Flexible thermoelectric (TE) devices hold great promise for energy harvesting and cooling applications, with increasing significance to serve as perpetual power sources for flexible electronics and wearable devices. Despite unique and superior TE properties widely reported in nanocrystals, transforming these nanocrystals into flexible and functional forms remains a major challenge. Herein, demonstrated is a transformative 3D conformal aerosol jet printing and rapid photonic sintering process to print and sinter solution-processed Bi 2 Te 2.7 Se 0.3 nanoplate inks onto virtually any flexible substrates. Within seconds of photonic sintering, the electrical conductivity of the printed film is dramatically improved from nonconductive to 2.7 × 10 4 S m −1 . The films demonstrate a room temperature power factor of 730 µW m −1 K −2 , which is among the highest values reported in flexible TE films. Additionally, the film shows negligible performance changes after 500 bending cycles. The highly scalable and low-cost fabrication process paves the way for large-scale manufacturing of flexible devices using a variety of high-performing nanoparticle inks.

Layered double hydroxides (LDH) have been extensively investigated for charge storage, however, their development is hampered by the sluggish reaction dynamics. Herein, triggered by mismatching integration of Mn sites, we configured wrinkled Mn/NiCo-LDH with strains and defects, where promoted mass & charge transport behaviors were realized. The well-tailored Mn/NiCo-LDH displays a capacity up to 518 C g−1 (1 A g−1), a remarkable rate performance (78%@100 A g−1) and a long cycle life (without capacity decay after 10,000 cycles). We clarified that the moderate electron transfer between the released Mn species and Co2+ serves as the pre-step, while the compressive strain induces structural deformation with promoted reaction dynamics. Theoretical and operando investigations further demonstrate that the Mn sites boost ion adsorption/transport and electron transfer, and the Mn-induced effect remains active after multiple charge/discharge processes. This contribution provides some insights for controllable structure design and modulation toward high-efficient energy storage.

graphene, [10] conductive polymer, and hybrids, [11] have the ability to interconvert thermal to electrical energy without moving parts. These f-TEGs can be integrated with portable/wearable electronics and sensors, and enable selfpowered devices. In this context, V 2 -VI 3 metal chalcogenides (Bi 2 Te 3 , Sb 2 Te 3 , and related alloys and compounds) [1,[12][13][14][15][16][17] have attracted particular attention because of their high figure of merit (ZT) near room temperature. [18] For example, p-type Bi 2 Te 3 -Sb 2 Te 3 alloys show high performance near room temperature and benefit considerably from nanostructuring. [19] Similar to Bi 2 Te 3 , Sb 2 Te 3 is also a topological insulator, [20] which leads to a complex, nonparabolic band structure, often highly favorable for thermoelectric (TE) performance. [21] It has an extremely high dielectric constant of ε 0 ≈ 100, favorable for high mobility even with large concentration of defects. [22][23][24] Thus Sb 2 Te 3 is potentially an important TE material, the key challenge being to find methods to control its carrier concentration and to effectively nanostructure the material while maintaining this control. So far, most of the reported Sb 2 Te 3 related materials are p-type semiconductors. This is caused by intrinsic defects including Sb vacancies and antisite defects of Sb atoms on the Te sites (Sb Te ) [25] that occur during normal synthesis procedures. Typically, Sb 2 Te 3 bulk single crystals stand out for their unique advantages including a high electrical conductivity (σ) around 3-5 × 10 5 S m −1 , and a reasonable thermal conductivity (κ) around 1-6 W m −1 K −1 . However, Sb 2 Te 3 also has a less competitive Seebeck coefficient (S) around 83-105 µV K −1 . This is due to its high degenerate hole concentration (n > 10 20 cm −3 ) created by the acceptor states mentioned above, [26] especially Sb Te . Thus key problem is to find ways to control the doping level and thereby reduce the hole concentration and to determine the extent to which this can lead to enhanced S and TE performance. Nanostructuring has been employed to enhance S, and to reduce κ as a result of the increased phonon scattering effect. [19,[27][28][29][30] For example, Sb 2 Te 3 with 2D nanoplates morphology presents a 30% increase in S (S = 125 µV K −1 ) near room temperature. [31] S and ZT enhancement in nanostructured Solution-processable semiconducting 2D nanoplates and 1D nanorods are attractive building blocks for diverse technologies, including thermoelectrics, optoelectronics, and electronics. However, transforming colloidal nanoparticles into high-performance and flexible devices remains a challenge. For example, flexible films prepared by solution-processed semiconducting nanocrystals are typically plagued by poor thermoelectric and electrical transport properties. Here, a highly scalable 3D conformal additive printing approach to directly convert solution-processed 2D nanoplates and 1D nanorods into high-performing flexible devices is reported. The flexible films printed using Sb ...

Printing techniques using nanomaterials have emerged as a versatile tool for fast prototyping and potentially large‐scale manufacturing of functional devices. Surfactants play a significant role in many printing processes due to their ability to reduce interfacial tension between ink solvents and nanoparticles and thus improve ink colloidal stability. Here, a colloidal graphene quantum dot (GQD)‐based nanosurfactant is reported to stabilize various types of 2D materials in aqueous inks. In particular, a graphene ink with superior colloidal stability is demonstrated by GQD nanosurfactants via the π–π stacking interaction, leading to the printing of multiple high‐resolution patterns on various substrates using a single printing pass. It is found that nanosurfactants can significantly improve the mechanical stability of the printed graphene films compared with those of conventional molecular surfactant, as evidenced by 100 taping, 100 scratching, and 1000 bending cycles. Additionally, the printed composite film exhibits improved photoconductance using UV light with 400 nm wavelength, arising from excitation across the nanosurfactant bandgap. Taking advantage of the 3D conformal aerosol jet printing technique, a series of UV sensors of heterogeneous structures are directly printed on 2D flat and 3D spherical substrates, demonstrating the potential of manufacturing geometrically versatile devices based on nanosurfactant inks.

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