Ján Garaj

Bio: Ján Garaj is an academic researcher from Comenius University in Bratislava. The author has contributed to research in topics: Copper & Crystal structure. The author has an hindex of 9, co-authored 50 publications receiving 406 citations.

Copper(ii) coordination compounds: classification and analysis of crystallographic and structural data iii. dimeric compounds

Abstract: This review summarizes the data for over nine hundred dimeric Cu(II) coordination compounds. There are several types of the bridges, from which doubly bridges by far prevail. The most common ligands are O− and N− donors. From the stereochemical point of view, a square-pyramidal arrangement with different degrees of distortion about Cu(II), is the most common. Several relationships were found between the Cu-Cu distances and the Cu-L-Cu bridge angle and the type of bridging, between the intra-ligand L-Cu-L ring angles and coordination numbers.

Perovskite solar cells with CuSCN hole extraction layers yield stabilized efficiencies greater than 20

Abstract: Perovskite solar cells (PSCs) with efficiencies greater than 20% have been realized only with expensive organic hole-transporting materials. We demonstrate PSCs that achieve stabilized efficiencies exceeding 20% with copper(I) thiocyanate (CuSCN) as the hole extraction layer. A fast solvent removal method enabled the creation of compact, highly conformal CuSCN layers that facilitate rapid carrier extraction and collection. The PSCs showed high thermal stability under long-term heating, although their operational stability was poor. This instability originated from potential-induced degradation of the CuSCN/Au contact. The addition of a conductive reduced graphene oxide spacer layer between CuSCN and gold allowed PSCs to retain >95% of their initial efficiency after aging at a maximum power point for 1000 hours under full solar intensity at 60°C. Under both continuous full-sun illumination and thermal stress, CuSCN-based devices surpassed the stability of spiro-OMeTAD–based PSCs.

Conductive metal–organic frameworks and networks: fact or fantasy?

Abstract: Electrical conduction is well understood in materials formed from inorganic or organic building blocks, but their combination to produce conductive hybrid frameworks and networks is an emerging and rapidly developing field of research. Self-assembling organic–inorganic compounds offer immense potential for functionalising material properties for a wide scope of applications including solar cells, light emitters, gas sensors and bipolar transparent conductors. The flexibility of combining two distinct material classes into a single solid-state system provides an almost infinite number of chemical and structural possibilities; however, there is currently no systematic approach established for designing new compositions and configurations with targeted electronic or optical properties. We review the current status in the field, in particular, the range of hybrid systems reported to date and the important role of materials modelling in the field. From theoretical arguments, the Mott insulator-to-metal transition should be possible in semiconducting metal–organic frameworks, but has yet to be observed. The question remains as to whether electro-active hybrid materials will evolve from chemical curiosities towards practical applications in the near term.

Hole‐Transporting Transistors and Circuits Based on the Transparent Inorganic Semiconductor Copper(I) Thiocyanate (CuSCN) Processed from Solution at Room Temperature

Abstract: The wide bandgap and highly transparent inorganic compound copper(I) thiocyanate (CuSCN) is used for the first time to fabricate p-type thin-film transistors processed from solution at room temperature. By combining CuSCN with the high-k relaxor ferroelectric polymeric dielectric P(VDF-TrFE-CFE), we demonstrate low-voltage transistors with hole mobilities on the order of 0.1 cm(2) V(-1) s(-1) . By integrating two CuSCN transistors, unipolar logic NOT gates are also demonstrated.

Vanadyl(IV) EPR Spin Probes Inorganic and Biochemical Aspects

Abstract: Many proteins have metal ions as an integral part of their structure or require them as cofactors in enzyme catalysis. In many cases, these metal ions serve as useful spectrochemical probes of molecular structure, electron transfer, and enzyme kinetics (Vallee and Williams, 1968; Vallee and Wacker, 1970; Ochiai, 1977; Hughes, 1972; Eichhorn and Marzilli, 1979). Often the native metal (frequently zinc) can be removed and another metal ion substituted which has different and sometimes more desirable spectroscopic properties. By judicious choice of substitute metal ion to match particular technique, e.g., nuclear magnetic resonance (NMR), Mossbauer, optical absorption, or electron paramagnetic resonance (EPR) spectroscopy, much can be learned about the metal binding site and its role in the function of the protein.