Sheet resistance was measured with a collinear fourpoint probe directly contacting the film. The Seebeck coefficient of a CuP 2 film on glass was measured in a custom-built setup using In contacts. The work function was measured with a Kelvin probe calibrated with a standard Au sample. Absorption coefficient and optical functions were extracted by spectroscopic ellipsometry. Due to higher porosity in the upper part of the film, we modeled the system as a glass substrate of known optical functions, a CuP 2 layer with a linearly increasing fraction of air from bottom to top, and a roughness layer treated with Bruggeman effective medium theory.