Preparation and thermoelectric properties of N type Ag2Te@PEDOT:PSS composite films
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摘要: 利用一步热还原法制备了聚3, 4-乙烯二氧噻吩:聚苯乙烯磺酸包覆的Te纳米线(Te@PEDOT:PSS)复合膜,然后将其浸入不同浓度的AgNO3溶液中,通过Ag+与Te的反应使Te向Ag2Te转变,从而使热电材料由P型的Te@PEDOT:PSS复合膜转化为N型的Ag2Te@PEDOT:PSS复合膜。通过FESEM、TEM、XPS、XRD等表征手段揭示了掺杂过程中AgNO3与Te@PEDOT:PSS复合膜的作用机制,探究了掺杂浓度对Ag2Te@PEDOT:PSS复合膜热电性能的影响。反应中Ag2Te@PEDOT:PSS复合膜的电导率随着AgNO3溶液浓度的增加呈先增大后减小的趋势,主要是由于AgNO3浓度较大时生成TeO2造成的,Seebeck系数随着AgNO3浓度增大而迅速减小,主要是由于反应生成的Ag2Te为N型传导,当Ag2Te所提供的电子数量超过Te提供的空穴数量时,材料的传导机制由P型变为N型,即Seebeck系数由正变负,随着AgNO3浓度的增大,Seebeck系数的绝对值变大,当AgNO3溶液浓度为10 mmol时,Seebeck系数为(−55.9±3.3) μV/K。当AgNO3溶液浓度为20 mmol时,N型Ag2Te@PEDOT:PSS复合膜的功率因子达最大值,为(8.4±0.7) μW/(m·K2)。Abstract: The poly(3,4-ethyl-enedioxythiophene): polystyrenesulfonate functionalized Te nanowires (Te@PEDOT:PSS) composite films were in situ synthesized using a one-step thermal reduction process. Then the Te@PEDOT:PSS composite films were immersed into AgNO3 solutions with different concentration to prepare Ag2Te@PEDOT:PSS composite films. By introducing Ag+ into the Te@PEDOT:PSS composite films, P type Te@PEDOT:PSS composite films was transformed to N type Ag2Te@PEDOT:PSS composite films. FESEM, TEM, XPS, and XRD were used to analysis the reaction mechanism between AgNO3 and Te@PEDOT:PSS composite films. Also, the thermoelectric properties of the Ag2Te@PEDOT:PSS composite films as a function of AgNO3 concentration were measured. The electrical conductivity of Ag2Te@PEDOT:PSS composite films first increases as the increasing AgNO3 concentration, and then decreases due to the formation of TeO2. The Seebeck coefficient of the Ag2Te@PEDOT:PSS composite films decreases significantly with the increasing concentration of AgNO3. The phenomenon can be contributed to the N type conduction of Ag2Te, and when the amount of electron provided by Ag2Te is larger than the amount of hole from Te, the conduction mechanism changes from P type to N type. As the further increasing concentration of AgNO3, the absolute value of Seebeck coefficient of the Ag2Te@PEDOT:PSS composite films increases. And the value reaches (−55.9±3.3) μV/K when the concentration of AgNO3 is 10 mmol. The N type Ag2Te@PEDOT:PSS composite film shows a maximum power factor of (8.4±0.7) μW/(m·K2) with 20 mmol AgNO3.
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Key words:
- PEDOT:PSS /
- Ag2Te /
- composites /
- thermoelectric properties /
- film /
- Seebeck coefficient
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图 1 聚3, 4-乙烯二氧噻吩:聚苯乙烯磺酸包覆的Te纳米线(Te@PEDOT:PSS)复合膜及不同AgNO3浓度的Ag2Te@PEDOT:PSS复合膜的FESEM图像: (a) Te@PEDOT:PSS; (b) 0.1 mmol AgNO3; (c) 5 mmol AgNO3; (d) 10 mmol AgNO3
Figure 1. FESEM images of poly(3,4-ethyl-enedioxythiophene): polystyrenesulfonate functionalized Te nanowires (Te@PEDOT:PSS) composite film and Ag2Te@PEDOT:PSS composite films immersed in different concentration of AgNO3:(a) Te@PEDOT:PSS; (b) 0.1 mmol AgNO3; (c) 5 mmol AgNO3; (d) 10 mmol AgNO3
图 4 Te@PEDOT:PSS复合膜(a)和不同浓度AgNO3溶液掺杂后Ag2Te@PEDOT:PSS复合膜((b) 0.1 mmol AgNO3, (c) 5 mmol AgNO3,(d) 10 mmol AgNO3)的TEM图像及不同浓度AgNO3溶液掺杂后Ag2Te@PEDOT:PSS复合膜的EDS图谱((e) 0.1 mmol AgNO3, (f) 5 mmol AgNO3, (g) 10 mmol AgNO3; 对应 TEM图像中(b), (c), (d)的圈内成分)
Figure 4. TEM images of Te@PEDOT:PSS composite film (a) and Ag2Te@PEDOT:PSS composite films doped by AgNO3 with different concentration ((b) 0.1 mmol AgNO3, (c) 5 mmol AgNO3, (d) 10 mmol AgNO3) and EDS spectra of Ag2Te@PEDOT:PSS composite films doped by AgNO3 with different concentration ((e) 0.1 mmol AgNO3, (f) 5 mmol AgNO3, (g) 10 mmol AgNO3; Corresponding to circle part of TEM images in (b), (c) and (d))
表 1 5 mmol AgNO3浸泡后Ag2Te@PEDOT:PSS复合膜表层结晶物元素含量
Table 1. Element contents of crystal on surface of Ag2Te@ PEDOT:PSS composite film immersed in 5 mmol AgNO3
Element Mass fraction/% Atomic fraction/% O 7.80 40.10 Ag 3.95 3.01 Te 88.25 56.89 表 2 0.1 mmol AgNO3浸泡后Ag2Te@PEDOT:PSS复合膜的元素含量
Table 2. Element contents of Ag2Te@PEDOT:PSS composite film immersed in 0.1 mmol AgNO3
Element Mass fraction/% Atomic fraction/% S 0.5 2.1 Ag 2.8 3.3 Te 96.6 94.6 表 3 5 mmol AgNO3浸泡后Ag2Te@PEDOT:PSS复合膜的元素含量
Table 3. Element contents of Ag2Te@PEDOT:PSS composite film immersed in 5 mmol AgNO3
Element Mass fraction/% Atomic fraction/% S 0.4 1.5 Ag 57.6 60.9 Te 42.0 37.6 表 4 10 mmol AgNO3浸泡后Ag2Te@PEDOT:PSS复合膜的元素含量
Table 4. Element contents of Ag2Te@PEDOT:PSS composite film immersed in 10 mmol AgNO3
Element Mass fraction/% Atomic fraction/% S 0.3 1.0 Ag 59.9 63.4 Te 39.9 35.7 -
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