  We investigated the material parameters of several single-layer cuprates,
including those with fluorinated buffer layers, with the aim of identifying
possible high-temperature superconductors. To evaluate the material parameters,
we use the Wannierization techniques and the constrained random phase
approximation. The obtained single-band Hubbard models are studied using the
fluctuation-exchange approximation. Comparison among several cuprates reveals
unknown high-$T_{\text{c}}$ superconductors. In, Ga, Al, and Cd compounds in
particular show the potential to exhibit higher-$T_{\text{c}}$
superconductivity than Hg1201.
