Or, just go with PV that tolerates higher temperature better. GaAs PV cells are used in some satellites for this reason, I think. Here on Earth, CdTe is used in place of Si in some hotter environments for this reason as well. CdTe has the advantage of being extremely thin (the absorption length of photons in the material is something like 0.1 microns) which could be an advantage in space, where the PV arrays could be deployed as extremely thin sheets, much thinner than modules on the ground that have to stand up to wind, rain, and gravity.
i was thinking carborundum, diamond, or materials that aren't even semiconductors at room temperature, like zirconia. i don't think cadmium telluride will survive sunlight at the orbital radius of mercury, but plainly some solids do
