Bi
2
Se
3
-based flexible thin film with high thermoelectric performance is promising for the waste heat recovery technology. In this work, a novel post-selenization method is employed to prepare ...n-type Bi
2
Se
3
flexible thin films with highly textured structure. The strengthened texture and Se vacancy optimization can be simultaneously achieved by optimizing the selenization temperature. The highly oriented texture leads to the increased carrier mobility and results in a high electric conductivity of ~ 290.47 S·cm
−1
at 623 K. Correspondingly, a high Seebeck coefficient (> 110 μW·K
−1
) is obtained due to the reduced carrier concentration, induced by optimizing vacancy engineering. Consequently, a high power factor of 3.49 μW·cm
−1
·K
−2
at 623 K has been achieved in as-prepared highly-bendable Bi
2
Se
3
flexible thin films selenized at 783 K. This study introduces an effective post-selenization method to tune the texture structure and vacancies of Bi
2
Se
3
flexible thin films, and correspondingly achieves high thermoelectric performance.
Graphical Abstract
Skutterudite CoSb3 material exhibits excellent thermoelectric properties for thermoelectric application. In this work, CoSb3 thin films were fabricated by direct current magnetron co-sputtering. The ...composition of thin films was controlled by regulating the deposition power of both Co and Sb. Then the as-deposited Sb-excess sample was chosen to process post-annealing. High-resolution transmission electron microscopy and X-ray diffraction, together with Raman analysis, demonstrate that the annealed samples have well-crystallized and nano-sized skutterudite CoSb3 structure. Hall measurement shows that specimens are P-type semiconductor. Both of the increasing of Seebeck coefficient and electric conductivity can be obtained when the samples annealed at appropriate temperature, indicating that thermally can improve its thermoelectric properties due to well-crystallized and nano-sized structure.
•The CoSb3 thin films were fabricated by direct current magnetron co-sputtering.•The films demonstrate well-crystallized and nano-sized skutterudite structure.•Nano-sized structures and weaker atomic vibration have benefit for S.•Thermally can improve thermoelectric properties with both increasing of S and σ.
A series traditional thermoelectric films, including n-type Bi, Bi
2
Te
3
, and p-type Sb, Sb
2
Te
3
, were synthesized with CH
3
NH
3
I by combining magnetron sputtering and thermal evaporation ...method. It is found that the Seebeck coefficients for all the composite films have enhanced although the electrical conductivities reduced due to the decreased carrier concentration. This leads to an obvious improvement of the power factor, especially for p-type Sb
2
Te
3
-based organic–inorganic hybrid films. As expected, a maximum power factor value around 2.3 mWm
−1
K
−2
has been achieved for the composition of Sb
2
Te
3
/CH
3
NH
3
I in range of the whole measured temperature, which is nearly seven times higher than that of pristine Sb
2
Te
3
film. By combination with the reduced thermal conductivity, a
ZT
value nearly 1.0 has been obtained at 380 K for the composition of Sb
2
Te
3
/CH
3
NH
3
I.
Thermoelectric thin film has attracted a lot of attention due to its potential in fabricating micropower generator in chip sensors for internet of things (IoT). However, the undeveloped performance ...of n-type thermoelectric thin film limits its widely application. In this work, a facile post-selenization diffusion reaction method is employed to introduce Se into Bi2Te3 thin films, in order to optimize the carrier transport properties. Experimental and theoretical calculation results indicate that the carrier concentration decreases and density of states increases after Se doping, leading to the enhancement of Seebeck coefficient. Further, adjusting the diffusion reaction temperature can maintain the carrier concentration while increasing the mobility simultaneously, resulting in a high power factor of 1.5 mW/(m·K2), which is eight times higher than that of the pristine Bi2Te3 thin films. Subsequently, a thin film device fabricated by the present Se-doped Bi2Te3 thin films shows the highest output power of 60.20 nW under the temperature difference of 37 K, indicating its potential for practical use.
Display omitted
•High-performance n-type Bi2Te3 based thin films were fabricated through a novel post-selenization diffusion reaction method.•Carrier concentration is precisely controlled by adjusting Se composition, leading to increase of Seebeck coefficient.•Optimization of post-selenization temperature, a high PF of 1.5 mW/(m·K2) is achieved, which was eight times of undoped film.•A fabricated thin film device shows the highest output power of 60.20 nW under the temperature difference of 37 K.
Zinc antimonide (Zn–Sb) is considered as a good candidate to replace the traditional TE materials due to its low cost, non-toxic, and high abundance of elements. In this work, layer-by-layer thin ...films were fabricated by sputtering Zn on the Sb precursor layer with a magnetron sputtering method, and an annealing process is performed on thin films to engage a self-assembled growth of Zn–Sb films. It is found that Zn–Sb film with good crystallinity was obtained after annealing at 300 ℃ for 10 min. Then, the influence of Zn layer thickness and annealing time on the structural, compositional, and thermoelectric properties for the Zn–Sb thin films were investigated. As a result, the thin film with mixed Zn
4
Sb
3
/ZnSb phases achieved a high power factor of 3.42 µWcm
−1
K
−2
when the Zn layer thickness was 600 nm. Additionally, the power factor was further optimized to 3.80 µWcm
−1
K
−2
after prolonging the annealing time up to 15 min.
In this work, using a conventional magnetron sputtering system, Al-doped ZnO (AZO) films with (112&cmb.macr;0) and (0002) preferential orientations were grown on
r
-sapphire and
a
-sapphire ...substrates, respectively. The effect of substrate and deposition temperature on the growth of AZO films and their preferential orientations were investigated. The crystallographic characteristics of AZO films were characterized by X-ray diffraction (XRD). The surface morphology of AZO films was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). It is found that the lattice mismatch between AZO and substrate determines the growth of AZO films and their preferential orientations. The thermoelectric properties are strongly dependent on the crystal grain shape and the grain boundaries induced by the preferred orientation. The highly connected and elongated grains lead to high thermoelectric properties. The in-plane anisotropy performances of thermoelectric characteristics were found in the (112&cmb.macr;0) preferential oriented ZnO films. The in-plane power factor of the (112&cmb.macr;0) preferential oriented ZnO films in the 0001 direction was more than 1.5 × 10
−3
W m
−1
K
−2
at 573 K, which is larger than that of the (0002) preferential oriented ZnO films.
In this work, using a conventional magnetron sputtering system, Al-doped ZnO (AZO) films with (112&cmb.macr;0) and (0002) preferential orientations were grown on
r
-sapphire and
a
-sapphire substrates, respectively.
•AZO thin films were deposited using the cost-effective and flexible design Zn–Al target.•AZO thin film has better thermoelectric properties at higher temperature.•The thermoelectric properties of ...AZO thin films enhance after changing the Al content.
Al-doped ZnO (AZO) has practical applications in the industry for thermoelectric generation, owing to its nontoxicity, low-cost and stability at high temperatures. In this study, AZO thin films with high quality were deposited on BK7 glass substrates at room-temperature by direct current reactive magnetron sputtering using Zn–Al alloy target. The deposited thin films were annealed at various temperatures ranging from 623K to 823K with a space of 50K. It is found that the absolute value of Seebeck coefficient of AZO thin film annealed at 723K increases stably with increasing of measuring temperature and reaches a value of ∼60μV/K at 575K. After that, Al-doping content was varied to further optimize the thermoelectric properties of AZO thin films. The power factor of AZO thin films with Al content of 3wt% increased with increase of measuring temperature and the maximum power factor of 1.54×10−4Wm−1K−2 was obtained at 550K with the maximum absolute values of Seebeck coefficient of 99μV/K, which is promising for high temperature thermoelectric application.
•An improvement in PF=S2σ of AZO thin film has been achieved by introducing Ti as a co-dopant with Al.•Ti4+ substituted for Zn2+ site rather than Al3+, which created extra electrons and the σ value ...at room temperature increased significantly.•S increased due to the increase of effective density of states by introducing multiple localized sub-bands.•The enhanced power factor of AZO films was discussed and strongly related to Ti co-doping.
A drastic improvement in the power factor of Al-doped ZnO (AZO) thin film was achieved by introducing Ti as a co-dopant with Al. A Ti super-thin buffer layer was firstly deposited on the glass substrate, and then AZO thin films were deposited onto Ti buffer layer at room-temperature. The introduction of Ti buffer layer facilitated the growth of AZO films and improved its crystallinity. XPS and XRD results showed that Ti4+ substituted for Zn2+ site, which created extra electrons. Dual doping of ZnO with Al and Ti drastically increased the electrical conductivity and the Seebeck coefficient of AZO films at high temperature. As a result, a significant enhanced power factor as high as 12.8×10−4Wm−1K−2 was achieved at 573K in Ti co-doped AZO films, which was more than 18 times larger than that of the films without Ti co-doping (0.64×10−4Wm−1K−2).
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