For semiconductors, the Arrhenius equation ρ = ρ 0 exp( Ea k B T ) holds. The straight blue line fits part of the ln (ρ) vs. 1/T curve (red). From the slope of the blue line, the activation energy E a was determined to be E a = 5.4 meV. This is a very small number, much less than the PBE-DFT calculated 1 eV. Once again, this may suggest the existence of defect electronic energy levels in the band gap. The difference of the activation energy with the theoretical band gap of our triclinic NbSe 2 I 2 is larger than other van der Waals materials, such as MoS 2 , 72 but it is also known that degradation can considerably lower the activation energy, as in the case of WTe 2 . Thermal measurements below room temperature were also conducted, with DSC and PPMS heat capacity, with data shown in Figure S6, 39 and there were no phase transitions detected for NbSe 2 I 2 . Magnetic measurements verified that triclinic NbSe 2 I 2 is indeed diamagnetic, and the magnetization (M ) vs. field (H) curves are shown in Figure .