High Thermoelectric Power Factor Organic Thin Films through Combination of Nanotube Multilayer Assembly and Electrochemical Polymerization

Highly Electrical Conductive PEDOT:PSS/SWCNT Flexible Thermoelectric Films Fabricated by a High-Velocity Non-solvent Turbulent Secondary Doping Approach

Materials based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) can be potentially employed as flexible thermoelectric generators (TEGs) to capture waste heat and generate electrical energy. Among various methods, secondary doping is an effective way to modulate its thermoelectric (TE) performance. Different from conventional measures such as dropping, soaking, and steam fumigation, strong shear is integrated with the doping process and termed high-velocity non-solvent turbulent secondary doping (HNTD). We systematically investigate the transformation of PEDOT:PSS during this procedure and the formation mechanism of its highly conductive pathway. It is illustrated that PEDOT:PSS experiences PSS swelling, the phase separation of PEDOT from PSS, the removal of isolated PSS, and the evolution of PEDOT to a linear conformation. These evolutions contribute to the substantial elevation of electrical conductivity (σ). Furthermore, by employing continuous single-walled carbon nanotube (SWCNT) networks as structural units, highly conductive flexible PEDOT:PSS/SWCNT TE thin films could be prepared without sacrificing the Seebeck coefficient (S). Additionally, the effect of HNTD and direct addition method on TE properties of composite films is also compared. Finally, the PEDOT:PSS composite film with 40 wt % SWCNTs by the HNTD method exhibits the maximized power factor (PF) of 501.31 ± 19.23 μW m^-1 K^-2 with σ of 4717.8 ± 41.51 S cm^-1 and S of 32.6 ± 0.13 μV K^-1 at room temperature. It is worth mentioning that the σ value 4717.8 ± 41.51 S cm^-1 is the highest among the composites based on commercial carbon fillers and organic semiconductors. Finally, a 6-leg TEGs prototype is assembled and illustrates an output power of 4.416 μW under a temperature difference (ΔT) of 58 K. It is thought that such a strategy may provide some guidelines for manufacturing PEDOT:PSS-based functional materials.

Advancement of Polyaniline/Carbon Nanotubes Based Thermoelectric Composites

Organic thermoelectric (TE) materials have been widely investigated due to their good stability, easy synthesis, and high electrical conductivity. Among them, polyaniline/carbon nanotubes (PANI/CNTs) composites have attracted significant attention for pursuing enhanced TE properties to meet the demands of commercial applications. In this review, we summarize recent advances in versatile PANI/CNTs composites in terms of the dispersion methods of CNTs (such as the addition of surfactants, mechanical grinding, and CNT functional group modification methods), fabrication engineering (physical blending and in-situ polymerization), post-treatments (solvent treatments to regulate the doping level and microstructure of PANI), and multi-components composites (incorporation of other components to enhance energy filtering effect and Seebeck coefficient), respectively. Various approaches are comprehensively discussed to illustrate the microstructure modulation and conduction mechanism within PANI/CNTs composites. Furthermore, we briefly give an outlook on the challenges of the PANI/CNTs composites for achieving high performance and hope to pave a way for future development of high-performance PANI/CNTs composites for sustainable energy utilization.

Soft Organic Thermoelectric Materials: Principles, Current State of the Art and Applications

The enormous demand for waste heat utilization and burgeoning eco-friendly wearable materials has triggered huge interest in the development of thermoelectric materials that can harvest low-cost energy resources by converting waste heat to electricity efficiently. In particular, due to their high flexibility, nontoxicity, cost-effectivity, and promising applicability in various fields, organic thermoelectric materials are drawing more attention compared with their toxic, expensive, heavy, and brittle inorganic counterparts. Organic thermoelectric materials are approaching the figure of merit of the inorganic ones via the construction and optimization of unique transport pathways and device geometries. This review presents the recent development of the interdependence and decoupling principles of the thermoelectric efficiency parameters as well as the new achievements of high performance organic thermoelectric materials. Moreover, this review also discusses the advances in the thermoelectric devices with emphasis on their energy-related applications. It is believed that organic thermoelectric materials are emerging as green energy alternatives rivaling their conventional inorganic counterparts in the efficient and pure electricity harvesting from waste heat and solar thermal energy.

"Toolbox" for the Processing of Functional Polymer Composites

The processing methods of functional polymer composites (FPCs) are systematically summarized in “Toolbox”. The relationship of processing method-structure-property is discussed and the selection and combination of tools in processing among different FPCs are analyzed. A promising prospect is provided regarding the design principle for high performance FPCs for further investigation.

ABSTRACT

Functional polymer composites (FPCs) have attracted increasing attention in recent decades due to their great potential in delivering a wide range of functionalities. These functionalities are largely determined by functional fillers and their network morphology in polymer matrix. In recent years, a large number of studies on morphology control and interfacial modification have been reported, where numerous preparation methods and exciting performance of FPCs have been reported. Despite the fact that these FPCs have many similarities because they are all consisting of functional inorganic fillers and polymer matrices, review on the overall progress of FPCs is still missing, and especially the overall processing strategy for these composites is urgently needed. Herein, a “Toolbox” for the processing of FPCs is proposed to summarize and analyze the overall processing strategies and corresponding morphology evolution for FPCs. From this perspective, the morphological control methods already utilized for various FPCs are systematically reviewed, so that guidelines or even predictions on the processing strategies of various FPCs as well as multi-functional polymer composites could be given. This review should be able to provide interesting insights for the field of FPCs and boost future intelligent design of various FPCs. [Image: see text]

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40820-021-00774-5.

Enhancing Thermoelectric Performance of Polyaniline/Single-Walled Carbon Nanotube Composites via Dimethyl Sulfoxide-Mediated Electropolymerization

The fabrication of flexible high-performance organic/inorganic thermoelectric (TE) composite films has been a hot spot for researchers in recent years. In this work, dynamic 3-phase interfacial electropolymerization of aniline, together with physical mixing with single-walled carbon nanotubes (SWCNTs), was adopted to prepare polyaniline/SWCNT (PANI/SWCNT) TE composites. The dimethyl sulfoxide (DMSO) added into the electrochemical polymerization system affords strong capability in improving the TE performance of composite films. Moreover, varying loadings of SWCNTs can also conveniently tune the TE performance of composites. Hence, the resultant composites afford the highest power factor (PF) of 236.4 ± 5.9 μW m^-1 K^-2 at room temperature. This work demonstrates that the introduction of DMSO into the electrolyte and the electrochemical polymerization are highly effective in fabricating high-performance PANI/SWCNT TE composites.

Electrochemical Synthesis of an Organic Thermoelectric Power Generator

Energy harvesting through residual heat is considered one of the most promising ways to power wearable devices. In this work, thermoelectric textiles were prepared by coating the fabrics, first with multiple-wall carbon nanotubes (MWCNTs) by using the layer-by-layer technique and second with poly(3,4-ethylenedioxythiophene) (PEDOT) deposited by electrochemical polymerization. Sodium deoxycholate and poly(diallyldimethylammonium chloride) were used as stabilizers to prepare the aqueous dispersions of MWCNTs. The electrochemical deposition of PEDOT on the MWCNT-coated fabric was carried out in a three-electrode electrochemical cell. The polymerization of PEDOT on the fabric increased the electrical conductivity by ten orders of magnitude (through the plane), establishing an excellent path for electric transport across the fabrics. In addition, the fibers showed a Seebeck coefficient of 14.3 μV K^-1, which is characteristic of highly doped PEDOT. As a proof of concept, several thermoelectric modules were made with different elements based on the coated acrylic and cotton fabrics. The best generator made of 30 thermoelectric elements using acrylic fabrics exhibited an output power of 0.9 μW with a temperature difference of 31 K.

Lightweight and Bulk Organic Thermoelectric Generators Employing Novel P-Type Few-Layered Graphene Nanoflakes

Graphene exhibits both high electrical conductivity and large elastic modulus, which makes it an ideal material candidate for many electronic devices. At present not much work has been conducted on using graphene to construct thermoelectric devices, particularly due to its high thermal conductivity and lack of bulk fabrication. Films of graphene-based materials, however, and their nanocomposites have been shown to be promising candidates for thermoelectric energy generation. Exploring methods to enhance the thermoelectric performance of graphene and produce bulk samples can significantly widen its application in thermoelectrics. Realization of bulk organic materials in the thermoelectric community is highly desired to develop cheap, Earth-abundant, light, and nontoxic thermoelectric generators. In this context, this work reports a new approach using pressed pellets bars of few-layered graphene (FLG) nanoflakes employed in thermoelectric generators (TEGs). First, FLG nanoflakes were produced by a novel dry physical grinding technique followed by graphene nanoflake liberation using plasma treatment. The resultant material is highly pure with very low defects, possessing 3 to 5-layer stacks as proved by Raman spectroscopy, X-ray diffraction measurement, and scanning electron microscopy. The thermal and electronic properties confirm the anisotropy of the material and hence the varied performance characteristics parallel to and perpendicular to the pressing direction of the pellets. The full thermoelectric properties were characterized both parallel and perpendicular to the pressing direction, and the proof-of-concept thermoelectric generators were fabricated with variable amounts of legs.

A New Design of a Thin-Film Thermoelectric Device Based on Multilayer-Structure Module

In this work, a novel multilayer structure thin-film thermoelectric device is proposed for preparing a high performance generator. The result shows that the output voltage of the three-layer thin-film device has a linear increasing trend with the increasing temperature difference. Additionally, the device was also tested as a laser power measurement and displays that it has good sensitivity. Moreover, we also fabricated the multilayer device based on the present three-layer structure. It improves upon the similar output prosperities, confirming that the present multilayer structure thin-film thermoelectric device can be considered for preparing high performance micro-self-powered sources and sensors.

Micro and Macro-Tribology Behavior of a Hierarchical Architecture of a Multilayer TaN/Ta Hard Coating

The micro- and macro-tribological behaviors of a novel hierarchical TaN/Ta coating deposited on Ti6Al4V biomedical alloy by direct current magnetron sputtering were analyzed in the present work. This analysis was associated with the morphological, structural, and mechanical properties, as well as the roughness changes during and after the tribological tests. The wear track of the coating after the macro-tribology tests was evaluated by Raman spectroscopy in order to detect the compounds formed as a result of the tribo-reactions that occurred during the tests. Micro- and macro-tribology behaviors showed a significant wear rate reduction of the hierarchical coating in comparison to the Ti6Al4V substrate. For the case of the micro-tribology tests, this reduction was attributed to the high hardness of the coating (31.4 GPa); however, this hardness caused a considerable increment in the friction coefficient. On the other hand, the macro-tribology performance was associated with the hardness and the ability of the hierarchical architecture to prevent the propagation of cracks. Moreover, the friction coefficient increased considerably at the end of the test; this increment was associated with the tantalum oxides in the wear track detected by Raman spectroscopy.

Poly(3,4-ethylenedioxythiophene)/Te/Single-Walled Carbon Nanotube Composites with High Thermoelectric Performance Promoted by Electropolymerization

Electrochemical polymerization has proven very effective in fabricating flexible organic/inorganic composite films with high thermoelectric (TE) performance. In this work, dynamic three-phase interfacial electropolymerization of 3,4-ethylenedioxythiophene (EDOT) combined with physical mixing of single-walled carbon nanotubes (SWCNT) and tellurium nanowires was employed to prepare PEDOT/Te/SWCNT thermoelectric composites. When the loadings of Te and SWCNT were changed, the electropolymerized PEDOT exhibited great capability of improving TE properties of the resultant composites with a highest electrical conductivity (σ) of 900.3 ± 20.5 S cm^-1 and Seebeck coefficient (S) of 43.4 ± 0.6 μV K^-1, affording maximum power factor (PF) of 169.8 ± 7.8 μW m^-1 K^-2 at room temperature.

Poly(3,4-Ethylenedioxythiophene) Nanoparticles as Building Blocks for Hybrid Thermoelectric Flexible Films

Hybrid thermoelectric flexible films based on poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles and carbon nanotubes were prepared by using layer-by-layer (LbL) assembly. The employed PEDOT nanoparticles were synthesized by oxidative miniemulsion polymerization by using iron(III) p-toluenesulfonate hexahydrate (FeTos) as an oxidant and poly(diallyldimethylammonium chloride) (PDADMAC) as stabilizer. Sodium deoxycholate (DOC) was used as a stabilizer to prepare the aqueous dispersions of the carbon nanotubes. Hybrid thermoelectric films were finally prepared with different monomer/oxidant molar ratios and different types of carbon nanotubes, aiming to maximize the power factor (PF). The use of single-wall (SWCNT), double-wall (DWCNT), and multiwall (MWCNT) carbon nanotubes was compared. The Seebeck coefficient was measured by applying a temperature difference between the ends of the film and the electrical conductivity was measured by the Van der Pauw method. The best hybrid film in this study exhibited a PF of 72 µW m−1K−2. These films are prepared from aqueous dispersions with relatively low-cost materials and, due to lightweight and flexible properties, they are potentially good candidates to recover waste heat in wearable electronic applications.

Realizing High Thermoelectric Performance at Ambient Temperature by Ternary Alloying in Polycrystalline Si1-x-yGexSny Thin Films with Boron Ion Implantation

The interest in thermoelectrics (TE) for an electrical output power by converting any kind of heat has flourished in recent years, but questions about the efficiency at the ambient temperature and safety remain unanswered. With the possibility of integration in the technology of semiconductors based on silicon, highly harvested power density, abundant on earth, nontoxicity, and cost-efficiency, Si_1-x-yGe_xSn_y ternary alloy film has been investigated to highlight its efficiency through ion implantation and high-temperature rapid thermal annealing (RTA) process. Significant improvement of the ambient-temperature TE performance has been achieved in a boron-implanted Si_0.864Ge_0.108Sn_0.028 thin film after a short time RTA process at 1100 °C for 15 seconds, the power factor achieves to 11.3 μWcm^-1 K^-2 at room temperature. The introduction of Sn into Si_1-xGe_x dose not only significantly improve the conductivity of Si_1-xGe_x thermoelectric materials but also achieves a relatively high Seebeck coefficient at room temperature. This work manifests emerging opportunities for modulation Si integration thermoelectrics as wearable devices charger by body temperature.

Unusual Photoelectrochemical Properties of Electropolymerized Films of a Triphenylamine-Containing Organic Small Molecule

The electropolymerized films of poly(L)_n on an indium-tin oxide (ITO) electrode was prepared by anodic electrooxidation of a dichloromethane solution of a triphenylamine-carrying organic molecule L and were characterized/studied by ultraviolet-visible absorption spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, electrochemical impedance spectroscopy, cyclic voltammetry, and photoelectrochemical measurements. Poly(L)_n films were found to show surface-controlled TPA^•+1/0 associated quasi-reversible redox and exceptionally high photocurrent generation properties. At a zero external bias potential and under 100 mW/cm² white light irradiation, a photoelectrochemical device composed of a poly(L)₁-modified ITO as the working electode, a platinum disk counter electrode, and saturated calomel electrode reference electrode in a 0.1 M Na₂SO₄ aqueous solution exhibited a significant cathode photocurrent density of 2.2 μA/cm², which could be switched to be anodic and outperform most previously reported molecule-based modified ITO electrodes under similar experimental conditions. The results indicate that poly(L)_n films offer a number of future perspectives ranging from organic photovoltaic to photoelectrochemical catalysis and sensing.

Enzymatic Modification of Polyamide for Improving the Conductivity of Water-Based Multilayer Nanocoatings

Enzymatic modification, using a protease from Bacillus licheniformis (Subtilisin A), was carried out on polyamide 6.6 (PA6.6) fabric to make it more amenable to water-based nanocoatings used to impart electrical conductivity. The modified PA6.6 fibers exhibit a smoother surface, increased hydrophilicity due to more carboxyl and amino groups, and larger ζ-potential relative to unmodified polyamide. With its improved hydrophilicity and surface functionality, the modified textile is better able to accept a water-based nanocoating, composed of multiwalled carbon nanotubes (MWCNT) stabilized by sodium deoxycholate (DOC) and poly(diallyldimethylammonium chloride) (PDDA), deposited via layer-by-layer assembly. Relative to unmodified fabric, the enzymatically modified fibers exhibit lower sheet resistance as a function of PDDA/MWCNT-DOC bilayers deposited. This relatively green technique could be used to impart a variety of useful functionalities to otherwise difficult-to-treat synthetic fibers like polyamide.

High thermoelectric power-factor composites based on flexible three-dimensional graphene and polyaniline

Hybrid thermoelectric (TE) nanocomposites containing conducting polymers and nanocarbon materials have been extensively studied in recent years due to their unique advantages over single-phase organic/inorganic TE materials. Nanocarbon materials have been developed as conductive nanofillers to improve the electrical conductivity of the polymer matrix, and to create a strong π-π interfacial interaction with the matrix to enhance the TE performance. However, previous designs of the hybrid TE nanocomposites tend to cause aggregation of nanocarbon materials, which is detrimental to the TE performance. Also, they are limited in their fabrication to thin film technologies with submicron thicknesses, which prevents these composites from being used in practical TE devices. Herein, we present the synthesis and thermoelectric properties of free-standing, three-dimensional graphene (3DG)-polyaniline (PANI) composites with greater than 100 μm thicknesses for high performance flexible p-type thermoelectrics. Our 3DG matrix has been synthesized by Chemical Vapor Deposition (CVD) with particulate nickel catalysts, and used as a scaffold for the polymer composites. This material provides an excellent electrical conductivity and a reasonable Seebeck coefficient along with very good mechanical integrity preserved when bending, thus making it a promising candidate for flexible TE. PANI polymer was electrochemically grown on the 3DG scaffold as a filler to further tune the TE properties. The proposed 3DG-PANI composites showed a maximum power factor of 81.9 μW m-1 K-2 with a PANI loading of 80 wt% and highly reproducible TE performance after repeated mechanical bending tests. This novel material provides a different strategy for simple and scalable fabrication of flexible thermoelectrics with high performance TE energy harvesting and improved mechanical properties.

Key parameters for enhancing the thermoelectric power factor of PEDOT:PSS/PANI-CSA multilayer thin films

Among the conducting polymers, poly(3,4-ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been extensively investigated for organic thermoelectric device applications owing to its high electrical conductivity (σ), flexibility and easy processability. The thermoelectric (TE) power factor – a factor that determines the efficiency of a thermoelectric material, is very critical in developing high-efficiency thermoelectric devices. The TE power factor of PEDOT:PSS requires further enhancement in realizing efficient organic TE devices. Recently, we have reported a layer-by-layer deposition technique to deposit PEDOT:PSS and poly aniline-camphor sulfonic acid (PANI-CSA) forming a PEDOT:PSS/PANI-CSA multilayer (ML) thin film structure with an enhanced thermoelectric power factor up to 49 μW m⁻¹ K⁻¹. However, there exist several ambiguities regarding the parameters that control the TE power factor in (ML) thin films. In order to identify the parameters that control the TE power factor of ML thin films, PEDOT:PSS/PANI-CSA ML thin films have been deposited by varying the deposition conditions such as spin speed, the number of layers, solvent treatment, and thickness of each layer. A thermoelectric power factor up to 325 μW m⁻¹ K⁻¹ is achieved by properly optimizing the spin speed, number of layers, and the thickness of each layer in ML thin films. The enhanced thermoelectric power factor is the result of multiple factors such as stretching of PEDOT chains, structural conformation change from benzoid to quinoid, and excess PSS removal from the top of the PEDOT:PSS layer through solvent treatment and at the PEDOT:PSS/PANI-CSA interface. Our study provides the basis for realizing an enhanced thermoelectric power factor of organic thermoelectric multilayer structures consisting of ultra-thin polymer thin films similar to inorganic superlattices having 2D confinement.

The key factors that control the thermoelectric (TE) properties of PEDOT:PSS/PANI-CSA multilayer thin films to enhance the TE power factor.

Recent Progress in Flexible Organic Thermoelectrics

Environmental energy issues caused by the burning of fossil fuel such as coal, and petroleum, and the limited resources along with the increasing world population pose a world-wide challenge. Alternative energy sources including solar energy, wind energy, and biomass energy, have been suggested as practical and affordable solutions to future energy needs. Among energy conversion technologies, thermoelectric (TE) materials are considered one of the most potential candidates to play a crucial role in addressing today's global energy issues. TE materials can convert waste heat such as the sun, automotive exhaust, and industrial processes to a useful electrical voltage with no moving parts, no hazardous working chemical-fluids, low maintenance costs, and high reliability. These advantages of TE conversion provide solutions to solve the energy crisis. Here, we provide a comprehensive review of the recent progress on organic TE materials, focused on polymers and their corresponding organic composites incorporated with carbon nanofillers (including graphene and carbon nanotubes). Various strategies to enhance the TE properties, such as electrical conductivity and the Seebeck coefficient, in polymers and polymer composites will be highlighted. Then, a discussion on polymer composite based TE devices is summarized. Finally, brief conclusions and outlooks for future research efforts are presented.

Manipulation of p-/n-Type Thermoelectric Thin Films through a Layer-by-Layer Assembled Carbonaceous Multilayer Structure

Recently, with the miniaturization of electronic devices, problems with regard to the size and capacity of batteries have arisen. Energy harvesting is receiving significant attention to solve these problems. In particular, the thermoelectric generator (TEG) is being studied for its ability to harvest waste heat energy. However, studies on organic TEGs conducted thus far have mostly used conductive polymers, making the application range of TEGs relatively narrow. In this study, we fabricated organic TEGs using carbonaceous nanomaterials (i.e., graphene nanoplatelet (GNP) and single-walled carbon nanotube (SWNT)) with polyelectrolytes (i.e., poly(vinyl alcohol) (PVA) and poly (diallyldimethyl ammonium chloride) (PDDA)) via layer-by-layer (LbL) coating on polymeric substrates. The thermoelectric performance of the carbonaceous multilayer structure was measured, and it was confirmed that the thermoelectric performance of the TEG in this study was not significantly different from that of the existing organic TEG fabricated using the conductive polymers. The 10 bilayer SWNT thin films with polyelectrolyte exhibited a thermopower of -14 μV·K^-1 and a power factor of 25 μW·m^-1K^-2. Moreover, by simply changing the electrolyte, p- or n-type TEGs could be easily fabricated with carbonaceous nanomaterials via the LbL process. Also, by just changing the electrolyte, p- or n-type of TEGs could be easily fabricated with carbonaceous nanomaterials with a layer-by-layer process.

Thermoelectric properties of electrospun carbon nanofibres derived from lignin

Developing sustainable and efficient thermoelectric materials is a challenge because the most common thermoelectric materials are based on rare elements such as bismuth and telluride. In this context, we have produced bio-based carbon nanofibres (CNFs) derived from mixtures of polyacrylonitrile and lignin using electrospinning. The addition of lignin (up to 70%) reduces the diameter of CNFs from 450 nm to 250 nm, increases sample flexibility, and promotes inter-fibre fusion. The crystalline structure of the CNFs was analysed by Raman spectroscopy. The electrical conductivity and the Seebeck coefficient were evaluated as function of the lignin content in the precursor and carbonised equivalents. Finally, a conversion of p-type to n-type semiconducting behaviour was achieved with a hydrazine vapour treatment. We observe a maximum p-type power factor of 9.27 μW cm^-1 K^-2 for CNFs carbonised at 900 °C with 70% lignin which is a 34.5-fold increase to the CNFs with 0% lignin. For the hydrazine treated samples, we observe a maximum n-type power factor of 10.2 μW cm^-1 K^-2 for the CNFs produced in the same way which is an 11.0-fold increase to the hydrazine-treated CNFs with 0% lignin.

In Situ Complementary Doping, Thermoelectric Improvements, and Strain-Induced Structure within Alternating PEDOT:PSS/PANI Layers

Although the deposition of alternating layers from poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and polyaniline (PANI) salts has recently provided a breakthrough in the field of conductive polymers, the cause for the conductivity improvement has remained unclear. In this work, we report a cooperative doping effect between alternating PANI base and PEDOT:PSS layers, resulting in electrical conductivities of 50-100 S cm^-1 and power factors of up to 3.0 ± 0.5 μW m^-1 K^-2, which surpass some of the recent values obtained for protonated PANI/PEDOT:PSS multilayers by a factor of 20. In this case, the simultaneous improvement in the electrical conductivity of both types of layers is caused by the in situ protonation of PANI, which corresponds to the removal of the excess acidic PSS chains from the PEDOT:PSS grains. The interplay between the functional groups' reactivity and the supramolecular chain reorganization leads to an array of preparation-dependent phenomena, including a stepwise increase in the film thickness, an alternation in the electrical conductivity, and the formation of a diverse surface landscape. The latter effect can be traced to a buildup of strain within the layers, which results in either the formation of folds or the shrinkage of the film. These results open new paths for designing nanostructured thin-film thermoelectrics.