Preparation And Properties Of P-type Sb₂Te₃-CH₃NH₃I Organic-Inorganic Composite Thermoelectric Thin Films

Thermoelectric materials are environment friendly materials,which can convert heat into electricity and have broad application prospects.In recent years,the study of thermoelectric materials found compositing and thinning can help to improve the thermoelectric properties.A new way to improve the thermoelectric figure of merit was to combine the materials with low thermal conductivity and good electrical properties.While keeping the low thermal conductivity and doesn't affect the electrical properties of the material.Sb₂Te₃ as one of the thermoelectric materials with large Seebeck coefficient,moderate conductivity and low thermal conductivity near room temperature.CH3NH3 I as an organic matter has the advantages of crystallization,non-poisonous,low cost.Further more CH3NH3 I as light absorbing layer could effectively improve the photoelectric conversion efficiency of solar cells.In this paper the inorganic-organic hybrid Sb₂Te₃-CH₃NH₃I thin film was deposited by radio frequency magnetron sputtering and thermal evaporation system.The effect of preparation method,substrate material,organic content and post-annealing on the microstructure and the thermoelectric properties were investigated.The specific research contents are as follows:Firstly,the BK7 glass and polyimide flexible substrates were selected to deposit organic-inorganic composite films.The effects of organic contents and post-annealing on the structure and thermoelectric properties of the composite films were investigated,It was found that P type Sb₂Te₃-CH₃NH₃I samples show much more enhanced power factor than that of Sb₂Te₃ thin film?1.13×10-3 Wm-1K-2?.P type Sb₂Te₃-CH₃NH₃I?0.76 at.%?annealed at 523 K showed a maximum power factor of8.10×10-3Wm-1K-2at the measured temperature of 383 K.Sample with 423 K low temperature annealing has poor crystallization,many defects and lower power factor?2.05×10-4 Wm-1K-2?.However,when the annealing temperature was 473 K,the power factors was improved.The maximum power factor 8.53×10-3W/mK2 was measured atmeasured temperature 383 K.Secondly,P type Sb₂Te₃-CH₃NH₃I organic-inorganic hybrid thermoelectric thin films were deposited only by thermal evaporation technique,and the effects of post-annealing on the structure and thermoelectric properties were investigated.Results show that the sample annealing at 423 K has poor crystallization and thermoelectric properties.However when the annealing temperature increased to473 K,sample crystallization was obviously improved,but surface structural defects are also serious.When the sample was annealed at 448 K the maximum power factor reach at 1.68×10-3 W/m K2.In conclusion,this work provided the preliminary theory and technical assistance to fabricate the inorganic-organic thermoelectric thin film with good performance.