First-principles calculations on the diffusion and electronic properties of CuI doped by cation and anion

CuI has attracted much attention for the optoelectronic devices due to the wide band gap of 3.1 eV (p-type). Previous theoretical and experimental results demonstrate doping successfully tunes stability of the intrinsic defects in CuI. We study the diffusion and electronic properties of CuI doped with Li, Na, Mg, F, Cl, and Br using first-principles calculations. Importantly, the low diffusion energy barriers (<0.6 eV) enable uniform distribution of the dopants. Br, Cl, and F at the I site reduce the band gap to 1.08, 1.06, and 1.00 eV as compared to 1.09 eV for undoped CuI. The anion at the interstitial site introduces some unoccupied states at 0.06 eV above the valence band maximum, enhancing the p-type conductivities.

Automated summary

CuI has gained attention for optoelectronic devices because of its wide band gap. This study investigates the diffusion and electronic properties of CuI doped with various elements using first-principles calculations. Doping with Br, Cl, and F significantly reduces the band gap, and anion at the interstitial site introduces unoccupied states, enhancing p-type conductivity.