RESUMEN
The ability to craft the co-crystallization in conjugated polymer blends represents an important endeavor for the enhancement of charge transport. However, simple and efficient approaches to co-crystallization have yet to be realized. Herein, for the first time, a robust meniscus-assisted solution-shearing (MASS) strategy is reported to achieve co-crystallization in the poly(2,5-bis(3-hexylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT-C6) and poly(2,5-bis(3-decylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT-C10) blended films, and correlate this co-crystalline structure to the charge transport properties. The as-cast PBTTT-C6/PBTTT-C10 blends exhibit co-crystalline or phase-separated structures influenced by their molecular weights. Interestingly, confined-shearing of the initial phase-separated blended solution to MASS produces the formation of their co-crystallization. The co-crystallization kinetics accompanied by the chain packing change and optical properties are scrutinized. Finally, the resulting organic field-effect transistors (OFETs) signify the cocrystal-facilitated charge transport in the blends. Conceptually, this efficient MASS strategy in rendering the co-crystallization in conjugated polymer blends can be readily extended to other conjugated polymer blends of interest for a variety of device applications.
Asunto(s)
Menisco , Polímeros , Polímeros/química , Cristalización , Semiconductores , Tiofenos/químicaRESUMEN
The ability to enhance both the solvent and thermal stability of semiconducting π-conjugated polymers is highly desired for various device-related applications. Herein, a series of poly(3-hexylthiophene)-stat-poly[3-(6-hydroxy)hexylthiophene] (P3HT-stat-P3HHT) statistical copolymers with thermally cross-linkable hydroxyl groups is synthesized and their crystalline structures in three different states, solvent and thermal stability for use in organic field-effect transistors (OFETs) are elucidated. Importantly, these initial P3HT-stat-P3HHT thin films in their as-cast state crystallize well in an edge-on orientation. During annealing at 150 °C, these P3HT-stat-P3HHT occur cross-linked and retain edge-on orientation with increased crystallinity and ordering. In contrast, after high-temperature annealing at 300 °C, their edge-on orientation is significantly destroyed due to the cross-linking of hydroxyl groups at melted state. The correlation between different P3HT-stat-P3HHT and their charge mobilities is scrutinized. These cross-linked P3HT-stat-P3HHT exhibit good solvent resistance property and improved thermal stability in OFETs. Conceptually, such side-chain functionalization approach to improve the stability of P3HT-stat-P3HHT can be conveniently extended to other conjugated polymers for diverse optoelectronic applications.
RESUMEN
The ability to tune polymorphs of conjugated polymers affords a robust platform for investigating the processing-structure-property relationship. However, simple and generalizable routes to polymorphs have yet to be realized. Herein, we report a viable meniscus-assisted solution-shearing (MASS) strategy to effectively modulate polymorphs (i.e., polymorphs I and II) of poly(3-butylthiophene) (P3BT) and scrutinize the correlation between the two different polymorphs and charge transport characteristics. Specifically, polymorph II exists solely in drop-cast P3BT films. Intriguingly, confined shearing of P3BT renders efficient transformation of polymorph II to I. The kinetics of polymorph transformation associated with the changes in molecular packing and thus photophysical properties are elucidated. The resulting organic field-effect transistors reveal a strong correlation of device performance to attained polymorphs and crystal orientations of P3BT. Such polymorph transformation via the convenient MASS technique can be readily extended to other conjugated polymers of interest. This study highlights the robustness of MASS in regulating polymorphs of conjugated polymers to interrogate their interdependence of processing, structure, and property for a wide range of optoelectronic applications.
RESUMEN
A zirconium metallic organic framework UiO-66-NH2 has been synthesized and is further modified with imidazole-2-carboxaldehyde by a covalent post synthetic route which is based on a Schiff-base reaction. The as-prepared, functionalized MOF named UiO-66-NH2-IM is fully characterized. It retains its structural integrity during the PSM process and shows excellent luminescence and good fluorescence stability in water. It has also been further utilized as a sensitive fluorescent probe for sensing ions. The results show that UiO-66-NH2-IM can be developed into a highly selective and sensitive sensor for the detection of S2O82- (detection limit, 8.63 µM) and Fe3+ ions (detection limit, 4.95 µM) by fluorescence quenching of UiO-66-NH2-IM. All the possible mechanisms involved are discussed. Remarkably, it is the first covalent post-synthesized MOF to be developed as a colorimetric fluorescent sensor for the detection of S2O82- and Fe3+.
RESUMEN
A modified MOF named UiO-66-NH2-SA was synthesized based on the covalent post synthetic attachment of the MOFs (UiO-66-NH2) and salicylaldehyde via a Schiff-base reaction. The as-prepared functionalized UiO-66-NH2-SA not only maintains its structural integrity during the PSM process, but also shows excellent luminescence and good fluorescence stability in water. It was further utilized as a novel fluorescent probe for detecting of Al3+. The fluorescence intensity of UiO-66-NH2-SA increased linearly upon increasing the concentration of Al3+ in the range of 0-500 µM with a detection limit of 6.98 µM. The possible mechanism is discussed. This study presents a new ratiometric and colorimetric Al3+ fluorescent sensor. The good fluorescence stability of UiO-66-NH2-SA in aqueous media, the low detection limit and the broad linear in sensing Al3+ indicate its high potential in practical applications.