Effect of imidazolium-based ionic liquids on the nanoscale morphology of CuTCNQ (TCNQ = 7,7,8,8-tetracyanoquinodimethane) metal-organic semiconductors

Surface Morphology and Electrical Properties of Cu3BTC2 Thin Films Before and After Reaction with TCNQ

HKUST-1 or Cu₃BTC₂ (BTC = 1,3,5-benzenetricarboxylate) is a prototypical metal-organic framework (MOF) that holds a privileged position among MOFs for device applications, as it can be deposited as thin films on various substrates and surfaces. Recently, new potential applications in electronics have emerged for this material when HKUST-1 was demonstrated to become electrically conductive upon infiltration with 7,7,8,8-tetracyanoquinodimethane (TCNQ). However, the factors that control the morphology and reactivity of the thin films are unknown. Here, we present a study of the thin-film growth process on indium tin oxide and amorphous Si prior to infiltration. From the unusual bimodal, non-log-normal distribution of crystal domain sizes, we conclude that the nucleation of new layers of Cu₃BTC₂ is greatly enhanced by surface defects and thus difficult to control. We then show that these films can react with methanolic TCNQ solutions to form dense films of the coordination polymer Cu(TCNQ). This chemical conversion is accompanied by dramatic changes in surface morphology, from a surface dominated by truncated octahedra to randomly oriented thin platelets. The change in morphology suggests that the chemical reaction occurs in the liquid phase and is independent of the starting surface morphology. The chemical transformation is accompanied by 10 orders of magnitude change in electrical conductivity, from <10^-11 S/cm for the parent Cu₃BTC₂ material to 10^-1 S/cm for the resulting Cu(TCNQ) film. The conversion of Cu₃BTC₂ films, which can be grown and patterned on a variety of (nonplanar) substrates, to Cu(TCNQ) opens the door for the facile fabrication of more complex electronic devices.

S,N-Containing Co-MOF derived Co9S8@S,N-doped carbon materials as efficient oxygen electrocatalysts and supercapacitor electrode materials

Co₉S₈@S,N-doped carbon materials derived from S,N-containing Co-MOFs exhibited superior performance as bifunctional oxygen electrocatalysts and supercapacitor electrode materials.

Conductive casting films based on an octasilicate-core dendrimer containing the mixed-valence state TCNQ on the periphery

An imidazolium–TCNQ anion radical terminated octasilicate (OS)-core dendrimer was synthesized to form conductive films by casting with the neutral TCNQ.

Low-temperature fabrication of alkali metal-organic charge transfer complexes on cotton textile for optoelectronics and gas sensing

A generalized low-temperature approach for fabricating high aspect ratio nanorod arrays of alkali metal-TCNQ (7,7,8,8-tetracyanoquinodimethane) charge transfer complexes at 140 °C is demonstrated. This facile approach overcomes the current limitation associated with fabrication of alkali metal-TCNQ complexes that are based on physical vapor deposition processes and typically require an excess of 800 °C. The compatibility of soft substrates with the proposed low-temperature route allows direct fabrication of NaTCNQ and LiTCNQ nanoarrays on individual cotton threads interwoven within the 3D matrix of textiles. The applicability of these textile-supported TCNQ-based organic charge transfer complexes toward optoelectronics and gas sensing applications is established.

Ionic liquid mediated synthesis of nitrogen, carbon and fluorine-codoped rutile TiO2 nanorods for improved UV and visible light photocatalysis

The application of [BMIM][BF₄] ionic liquid as a designer solvent for the synthesis of multiple nonmetals-codoped rutile titania nanorods is presented. These nanorods show remarkable photoactivity under UV and visble light conditions.