You can't reach 25% efficiency with monocrystalline silicon PV even with the entire industrial economy backing you up; those efficiencies require multijunction solar cells. Conveniently homebrewable PV panels, like the ZnO:Mg/Cu2O cells you link below, are closer to 1% efficient. The author reports 525mV and 0.9mA/cm², which works out to 4.7W/m², which would be 0.5% efficient if the illumination is one sun.
They probably are a better approach than the thermoelectric approach, because not only are they more efficient, they use more abundant materials and thinner films of them. But either approach could plausibly defeat the other.
Longi has demonstrated a champion monocrystalline silicon cell at 27.3% efficiency and it has silicon cells over 26% efficiency in mass production. It has demonstrated a champion silicon module at 25.4% efficiency.
They probably are a better approach than the thermoelectric approach, because not only are they more efficient, they use more abundant materials and thinner films of them. But either approach could plausibly defeat the other.