[gus_massa]

This adds weight and volume that are bad for a mobile phone. Also, the size must be enough to process all the heat from the phone. In systems with a big heatsink you will need a bigger device between the heat source and the heatsink. This will not be a problem for phones, but it may be a problem for notebooks.

Also, with a difference of 30C (60F) they increased the maximum efficiency from 1% to 4%, but that temperature difference is probably too hot for a phone in your pocket.

It's probably better to have a smaller phone, or to use the additional space/weight in a bigger battery.