It sounds like you want a voltage inverter. The one in the link uses a 7660s, which has a maximum input voltage of 13V. I believe you can swap the 7660s for an LT1054, which has a maximum input voltage of 16V.
To verify that the LT1054 is compatible in the circuit, you can compare their datasheets and do a google search for "LT1054 voltage inverter schematic" and "7660s voltage inverter schematic", and then compare the circuits, ... , or you can just build the thing on a breadboard and see if it works.
Incidentally, what are you using this for? You have other options here, but whether they will be useful depends on the details of your project (output voltage precision and current capacity requirements, input PSU current capacity, what circuits will you be powering, etc).