Flexible Thermoelectric Generator Research Articles

High‐performance and flexible thermoelectric generator based on a robust carbon nanotube/BiSbTe foam

AbstractOrganic thermoelectric generators (TEGs) are flexible and lightweight, but they often have high electrical resistance, poor output power, and low mechanical durability, because of which their thermoelectric performance is poor. We used a facile and rapid solvent evaporation process to prepare a robust carbon nanotube/Bi0.45Sb1.55Te3 (CNT/BST) foam with a high thermoelectric figure of merit (zT). The BST sub‐micronparticles effectively create an electrically conductive network within the three‐dimensional porous CNT foam to greatly improve the electrical conductivity and the Seebeck coefficient and reinforce the mechanical strength of the composite against applied stresses. The CNT/BST foam had a zT value of 7.8 × 10−3 at 300 K, which was 5.7 times higher than that of pristine CNT foam. We used the CNT/BST foam to fabricate a flexible TEG with an internal resistance of 12.3 Ω and an output power of 15.7 µW at a temperature difference of 21.8 K. The flexible TEG showed excellent stability and durability even after 10,000 bending cycles. Finally, we demonstrate the shapeability of the CNT/BST foam by fabricating a concave TEG with conformal contact on the surface of a cylindrical glass tube, which suggests its practical applicability as a thermal sensor.

Compact Vital-Sensing Band with Uninterrupted Power Supply for Core Body Temperature and Pulse Rate Monitoring.

Although wearable devices for continuous monitoring of vital signs have undergone significant advancements, their need for frequent recharging precludes continuous operation, potentially leading to adverse outcomes being overlooked. Additionally, the scattered locations of the sensors hamper wearability. Herein, we present a compact vital-sensing band with uninterrupted power supply designed for continuous monitoring of core body temperature (CBT) and pulse rate. The band─which comprises two sensors, a power source (i.e., a flexible thermoelectric generator (TEG) and a battery), and a flexible circuit─is worn on the forearm. The CBT is calculated by measuring the skin temperature and heat flux, while a triboelectric nanogenerator-based self-powered pressure sensor is utilized for pulse rate monitoring. The TEG is a flexible unit that converts body heat into electricity, accumulating a total energy of 314 mJ (100%). Out of this total energy, only 43.2 mJ (7.2%) is utilized for CBT measurements, while the remaining 270.80 mJ (92.8%) is stored in the battery. This enables reliable and continuous operation of the vital-sensing band, highlighting its potential for use in healthcare applications.

N-Type Nanocomposite Films Combining SWCNTs, Bi2Te3 Nanoplates, and Cationic Surfactant for Pn-Junction Thermoelectric Generators with Self-Generated Temperature Gradient Under Uniform Sunlight Irradiation.

Flexible thermoelectric generators (TEGs) with pn-junction single-walled carbon nanotube (SWCNT) films on a polyimide substrate have attracted considerable attention for energy harvesting. This is because they generate electricity through the photo-thermoelectric effect by self-generated temperature gradient under uniform sunlight irradiation. To increase the performance and durability of the pn-junction TEGs, n-type films need to be improved as a priority. In this study, bismuth telluride (Bi2Te3) nanoplates synthesized by the solvothermal method were added to the n-type SWCNT films, including a cationic surfactant to form the nanocomposite films because Bi2Te3 has high n-type thermoelectric properties and high durability. The performances of the pn-junction TEGs were investigated by varying the heat treatment times. When the artificial sunlight was uniformly irradiated to the pn-junction TEGs, a stable output voltage of 0.47 mV was observed in the TEG with nanocomposite films heat-treated at 1 h. The output voltage decreased with increasing heat treatment time due to the decrease in the p-type region. The output voltage of TEG at 1 h is higher than that of the TEGs without Bi2Te3 nanoplates under the same conditions. Therefore, the addition of Bi2Te3 nanoplates was found to improve the performance of the pn-junction TEGs. These findings may aid in the development of facile and flexible optical devices, including photodetectors and hybrid devices integrating solar cells.

High-performance waterproof flexible thermoelectric generators for self-powered electronics

Flexible and wearable thermoelectric generators (TEG) have emerged as promising energy sources for wearable health-monitoring devices. However, common thermoelectric generators are difficult to be applied to a wide range of application scenarios due to their poor durability, low output power, and susceptibility to human sweat or underwater environments. Here, we propose a waterproof wearable TEG with a gap structure. Through structural optimization and full-coverage elastomer encapsulation, the wearable TEG has a maximum power density of 4.38 mW∙cm−2 at a temperature difference (ΔT) of 30 K and exhibits good stability under aqueous environments, which is capable of supplying power to electronic devices even under submerged conditions. The internal resistance of wearable TEG changes by less than 10 % at 50 % stretch or 900 degrees of torsion, showing good flexibility and mechanical stability. Based on this, we designed an energy harvesting and management system to help wearable TEG collect and utilize energy on demand, and successfully implemented wireless transmission of human skin temperature data for underwater environments and real-time electrocardiograms (ECG) tests for health detection in air environments. This research provides a reliable method for powering wearable electronic devices using thermoelectric generators.

Achieving High Thermoelectric Performance in Bi2(Te, Se)3 Thin Film with (00l)-Oriented by Incorporating Tellurization and Selenization Processes.

Flexible thermoelectric (TE) generators have received great attention as a sustainable and reliable option to convert heat from the human body and other ambient sources into electricity. This study provides a synthesis route that involves thermally induced diffusion to introduce Te and Se into Bi, fabricating an n-type Bi-Te-Se flexible thin film on a flexible substrate. This specific synthesis alters the crystal orientation (00l) of the thin film, improving in-plane electrical transportation and optimizing carrier concentration. Consequently, BixTeySe0.42 enhanced both the Seebeck coefficient and electrical conductivity, achieving a power factor of 17.1 μW cm-1 K-2 at room temperature. The TE device assembled with p-type Sb2Te3 exhibited exceptional flexibility with only a 26.2% change in resistance after 1000 times of bending at a radius of about 6 mm. The resistance change was further reduced to 7.5% after the application of a vinyl laurate coating. The fabricated TE device generated an ultrahigh output power of 792 nW with a temperature difference of 30 K.

Flexible polyester-embedded thermoelectric device with Bi2Te3 and Te legs for wearable power generation

This study presents an approach for powering wearable sensors by integrating nanostructured bismuth telluride (Bi2Te3 and Te legs) into flexible polyester substrates. The choice of polyester as the substrate is because it is widely used in clothing, especially in items such as shirts, blouses, dresses, and sportswear. This enables seamless integration with wearable devices. By capturing wasted body heat, our small and flexible thermoelectric generators (TEGs) offer long-term operation without the need to plug the batteries. We demonstrate the feasibility of using commercially available polyester for reproducible electrochemical deposition of highly oriented Bi2Te3 and Te material. Through electrodeposition, we embed Bi2Te3 and Te legs within the flexible polyester, creating a cost-effective and easily scalable hybrid system for wearable energy harvesting.Our optimized TEG design, which can be worn on the arm or forehead, achieves impressive power density compared to existing state-of-the-art solutions. With a mere 3.5 °C temperature difference, only two pairs of p- and n-type legs, and a thickness of approximately 15 µm, our TEG generates a maximum open circuit voltage of ∼0.1 mV and a maximum power density of ∼0.04 mW·K-1·cm−2. With 250 pairs, 10 mV can be reached. This cost-effective design also integrates electrical contacts, surpassing previous flexible TEG performances. These advancements make our TEGs suitable for driving microwatt-level electronic sensors and open new avenues for efficient energy harvesting in wearable applications.

Optimization of material properties and performance of flexible thermoelectric generators with/without graphene

With the advancement of energy harvesting methods, the power level consumed by electronic circuits and sensors has been reduced so that self-sufficiency in power can be achieved, and the use of flexible thermoelectric generators to supply electrical energy is one of these methods. In this study, the manufacture of flexible thermoelectric generators is successfully developed and verified using a numerical method. The process follows the sandwich method of the conventional thermoelectric module and utilizes two different elastomers (polydimethylsiloxane and Eco-Flex) and thin copper sheets. Among the nine cases designed by the Taguchi method, the maximum tensile strength of the elastomer is 0.967 MPa, stemming from the operation conditions of 6 min stirring time, 85 °C heating temperature, and 3 h heating time. This strength is substantially higher than those of the other eight cases. The open-circuit voltage of the manufactured flexible thermoelectric generator with an internal resistance of 1.5 Ω is 0.011 V. The output power under a temperature difference of 75 °C is 11 μW. After blending graphene into polydimethylsiloxane, the elastomer’s thermal conductivity at 370 K rises by 9.6 folds. This results in the output power being lifted to 0.0515 W (75 °C temperature difference), accounting for an amplification of 4,681 times. Numerical simulations are also performed to aid in figuring out the detailed performance of the flexible thermoelectric generator. The errors between numerical simulations and experiments are between 4.6 % and 5.2 %, showing the reliability of the numerical predictions. The fabricated flexible thermoelectric generators can be practically used for green power generation by harvesting industrial low-temperature waste heat and biothermal energy, potentially driving sensors on industrial devices, the human body, and animals.

Patternable and flexible thermoelectric generators based on Bi2Te3/silk fibroin composites for temperature sensing and wearable applications

Thermoelectric (TE) materials are functional materials that can directly convert heat energy into electrical energy, and have a positive effect on alleviating the energy crisis. Inorganic semiconductor materials have attracted extensive attention due to their excellent TE properties, among which Bi2Te3 is the best and most widely used inorganic TE material at room temperature. However, inorganic TE materials are still restricted by unfavorable factors such as scarcity of raw material resources, heavy metal pollution, high price, high rigidity, and complex processing technology, which greatly limit their development process. Therefore, it is urgent to develop flexible TE materials with high performance, non-polluting, non-toxic and low price. The combination of silk fibroin and inorganic TE materials not only retains the properties of TE materials, but also improves their flexibility. Here, the Bi2Te3/SF TE films are successfully fabricated by the evaporation-assisted self-assembly method with Seebeck coefficient of 199 μV⋅K−1 (p-type) and −240 μV⋅K−1 (n-type). In order to verify the feasibility of collecting and utilizing ambient heat energy in real life, the Bi2Te3/SF TE films are cut into various patterns (such as, flower, rabbit, tree, etc) to collect wasted ambient heat. Further, the Bi2Te3/SF thermoelectric generator (TEG) reaches a maximum power of 21 nW at a temperature difference of 43.5 K. A series of self-power temperature sensing demonstrations from single TE film, TEG, to TEG array are proposed to demonstrate their potential applications in the field of self-power sensors. Finally, by inserting Bi2Te3/SF TEG array into a bracelet, a self-powered smart bracelet can be successfully constructed, demonstrating the feasibility of the Bi2Te3/SF TE film in the development of self-powered wearable electronics.

Flexible Porous Ag2Se Films: From Freestanding Inorganic Films to Inorganic‐Network/Organic‐Skeleton Thermoelectric Generators

AbstractSilver selenide (Ag2Se) flexible films are promising near‐room‐temperature thermoelectric candidates for low‐grade heat harvesting. However, existing Ag2Se films are generally attached on substrates, which impedes further flexibility improvement of the films and constrains the scenarios of applications. Here a cost‐effective and scalable strategy is presented, which combines screen printing and annealing, for synthesizing freestanding Ag2Se inorganic films with different densities of pores. High‐density pores and thin thickness endow the films with high flexibility, while films with low‐density pores obtain higher power factor. Furthermore, by utilizing the porous microstructure, a composite structure consisting of a Ag2Se conductive network and an organic polydimethylsiloxane (PDMS) skeleton is fabricated, which further improves films’ stability under bending and torsion. Finally, a flexible thermoelectric generator comprising five Ag2Se/PDMS legs and encapsulated PDMS outputs a voltage of 20.2 mV and a maximum power of 810 nW (the corresponding power density is 5.4 W m−2) at a temperature difference of 30 K, verifying potential application at near room temperature. This work offers a useful paradigm for fabricating substrate‐free Ag2Se porous films with high flexibility for near‐room‐temperature thermoelectric applications.

Electrospun biomass polyethylene furanoate nonwoven substrates for flexible thermoelectric generators

Polyethylene furanoate (PEF) stands out as a highly promising biopolymer, characterized by its lower melting point and higher flexibility than those of polyethylene terephthalate (PET). Moreover, the enhanced functionality of PEF broadens its potential applications across various domains. Herein, the synergistic integration of PEF with a polymer thermoelectric layer is explored via the formulation of advanced environmentally sustainable materials for prospective utilization in flexible thermoelectric generators for the emerging field of green energy. The fabrication process involves the creation of PEF nonwoven via the electrospinning technique, thereby endowing the PEF with considerable stretchability. Concurrently, the polymer thermoelectric layer is developed by blending dimethyl sulfoxide (DMSO) and d-sorbitol in a poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) solution, followed by drop-casting PEDOT:PSS onto glass substrates. Subsequently, free-standing PEDOT:PSS films are transposed onto PEF nonwoven substrates with a power factor of 17.84 μW m⁻1 K⁻2 and an elongation of 24 % at breaking point. The intimate compatibility between the PEDOT:PSS film and PEF nonwoven substrate is demonstrated by the cyclic bending test results, wherein over 90 % of the original conductivity is maintained after 1000 cycles, thereby highlighting the potential of the developed device as a thermoelectric generator. Finally, a 12-leg thermoelectric generator is fabricated, yielding an output voltage of 3.63 mV and an output power of 34.52 nW under a temperature gradient of 32.3 K.

Efficient low-grade heat harvesting with flexible paper-based thermoelectric generators fabricated by facile process

The study presents the fabrication and characterization of paper-based thermoelectric generators (PTGs) using p-type Bi0.5Sb1.5Te3 (BST) and n-type Bi2Te2.7Se0.3 (BTS) thermoelectric (TE) materials, deposited via a novel cotton swab powder deposition technique. This method eliminates the need for complex equipment or high-temperature processes, reducing fabrication complexity and enabling large-scale production. The key advancements of this method are its simplicity, cost-effectiveness, and practical applicability, ensuring uniform coating and good material adherence to the paper substrate. The PTGs, consisting of five p-n pairs interconnected with various materials, were laminated for enhanced stability and humidity protection. Experimental measurements under temperature gradients(ΔTs) of 5–30 °C revealed an optimal configuration achieving an open-circuit voltage(Voc) of 42.60 mV, internal resistance(Rint) of 42.50kΩ, short-circuit current(Isc) of 1.00µA, and maximum power output(Pmax) of 10.65nW for the carbon paste/copper sheet interconnected PTG at ΔT of 30 °C. The obtained normalized power density is 5.68nWcm-2K-1pair-1, which is one of the best among the reported Bi2Te3-based PTGs. A preliminary demonstration on an arm showed the PTG generating an 11.95 mV output voltage in hot weather conditions (ΔT ≈ 8 °C), effectively harnessing body heat for wearable electronics. This work highlights a simple, cost-effective, and scalable method for fabricating PTGs for sustainable energy harvesting in low-power wearable applications. Future efforts will focus on optimizing materials, fabrication techniques, and novel designs to enhance efficiency and scalability.

Impact of Geometrical Factors on the Effectiveness of a Flexible Organic Thermoelectric Generator

Impact of Geometrical Factors on the Effectiveness of a Flexible Organic Thermoelectric Generator

Flexible Screen‐Printed Thermoelectric Materials Based on PEDOT:PSS/DWCNT Composites

AbstractScreen printing technology is employed to prepare poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/double‐walled carbon nanotubes (DWCNT) films as active p‐type material for flexible thermoelectric generators (TEGs). Performance of the PEDOT:PSS/CNT composites have been optimized by changing the formulation inks to make them suitable for screen printing, by varying the CNT concentrations and by treating the printed polymeric films in ethylene glycol (EG). The purpose of this work is finding the processing conditions that optimize conductivity, Seebeck coefficient, and the power factor of the fully printed material. From experimental data, the composite with 10% by weight of DWCNT chemically treated in EG maximizes conductivity, Seebeck coefficient, and power factor of the material.

Automobile exhaust flexible thermoelectric harvester enabled by liquid metal-based heatsink

The softening thermoelectric generator based on a deformable heatsink is expected to facilitate achieving remarkable temperature differences and thermal harvesting capabilities while alleviating exhaust back pressure and engine operating perturbations. However, the available soft polymer materials with poor thermal characteristics face challenges in realizing efficient heat transfer. Herein, we reported a highly integrated automobile exhaust flexible thermoelectric generator (IAE-FTEG) enabled by a liquid metal (LM)-based stretchable heatsink for cylindrical thermal sources to achieve efficiently harnessing waste heat energy and continuously powering multiple vehicle-mounted sensors. IAE-FTEG exhibits excellent flexibility (the bending radius at the apex of 0.57 cm) and outstanding heat transfer capability by introducing the porous sandwich-based soft electrode films and LM-based thermal interface material, achieving an output power enhancement of 25.7 %. The flexible heatsink is prepared by embedding LM droplets and copper particles into the elastic matrix forming solid–liquid multiphase composites, which obtain considerable thermal conductivity (2.40 W/mK@200 % stretching deformation) and excellent geometric conformity. We built the bench and the real vehicle test platform of the IAE-FTEG waste heat recovery system. The simulation test results demonstrate that the maximum power density achieved by the IAE-FTEG waste heat recovery system is 244 kW/m3. The real vehicle tests show that the IAE-FTEG waste heat recovery system has a relatively stable output performance with an average power density of 117 kW/m3 under urban conditions and can realize a stable power supply for back-end loads. Our IAE-FTEG can offer new opportunities in enabling efficient curved-surface waste heat recovery, flexible wearable electronics, and personalized thermal management.

Screen printing Ag2Se/carbon nanocomposite films for flexible thermoelectric applications

Flexible thermoelectric generators offer the possibility of harvesting waste heat from the human body. However, intrinsic brittleness and the high production cost of bulk thermoelectric materials limit their applications in flexible thermoelectric generators. Herein, flexible Ag2Se/carbon nanocomposite films on polyimide substrates are prepared by scalable screen-printing followed by facial heat treatment. An optimal film shows a maximum power factor of 1617 μW m−1 K−2 at room temperature and good flexibility. The film consists of mainly Ag2Se grains with a preferred (00Ɩ)-orientation and a small amount of carbon. Microstructure observations reveal that the Ag2Se grains with sizes of nano to micrometers have coherent or continuous grain boundaries, and the carbon is mainly amorphous with slight graphitization. A flexible thermoelectric device assembled with the optimal film exhibits a power density of 29.1 W/m2 at a temperature gradient of 35.4 K. This work demonstrates a cost-effective route to high-performance flexible thermoelectric films.

Flexible thin-film thermoelectric generators for human skin-heat harvesting: A numerical study

By harvesting thermal energy from human skin, self-powered wearable electronics have the potential to overcome the limitations of battery power, enabling long-term continuous operation. Flexible thermoelectric generators (TEGs) that can form a conformal contact with heat sources of any shape are critical for self-powered wearables. Nevertheless, practical implementations and efficient harvesting of heat energy from the human body are still hindered by factors that significantly diminish the power output of flexible TEGs. In this work, we present a design framework and computational platform optimized for modelling the harvesting of skin-heat energy using organic-based flexible thin-film TEGs. First, a three-dimensional numerical model based on the finite element method (FEM) has been developed, which enables the study and optimization of organic-based film thermoelectric (TE) device and TEG parameters, such as width, length, thickness, and interconnection dimensions, to maximize performance. Then, the optimized flexible TEG has been used to investigate the effect of human skin on wearable device applications in different parts of the body and environmental conditions. Mechanical interlayers designed to control various interface functions can alter junction resistances, leading to structures that are either highly conductive or insulating. Soft heat conductor (SHC) and soft heat insulator (SHI) layers are embedded to enhance the thermal interfaces and temperature difference across the TEG. As a result, embedding these soft heat layers can increase the temperature difference (ΔT) and open circuit voltage (VOC) along the TEG by ∼30 % over conventional flexible thin-film TEGs, while preserving mechanical softness and flexibility. Additionally, a study on the impact of the skin/TEG matching and heat flux at the skin/TEG interface is presented. Lastly, using a state-of-the-art post-treated poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) film-based TEG device model, we determined the maximum power output obtainable on various parts of the human body under three distinct environmental conditions (cold, room, and hot temperatures).

π-Conjugated metallo-copolymer/SWCNT composites for high performance thermoelectric generators

Organic materials have attracted extensive attention in flexible thermoelectric generators due to their solution processability, low thermal conductivity and high flexibility. However, their thermoelectric performances are still far behind those of the inorganic counterparts (e.g. Bi2Te3, PbTe and other related alloys). Here, by virtue of the dual advantages of both inorganic and organic materials, three Pt (II)-containing diketopyrrolopyrrole (DPP) based donor−acceptor (D−A)-type π-conjugated metallo-copolymers (P1Pt, P2Pt and P3Pt) are designed and synthesized, and they are compared with their control copolymers without Pt (II)-coordination (P1, P2 and P3). It is shown that Pt (II) centers and copolymerized molecular structures play important roles in tuning the bandgap and coplanarity. A large Fermi level shift is observed after doping with single-walled carbon nanotubes (SWCNTs) in the copolymers. As expected, the introduction of Pt (II)-side chains and doping of SWCNTs into copolymers could significantly improve the power factor (PF), which reaches the highest value of 276.5 ± 26.6 μW m−1 K−2 for P3Pt/60 wt% SWCNTs. The corresponding p-type thermoelectric generator exhibits a large output power of up to 0.55 μW under a 109 K temperature gradient. Our results can provide a pathway for designing and preparing efficient thermoelectric materials and flexible thermoelectric generators.

Capillary compression induced outstanding n-type thermoelectric power factor in CNT films towards intelligent temperature controller

One-dimensional carbon nanotubes are promising candidates for thermoelectrics because of their excellent electrical and mechanical properties. However, the large n-type power factor remains elusive in macroscopic carbon nanotubes films. Herein, we report an outstanding n-type power factor of 6.75 mW m−1 K−2 for macroscopic carbon nanotubes films with high electrical and thermal conductivity. A high-power density curl-able thermoelectric generator is fabricated with the obtained carbon nanotubes films, which exhibits a high normalized power output density of 2.75 W m−1 at a temperature difference of 85 K. The value is higher than that of previously reported flexible all-inorganic thermoelectric generators (<0.3 W m−1). An intelligent temperature controller with automated temperature-controlling ability is fabricated by assembling these thermoelectric generators, which demonstrates the potential application of the carbon nanotubes films in automated thermal management of electronic devices where requires a large thermoelectric power factor and a large thermal conductivity simultaneously.

Enhanced Thermoelectric Performance in Flexible Sulfur-Alloyed Ag2Se Thin Films.

Flexible thermoelectric generators can directly convert thermal energy harvested from the human body into electricity. The Ag2Se flexible film, a promising material for wearable thermoelectric generators, normally demonstrates an inferior electrical transport property due to its weakened in-plane mobility. In this study, the in-plane electrical transport properties of flexible Ag2Se films were optimized by alloying with additional sulfur. This optimization is achieved by leveraging the differences in elemental electronegativity and the preferred orientation of the Ag2Se films. The sulfur-alloyed Ag2Se thin film, with a nominal ratio of 3 atom %, can reach a maximum mobility of 1150 cm-2 V-1 s-1 at 300 K. So, the optimized room-temperature power factor increases to 1935 μW m-1 K-2. Furthermore, the Ag2Se film alloyed with 3 atom % sulfur exhibits excellent flexibility even after 1000 bending cycles with a radius of 5 mm, characterized by a relative resistance increment of less than 3%. In addition, the corresponding π-type flexible thermoelectric generator possesses a maximum power density of 51 W m-2 at a temperature difference of 50 K.

Greatly Enhanced Thermoelectric Performance of Flexible Cu2-xS Composite Film on Nylon by Se Doping.

In this work, flexible Cu2-xS films on nylon membranes are prepared by combining a simple hydrothermal synthesis and vacuum filtration followed by hot pressing. The films consist of Cu2S and Cu1.96S two phases with grain sizes from nano to submicron. Doping Se on the S site not only increases the Cu1.96S content in the Cu2-xS to increase carrier concentration but also modifies electronic structure, thereby greatly improves the electrical properties of the Cu2-xS. Specifically, an optimal composite film with a nominal composition of Cu2-xS0.98Se0.02 exhibits a high power factor of ~150.1 μW m-1 K-2 at 300 K, which increases by ~138% compared to that of the pristine Cu2-xS film. Meanwhile, the composite film shows outstanding flexibility (~97.2% of the original electrical conductivity is maintained after 1500 bending cycles with a bending radius of 4 mm). A four-leg flexible thermoelectric (TE) generator assembled with the optimal film generates a maximum power of 329.6 nW (corresponding power density of 1.70 W m-2) at a temperature difference of 31.1 K. This work provides a simple route to the preparation of high TE performance Cu2-xS-based films.