Effect of native defects on thermoelectric properties of copper iodide films

Murmu, Peter P.; Karthik, V.; Chong, Shen V.; Rubanov, Sergey; Liu, Zihang; Mori, Takao; Yi, Jiabao; Kennedy, John

doi:10.1007/s42247-021-00190-w

Cited by 31 publications

(22 citation statements)

References 42 publications

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“…In contrast to our findings, Murmu et al have reported a very large Seebeck coefficient, 561.8 μV/K at 300 K. 46 They attributed this large value to the energy filtering effect occurring due to the potential barrier, which is formed by neutral Cu atoms precipitated to the grain boundary region through iodine loss during annealing. This may be the reason for the rather low hole concentration, 1.6 × 10 19 cm −3 , and the low electrical conductivity, 1.18 × 10 3 S/m.…”

Section: ■ Results and Discussioncontrasting

confidence: 99%

CuI: A Promising Halide for Thermoelectric Applications below 373 K

Almasoudi

Saeed

Salah

et al. 2022

ACS Appl. Energy Mater.

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Highly transparent p-type γ-CuI thin films with enhanced thermoelectric (TE) properties were produced by the pulsed laser deposition (PLD) technique. The film composed of fine nanoparticles was found to show transparency close to 90% and excellent TE performance at 300–360 K. Postannealing at three different temperatures in the range of 373–573 K in a vacuum was found to diminish the deviation from the stoichiometric composition, namely, δ in Cu1−δI, possibly due to iodine evaporation. The carrier (hole) concentration decreased and the Hall mobility increased on increasing the postannealing temperature, i.e., by decreasing δ. The film postannealed at 373 K showed the best TE performance with a high electrical conductivity of ∼14 000 S/m, a large Seebeck coefficient of ∼350 μV/K, and a high power factor of ∼1600 μW/(m K2) at 300 K. The degeneracy of the heavy- and light-hole bands of γ-CuI could enhance the Seebeck coefficient through enhancing the effective mass of holes and decreasing the carrier concentration, while electrical conductivity was only slightly decreased. Thermal conductivity of the γ-CuI thin films was verified to be as low as 0.77–0.83 W/(m K) at 300 K. The present study firmly demonstrates the high potential of the γ-CuI thin film as a p-type TE material to be paired with an n-type material for flexible TE devices and self-powered electronic systems operating at 300–360 K.

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Section: ■ Results and Discussioncontrasting

confidence: 99%

CuI: A Promising Halide for Thermoelectric Applications below 373 K

Almasoudi

Saeed

Salah

et al. 2022

ACS Appl. Energy Mater.

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“…Further, the vacuum-annealed CuI films presented the Hall mobilities of 6.1, 6.9, and 7.9 cm 2 /V·s and carrier concentrations of 5.6 × 10 19 , 4.3 × 10 19 , and 3.9 × 10 19 cm –3 annealed at temperatures of 100, 200, and 300 °C, respectively, exhibiting the increased Hall mobility and decreased carrier concentration. This is consistent with previous reports exhibiting the decreased hole concentration and increased Hall mobility of the CuI thin films with increasing vacuum annealing temperature, which can be attributed to the escape of iodine having a higher vapor pressure than copper from the film and decreased Cu vacancies, where the decrease in numbers of scattering centers increases the Hall mobility. , …”

Section: Resultssupporting

confidence: 93%

Synthesis of Vacancy-Controlled Copper Iodide Semiconductor for High-Performance p-Type Thin-Film Transistors

Lee

Yatsu

Kim

et al. 2022

ACS Appl. Mater. Interfaces

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Copper iodide (CuI) has emerged as a promising p-type semiconductor material owing to its excellent carrier mobility, high transparency, and solution processability. Although CuI has potential for numerous applications, including perovskite solar cells, photovoltaic devices, and thin-film transistors (TFTs), the close relationship between the anion vacancy generation and the charge transport mechanism in CuI-based devices is underexplored. In this study, we propose solution-processed p-type CuI TFTs which were subject to the thermal annealing process in air and vacuum atmospheres at temperatures of 100, 200, and 300 °C. The chemical states and surface morphologies of the CuI thin films were systematically investigated, revealing the generation of iodine vacancy states and the reduction of carrier concentration, as well as increased film density and grain size according to the annealing condition. Further, the effective role of the Al2O3 passivation layer on the electrical characteristics of the solution-processed CuI TFTs is demonstrated for the first time, where the Al2O3 precursor greatly enhanced the electrical performance of the CuI TFTs, exhibiting a field-effect mobility of 4.02 cm2/V·s, a subthreshold swing of 0.61 V/decade, and an on/off current ratio of 1.12 × 104, which exceed the values of CuI TFTs reported so far. Based on the synergistic effects of the annealing process and the passivation layer that engineered the iodine vacancy state and morphology of CuI, the proposed CuI TFTs with the Al2O3 passivation layer showed excellent reliability under 100 times repeated operation and long-term stability over 216 h, where the transfer curves slightly shifted in the positive direction of 1.36 and 1.88 V measured at a current level of 10–6 A for the reliability and stability tests, respectively. Thus, this work opens a new window for solution-processed p-type CuI TFTs with excellent stability for developing next-generation complementary logic circuits.

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“…The electrical conductivity obtained ranges from 2 to 6 S cm −1 . These values are about 4 times lower than in the literature [40,46]. The slightly lower values may be due to the manufacturing process and layer thickness determination.…”

Section: Thermoelectric Investigationscontrasting

confidence: 58%

“…The summarized measured and calculated values of open-circuit voltage, short-circuit current, maximal power output, Seebeck coefficient, electric conductivity and power factor for different temperatures (see Figure 4). Optimization of the electrical and thermoelectric properties can be achieved by layer optimization with respect to processes and thickness parameters or, as described in [46], by a subsequent annealing process. In [46] is presented how an additional annealing process affects the electrical and structural properties of CuI and how the thermoelectric properties can be improved by changing the native defect structure in the lattice.…”

Section: Thermoelectric Investigationsmentioning

confidence: 99%

Copper Iodide on Spacer Fabrics as Textile Thermoelectric Device for Energy Generation

et al. 2022

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The integration of electronic functionalities into textiles for use as wearable sensors, energy harvesters, or coolers has become increasingly important in recent years. A special focus is on efficient thermoelectric materials. Copper iodide as a p-type thermoelectrically active, nontoxic material is attractive for energy harvesting and energy generation because of its transparency and possible high-power factor. The deposition of CuI on polyester spacer fabrics by wet chemical processes represents a great potential for use in textile industry for example as flexible thermoelectric energy generators in the leisure or industrial sector as well as in medical technologies. The deposited material on polyester yarn is investigated by electron microscopy, x-ray diffraction and by thermoelectric measurements. The Seebeck coefficient was observed between 112 and 153 µV/K in a temperature range between 30 °C and 90 °C. It is demonstrated that the maximum output power reached 99 nW at temperature difference of 65.5 K with respect to room temperature for a single textile element. However, several elements can be connected in series and the output power can be linear upscaled. Thus, CuI coated on 3D spacer fabrics can be attractive to fabricate thermoelectric devices especially in the lower temperature range for textile medical or leisure applications.

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Effect of native defects on thermoelectric properties of copper iodide films

Cited by 31 publications

References 42 publications

CuI: A Promising Halide for Thermoelectric Applications below 373 K

CuI: A Promising Halide for Thermoelectric Applications below 373 K

Synthesis of Vacancy-Controlled Copper Iodide Semiconductor for High-Performance p-Type Thin-Film Transistors

Copper Iodide on Spacer Fabrics as Textile Thermoelectric Device for Energy Generation

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