Cuprous Oxide is quite light sensitive and has an inherent speed similar to an ordinary enlarging paper.

You have to precipitate it in a special medium and then coat it. Processing uses ordinary dilute Sulfuric Acid. You can fix it with hypo. The emulsion is bright orange indicating that it is somewhat Ortho sensitive and the resulting image is a bit unstable and oxidizes rapidly in air. Toning is possible.

The details probably only appear in a Defensive Publication or a Research Disclosure. I don't believe any patents were filed.