I’m not sure what they mean by “traditional materials” here, but from their paper the COP is in the range of 1.3 - 6.8 depending on heat load which is similar to a modern household refrigerator. So yeah, it really does seem to be good enough to replace mechanical cooling.

The paper also references a Samsung hybrid refrigerator that already uses a thermoelectric device to improve efficiency (probably by letting the compressor operate in a more efficient mode most of the time).

According to the paper Samsung uses a bulk TEC device with a COP of 1.2 - 3 depending on heat load. That’s already fairly close to mechanical cooling. If it wasn’t it wouldn’t have made sense for Samsung to use it in a refrigerator whose whole selling point is efficiency.

I mean, clearly the 100% improvement is for the high heat load COP relative to that Samsung device, right? From 3 to 6.. and I think 6 is better than most commercially viable mechanical cooling solutions, no?