Researchers from the University of Twente (UT) managed to improve the conductivity of the best-known p-type transparent conductor, copper iodide (CuI). By adding a pinch of sulfur (S), conductivity improved by a factor of five while preserving 75 percent of transparency. The discovery could aid in the development of (semi)transparent electronic devices.
The thin films of CuI with sulfur were made with pulsed laser deposition. Sulfur induces defects in the material, which act like a source of free holes and contribute to the electrical conductivity of the material. Secondly, the high distribution of sulfur in grain boundaries leads to mixed phases in the material, which also contributes to increased conductivity.
To make transparent devices, both n and p-type conductors are needed. So far, however, the conductivity of p-type lags behind their n-type counterparts. That’s why the search is on to find a better-performing p-type conductor. “The high conductivities of the S:CuI films motivate further exploration of dopants and alloy strategies with CuI to achieve high-performing p-type transparent conductors,” the researchers write.