Thermoelectric Coefficients: Nanoribbon

[MGNano]

What is the significance of negative seebeck and peltier coefficients for a bulk nanoribbon system?
Also what does low/high values of these coefficients signify for the same system?

[kstokbro]

Please check:
http://www.quantumwise.com/documents/tutorials/latest/Phonon/index.html/
however, it is related to the sign of the bias differen when you have a temperature difference between the two electrodes.