دانلود کتاب پلیمرها و سیستم های ترموالکتریک انعطاف پذیر

Thermoelectric materials are interesting because they can be used to directly convert heat into electricity. Some conductive materials can exhibit a notable voltage under temperature gradient, that is, the Seebeck effect. The thermovoltage with respect to the temperature is called Seebeck voltage. The Seebeck voltage can be positive or negative depending on the accumulation of the charge carrier(s) at the two ends under temperature gradient. A p-type thermoelectric material exhibits a positive Seebeck voltage, while an n-type thermoelectric material has a negative Seebeck voltage. High Seebeck coefficient has been observed on semiconductors and semimetals. The value is related to the relative position of the Fermi level from the top of the valence band or the bottom of the conduction band or simply the doping level since a change in the doping level can shift the Fermi level. Apart from the Seebeck coefficient, a high electrical conductivity is also required for efficient thermoelectric conversion. However, a good thermoelectric material should have a low thermal conductivity so that more heat can be utilized for power generation. Thermoelectric materials are used as the active materials of thermoelectric generators. They can be used in thermoelectric cooling systems in terms of the Peltier effect as well. The conventional thermoelectric materials are inorganic semiconductors or semimetals such as Bi2Te3 and its derivatives or analogues. These materials can exhibit high Seebeck coefficient and high electrical conductivity, but they also have a problem of high thermal conductivity. Hence, great effort has been made on lowering the thermal conductivity of inorganic thermoelectric materials besides on the improvement in the Seebeck coefficient and/or electrical conductivity. Consider for practical application, inorganic thermoelectric materials are usually brittle, and thus they are not suitable for flexible thermoelectric systems.