Why there is no paper optimize the consumption power of the circuit in energy harvest?
Everyone wants to minimize the power of their circuits, so there's nothing special about energy harvesting devices, at all.

Also, every paper about making communications more reliable while is about making the power usage lower, simply because if you want constant reliability, you can then achieve that with lower power.

Basically, all the research on transmitters  uses the energy per bit as the critical measure, so you really don't need to look for energy harvesting-specific papers.

So, this really boils down to basic textbook knowledge of transmitter design, not to speciality papers.

Now, that's on the theoretical side of things. When it comes to building silicon doing the things that you derived are good in theory, then you'll find that modern silicon's manufacturing techniques are very much limited by the power consumption of devices – so, the secrets that you're asking for a worth billions of Qualcomm's, Apple's, ZTE's, and (formerly) intel's money.