Discovery of Sodium-Doped Triphenylene Superconductors by Searching the Organic Material Database

Abstract

Over the past few decades, there has been a lot of research on organic molecule-based materials for future advanced technology. The superconductivity has also been reported in various carbon-based organic materials in line with this trend. In particular, polycyclic aromatic hydrocarbons (PAHs) have been intensively studied in recent years because of the highly conjugated characteristics of the delocalized electrons supplied by alkali metal doping. Here, we report on a PAH superconductor, sodium-doped triphenylene (nominal composition of Na 3 triphenylene), which was discovered by searching the database of PAH molecules with a small energy difference between the lowest unoccupied molecular orbital (LUMO) and LUMO + 1 states. As the first sodium-doped PAH superconductor, it shows the superconducting transition at T c ≈ 15 K under ambient pressure. The discovery of the new PAH superconductor suggests the promising possibility of superconductivity from more diverse molecular structures and the realization of high-T c organic superconductors furthermore.

Organic quantum materials: A review

“…Modern simulation tech is a solid stool to advance the development of SCs. Yoon et al 138 innovatively applied a computational method to pick AH candidates for the SC preparation, and successfully obtained a superconductive phase of Na 3 triphenylene. A small split may be necessary between the lowest unoccupied molecular orbital (LUMO) and LUMO + 1 for the emergence of superconductivity.…”

“…(A) Energy difference Δ of 200 AH molecules from the database, (B) Stacking type of filtered molecules with Δ lower than 0.2 eV, (C) Molecular structure of final 10 candidates. Reproduced with permission: Copyright 2020, American Chemical Society 138 …”

“…Casula et al 148 suggested that three phonons (intramolecular, intermolecular, and intercalant phonons) contributed to λ. In K 3 picene, 20% of λ came from 138 local contributions of pure molecules, and the remaining was from nonlocal couplings. 149 Mott transition in the solid with a sizeable U/W ratio indicated strong electron correlation, explained by the formation of 5% volume expansion by local magnetic moment.…”

Structural and Magnetic Properties of Potassium-Doped 2,3-DiMethylnaphthalene

“…The recrystallized samples may have lower crystallinity than the pristine sample. This is a common feature of most of doped PAHs materials [16,25,28]. Our analysis is mainly based on the position and relative strength of the major peaks.…”

“…The antiferromagnetic coupling in phase-pure crystal of [K(222)] 2 [p-terphenyl 3 ] that occurs in all three crystallographic directions was described by experimental results and density functional theory calculations [26]. The band structures of optimized Na 3 triphenylene crystal showed that the insertion of sodium atoms causes the material to change into metal [28].…”