Preparation And Properties Of N-type Bi₂Te₃/CH₃NH₃I Organic-Inorganic Composite Thermoelectric Thin Films

As one of low temperature thermoelectric materials,bismuth telluride based compounds have the best performance currently,and it has been used in a number of areas such as aerospace,medical appliance,microelectronic devices,biologic slug and so on.In recent years,studies have shown that low dimensional thermoelectric materials can enhance the electronic density of states near Fermi level and nanostructured thermoelectric materials have a large quantity of boundaries that will strongly scatter the phonons and carries.Therefore the Seebeck coefficient is improved,the thermal conductivity reduced,and the thermoelectric properties improved.As a kind of crystallization,non-toxic,low cost organic material,CH₃NH₃I is used to prepared various material which have good performance such as the optical absorption layer,perovskite material and various luminescent materials.Moreover the related research also shows that use organic materials hybrid into inorganic materials can reduce the thermal conductivity of thermoelectric materials.It has become one of the hotspots in the field of thermoelectric materials in recent years.So,in this paper it has been used to prepare various kinds of organic inorganic composite thermoelectric materials to improve the properties of thermoelectric materials.In this paper,the N type Bi₂Te₃/CH₃NH₃I composite thin films were prepared by physical vapor deposition,and the effects of preparation process and iodine content on the thermoelectric properties were investigated.The main researchs are as follows:?1?The N type Bi/CH₃NH₃I and P type Sb/CH₃NH₃I composite thin films were prepared by magnetron sputtering and thermal evaporation.The study found that Bi/CH₃NH₃I samples all the Seebeck coefficient and electrical conductivity decrease.The conductivity of Sb/CH₃NH₃I composite thin films was not improved,but the Seebeck coefficient was improved obviously,the thermoelectric properties of Sb/CH₃NH₃I composite were improved.?2?N type Bi₂Te₃/CH₃NH₃I thin films were also prepared by magnetron sputteringand thermal evaporation.It is found that the conductivity of the Bi₂Te₃/CH₃NH₃I thin films is reduced,but the Seebeck coefficient is improved obviously.When the test temperature is 190? the I content is 8.83% sample have maximum Seebeck coefficient-245.5 ?VK-1 and the maximum power factor of 3.5×10-3 Wm-1K-2.?3?N type Bi₂Te₃/CH₃NH₃I thin films were prepared by evaporation layer by layer.The results show that the conductivity and the Seebeck coefficient of Bi₂Te₃/CH₃NH₃I thin films are both improved.Sample of 0.54% I content the power factor reach up to2.8×10-3 Wm-1K-2 at 110? test temperature.?4?N type Bi₂Te₃/CH₃NH₃I thin films were prepared by co-evaporation,The study found that iodine content of 2.52% samples the Seebeck coefficient is-197.9?VK-1 at room temperature,the power factor is 6.5×10-4WK-2m-1,and the Seebeck coefficient up to-300.1?VK-1 at 110? test temperature,the power factor can reach to2.2×10-3WK-2m-1.