Superconductivity above 30 K in alkali-metal-doped hydrocarbon

Abstract

The recent discovery of superconductivity with a transition temperature (Tc) at 18 K in Kxpicene has extended the possibility of high-Tc superconductors in organic materials. Previous experience based on similar hydrocarbons, like alkali-metal doped phenanthrene, suggested that even higher transition temperatures might be achieved in alkali-metals or alkali-earth-metals doped such polycyclic-aromatic-hydrocarbons (PAHs), a large family of molecules composed of fused benzene rings. Here we report the discovery of high-Tc superconductivity at 33 K in K-doped 1,2:8,9-dibenzopentacene (C30H18). To our best knowledge, it is higher than any Tc reported previously for an organic superconductor under ambient pressure. This finding provides an indication that superconductivity at much higher temperature may be possible in such PAHs system and is worthy of further exploration.

Exciton properties of selected aromatic hydrocarbon systems

“…1 lower panel. The latter have received increasing attention recently due to the observation of superconductivity in alkali doped hydrocarbon crystals, among them picene, with relatively high transition temperatures to the superconducting state [10][11][12][13][14][15]. In all cases the molecules in the solid arrange in a herringbone manner which is typical for many aromatic hydrocarbon molecular solids and can be seen as a consequence of the densest possible packing of the molecules within the crystal with the least possible repulsion.…”

Redox-controlled potassium intercalation into two polyaromatic hydrocarbon solids

“…7 Reaction of potassium with picene (C22H14), a phenacene composed of five fused benzene rings, has been reported to afford superconductivity at 18 K. 8 Superconductivity in other alkali-metal polyaromatic hydrocarbons (PAHs) was subsequently reported in phenanthrene-, dibenzopentacene-and coronene-based materials, with the highest reported Tc of 33 K claimed 2 in potassium-doped 1,2:8,9-dibenzopentacene. [9][10][11] Despite the significant interest in these materials, to date no crystal structure has been determined for any of the alkali-metal PAH systems. This structural information is a prerequisite for materials design and for understanding of both physical properties and reaction chemistry.…”

“…[9][10][11] Despite the significant interest in these materials, to date no crystal structure has been determined for any of the alkali-metal PAH systems. This structural information is a prerequisite for materials design and for understanding of both physical properties and reaction chemistry.…”

Hybridized electronic states in potassium-doped picene probed by soft x-ray spectroscopies

“…Before the K L 3 resonance (hν in = 292.2 eV), the XES feature at hν out = 285 eV (around E F ) weakly appears. This feature is enhanced at the K L 3 and L 2 resonances (hν in = 295.8 and 298.6 eV, respectively), as well as the K 3s → 2p peak. These spectral change by the resonant excitation can be found more clearly in the difference spectra subtracted by the non-resonant spectra measured at hν in = 292.2 eV.…”

“…2, 3 In order to elucidate the nature of the superconductivity, detailed information on the electronic structure near the Fermi energy (E F ) has been required. From theoretical investigations, it has been suggested for K-doped picene that the dopant (K) outer orbitals are weakly hybridized with the electronic states of picene close to E F , which plays a crucial role in the superconductivity.…”