Abstract
Potassium-doped picene (picene) has recently been reported to be a superconductor at with critical temperatures up to 18 K. Here we study the electronic structure of K-doped picene films by photoelectron spectroscopy and ab initio density functional theory combined with dynamical mean-field theory (). Experimentally we observe that, except for spurious spectral weight due to the lack of a homogeneous chemical potential at low K concentrations (), the spectra always display a finite energy gap. This result is supported by our calculations which provide clear evidence that picene is a Mott insulator for integer doping concentrations , 2, and 3. We discuss various scenarios to understand the discrepancies with previous reports of superconductivity and metallic behavior.
- Received 15 October 2012
DOI:https://doi.org/10.1103/PhysRevLett.110.216403
© 2013 American Physical Society