjusting the mass ratio of Alq 3 to ZnS-based phosphors. Polydimethylsiloxane was integrated as a flexible matrix and Ag nanowires as stretchable electrodes to endow the device with mechanical stretchability up to 240% while maintaining stable emission under 50% strain. Structural and photophysical characterizations have confirmed that the incorporation of Alq 3 does not affect the crystallinity of the phosphors but regulates emission through charge transfer. Patterned multicolor display arrays and a customizable ”CMSOD” emblem have been fabricated, highlighting potential applications in information displays. This work presents a straightforward method for fabricating stretchable ACEL devices with tunable color output through organic-inorganic hybrids, offering an alternative ACEL device for soft optoelectronics with colorful displays.

Stability against oxygen is an important factor affecting the performance of organic semiconductor devices. Improving photooxidation stability can prolong the service life of the device and maintain the mechanical and photoelectric properties of the device. Generally, various encapsulation methods from molecular structure to macroscopic device level are used to improve photooxidation stability. Here, we adopted a crystallization strategy to allow 14H-spiro[dibenzo[c,h]a-cridine-7,9′-uorene] (SFDBA) to pack tightly to resist fluo-rescence decay caused by oxidation. In this case, the inert group of SFDBA acts as a “steric armor”, protecting the photosensitive group from being attacked by oxygen. Therefore, compared with the fluorescence quenching of SFDBA powder under two hours of sunlight, SFDBA crystal can maintain its fluorescence emission for more than eight hours under the same conditions. Furthermore, the photolu-minescence quantum yields (PLQYs) of the crystalline film is 327.37 % higher than that of the amorphous film. It shows that the crystal-lization strategy is an effective method to resist oxidation.