Thermal Management Of Electronic Devices Research Articles

Achieving Ultra-High Heat Flux Transfer in Graphene Films via Tunable Gas Escape Channels.

Graphene films have been applied in the thermal management of electronic devices due to their high thermal conductivity. However, the ever-increasing power and local heat flux density of electronic chips require graphene films with excellent heat flux carrying capacity. Enhancing the heat flux carrying capacity is highly challenging, and the key is to maintain high thermal conductivity while increasing film thickness. Gases released during film assembly and the resulting catastrophic structural destruction should be responsible for the trade-off between film thickness and thermal conductivity. Herein, the evolution of the pore structure is investigated during the assembly of graphene films and propose the construction of gas escape channels for the preparation of thick graphene films. The process involves using humidification treatment and freeze-drying GO films to pre-construct the ordered flat pore structure. The microstructure optimization of graphene films with more order, fewer wrinkles and defects, and larger grain size is achieved. After optimization, graphene films with ultra-high thermal conductivity (1781Wm-1K-1) and a thickness over 100µm are realized. These films exhibit exceptional heat dissipation and cooling capabilities in high heat flux density (≈2000Wcm-2). This finding holds significant potential for guiding the thermal management of high-power devices.

Effect of wall contact angle on the conjugate heat transfer for flow boiling processes in rectangular microchannels

Microchannel boiling heat transfer offers a promising solution to address extreme high heat flux in miniaturized and high-density integrated electronic devices. In this work, we performed numerical studies to elucidate the complex flow boiling process in a square microchannel using the open-source platform OpenFOAM. The governing equations of the two-phase flow was solved based on the finite volume framework, and the surface tension together with phase change models were incorporated to study the wettability and conjugate heat transfer in the microchannel. First, the stability of the liquid film shows that smaller contact angles lead to thicker and stable liquid films near the solid wall, while larger contact angles result in thinner and fragile films. Second, the heat transfer, represented by the dimensionless parameter Nu, shows that smaller contact angles result in higher and more uniform distribution of Nu. The velocity gradient causes the Nu to be higher for the sidewalls than for the bottom wall. The contact angle also affects the peak value of Nu. Small contact angles result in large solid wall temperature gradients and more efficient heat transfer. Finally, the simulation results show that smaller thermal conductivity of the solid results in larger temperature gradient in the flow direction, implying that the conjugate heat transfer is less efficient. Overall, the present numerical findings provide useful guidance for efficient thermal management in electronic devices.

Evaluation of Thermal and Mechanical Properties of Bi-In-Sn/WO3 Composites for Efficient Heat Dissipation.

Phase change materials (PCMs) offer promising solutions for efficient thermal management in electronic devices, energy storage systems, and renewable energy applications due to their capacity to store and release significant thermal energy during phase transitions. This study investigates the thermal and physical properties of Bi-In-Sn/WO3 composites, specifically for their use as phase change thermal interface materials (PCM-TIMs). The Bi-In-Sn/WO3 composite was synthesized through mechanochemical grinding, which enabled the uniform dispersion of WO3 particles within the Bi-In-Sn alloy matrix. The addition of WO3 particles markedly improved the composite's thermal conductivity and transformed its physical form into a putty-like consistency, addressing leakage issues typically associated with pure Bi-In-Sn alloys. Microstructural analyses demonstrated the existence of a continuous interface between the liquid metal and WO3 phases, with no gaps, ensuring structural stability. Thermal performance tests demonstrated that the Bi-In-Sn/WO3 composite achieved improved thermal conductivity, and reduced volumetric latent heat, and there was a slight increase in thermal contact resistance with higher WO3 content. These findings highlight the potential of Bi-In-Sn/WO3 composites for utilization as advanced PCM-TIMs, offering enhanced heat dissipation, stability, and physical integrity for high-performance electronic and energy systems.

Vascular bundle-structured polymeric composites with fire-safe, self-detecting and heat warning capabilities for power batteries thermal management

The trend of miniaturization and integration poses challenges to the thermal management of electronic devices, requiring high thermal conductivity and potential fire safety, etc. In this study, inspired by plant vascular structure, we developed a polymer composite with a vertical vascular bundle structure via a sacrificial template method and subsequent assembly of transition metal carbides/nitrides (MXene) nanosheets and phytic acid (PA) coordinated cobalt ions (Co2+) complex. The embedded MXene and PA@Co exhibit multilayer multiscale structural features, forming heat transfer channels and protective cells within the composite. The resultant composites possess high out-of-plane thermal conductivity (∼1.54 W‧m−1‧k−1) and excellent flame retardancy, including self-extinguishing, and significantly reduced heat and smoke release. Interestingly, the MXene vascular bundle structure imparts heat early warning capabilities and intelligent damage self-detection, suggesting an effective means of preventing early-stage fires and real-time monitoring of composite structural and functional integrity. Such biomimetic strategies enable new insights into the designing of multifunctional, intelligent polymer composites.

Assessment of Thermal Management Using a Phase-Change Material Heat Sink under Cyclic Thermal Loads

Phase-change materials (PCMs) are widely used in the thermal management of electronic devices by effectively lowering the hot end temperature and increasing the energy conversion efficiency. In this article, numerical studies were performed to understand how temperature instability during the periodic utilization of electronic devices affects the heat-dissipation effectiveness of a phase-change material heat sink embedded in an electronic device. Firstly, three amplitudes of 10 °C, 15 °C, and 20 °C for fixed periods of time, namely, 10 min, 20 min, and 40 min, respectively, were performed to investigate the specific effect of amplitude on the PCM melting rate. Next, the amplitude was fixed, and the impact of the period on heat sink performance was evaluated. The results indicate that under the 40 min time period, the averaged melting rate of PCMs with amplitudes of 20 °C, 15 °C, and 10 °C reaches the highest at 19 min, which saves 14 min, 10 min, and 8 min, respectively, compared with the constant input of the same melting rate. At a fixed amplitude of 20 °C, the PCM with a period of 40 min, 20 min, and 10 min has the highest averaged melting rate at 6 min, 11 min, and 19 min, saving the heat dissipation time of 3 min, 8 min, and 14 min, respectively. Overall, it was observed that under identical amplitude conditions, the peak melting rate remains consistent, with longer periods resulting in a longer promotion of melting. On the other hand, under similar conditions, larger amplitude values result in faster melting rates. This is attributed to the fact that the period increases the heat flux output by extending the temperature rise, while the amplitude affects the heat flux by adjusting the temperature.

Novel nano-Y2O3/myristic acid nanocomposite PCM for cooling performances of electronic device with various fin designs

Effective thermal management is critical for enhancing the longevity and operational efficiency of electronic devices. This research introduces a novel cooling approach by incorporating Yttrium Oxide (Y2O3) nanoparticles into Phase Change Materials (PCMs) to improve thermal management in electronic devices. This study focuses on developing nanocomposite PCMs with Y2O3 nanoparticles embedded in a myristic acid (MA) matrix through melting and physical mixing. Nanoparticles were added to MA at various mass fractions: 0.5 %, 1 %, 1.5 %, and 2 %. Structural and morphological analyses were conducted using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and field emission scanning electron microscopy combined with energy dispersive X-ray spectroscopy (FE-SEM-EDX). Thermophysical properties were characterized using differential scanning calorimetry (DSC) and thermal conductivity measurements with the KD2-Pro device. The inclusion of Y2O3 nanoparticles significantly enhanced the thermal conductivity of the PCM, reaching up to 0.229 W/m·K in the solid phase and 0.177 W/m·K in the liquid phase, representing improvements of 43.125 % and 18 %, respectively, over the base PCM. The highest average specific heat capacity (Cp) values in the solid and liquid phases were 1.98 J/g·°C and 2.69 J/g·°C, respectively, for the 2 % nanoparticle-additive sample. DSC analysis indicated slight shifts in phase transition temperatures and a noticeable reduction in latent heat values, from 215 J/g to 202 J/g for solidification and from 209 J/g to 201 J/g for melting. Computational analysis using ANSYS-FLUENT software validated the enhanced thermal dissipation properties of the nanocomposite PCM. Additionally, an examination of fin configurations within the PCM containers revealed that rectangular fins provided superior cooling efficacy compared to trapezoidal ones. This study demonstrates that the development of nano- Y2O3 enhanced MA nanocomposite PCMs presents a promising avenue for applications in electronic device thermal management and thermal energy storage.

Highly textured CMOS-compatible hexagonal boron nitride-based neuristor for reservoir computing

Significant advancements in artificial neural networks (ANNs) have driven the rapid progress of artificial intelligence and machine learning. While current feedforward neural networks primarily handle static data, recurrent neural networks (RNNs) are designed for dynamical systems. However, RNNs demand extensive training on specific tasks, limiting their scalability and affordability for edge computing. Physical reservoir computing (RC) offers an alternative approach by mapping inputs into high-dimensional states, allowing for pattern analysis within a fixed reservoir. Unlike RNNs, RC is well-suited for temporal and sequential data processing with rapid speed and low training costs. This makes RC suitable for hardware implementation across various research domains. Nonetheless, existing demonstrations of RC remain constrained to small-scale device arrays. As electronic synapse arrays aim to approach very large-scale and highly complex hardware as in the human brain, managing heat dissipation becomes a formidable challenge. In this work, we successfully developed the neuristors based on textured h-BN films, prepared using a CMOS-compatible technique, and constructed a physical RC system based on as-fabricated devices. Our approach leverages vertically aligned BN to provide aligned diffusion paths for the reproducible migration process of metal ions from the electrodes and offers a potential solution for thermal management in electronic devices. This achievement highlights the promising potential of our neuristors for future high-density and energy-efficient neuromorphic computing.

Study of impact of nano fluids on performance of microchannel heat exchangers using CFD

Addressing the critical issue of heat generation in electronic devices due to miniaturization and higher power density is essential. As electronic components become more compact, they generate more heat flux, necessitating efficient thermal management solutions. Traditional methods and fluids, such as water, struggle to meet the demand for efficient heat dissipation. To address this challenge, the utilization of nanofluids presents a promising solution. The objective of this study is to use CFD methods to examine how a nanofluid can improve heat transmission and lower the maximum temperature in a microchannel heatsink. This article presents the study of microchannel heatsinks with two distinct channel counts (five and eight). A constant flow, incompressible, laminar model was used to verify the findings. The working fluids used in the study were water in various concentrations, water-based nanofluids of Fe3O4-water and MWCNTs. CFD simulations revealed that a MWCNT-water nanofluid at 0.2 % concentration significantly improved cooling performance compared to water, demonstrating the potential of nanofluids for efficient thermal management in electronic devices.

ZnO nanostructure as an efficient heat spreader in electronic packaging

The purpose of this study is to reduce the material and increase the heat transfer performance for efficient thermal management in electronic devices. Consequently, various types of ZnO nanostructures were synthesized using various zinc acetate dihydrate (ZAD) concentrations (0.001 M, 0.01 M & 0.1 M) and the number of layers (6, 7 & 8), followed by annealing at 350 °C for 1 hr. The various nanostructures such as nano-walls (NWs), nano-leaves (NLs), and nanoflakes (NFs) were observed due to the formation of more aggregation of ZnO nucleation centers at various ZAD concentrations. Surface analysis showed decreased roughness (0.168 to 0.14 μm) with increased concentration and increased roughness (0.14 to 0.32 μm) with an increased number of layers. Among the nanostructures produced, the ZnO NW structure from 0.1 M solution with 7 layers effectively conducted the heat by observing a low LED temperature of 34.48 °C at 0.8 W.The surface quality was examined with an Atomic Force Microscope (AFM) and showed decreased roughness from 0.168 μm to 0.14 μm with increased concentration and increased roughness from 0.14 μm to 0.32 μm with an increased number of layers. The heat-spreading behavior of each nanostructure was evaluated by an infrared (IR) thermal imaging camera and displayed the surface-dependent heat distribution concerning the Zn concentration, number of layers, and testing current. Among the nanostructures produced, the ZnO NW structure prepared using 0.1 M ZAD solution with 7 layers effectively conducted the heat via through- and in-plane direction, which was proved by observing a low LED temperature of 34.48 °C at 0.8 W. Overall, ZnO nanostructures, especially NWs, offer promising potential for thermal management due to their unique properties at high power density. Consequently, ZnO nanostructures would be considered thermally efficient heat spreaders in electronic devices.

Active cooling of hot integrated circuits using a rotating cylinder and NEPCM-water mixture: Numerical analysis of the impact of phase change and Magnetohydrodynamics on double-diffusive mixed convection

Efficient cooling of integrated circuits is crucial for maintaining optimal performance and longevity of electronic devices. This study addresses this challenge by investigating the double-diffusive mixed convection around a hot integrated circuit (using) a nano-encapsulated phase change material-water mixture for enhanced heat absorption. The cooling process is carried out by a cylinder rotating at a constant speed inside a square cavity surrounded by the NEPCM-water mixture. Using the Galerkin finite element method, we numerically analyzed the influence of various parameters, including the Reynolds number (10≤Re≤100), Richardson number (0.1≤Ri≤10), Hartmann number (0≤Ha≤80), NEPCM volume fraction (0.01≤ϕ≤0.035), Lewis number (0.1≤Le≤10), buoyancy ratio (1≤Nz≤5), fusion temperature (0.1≤ϴf≤0.9), and Stefan number (0.1≤Ste≤0.8), on the average Nusselt number (Nuav), average Sherwood number (Shav), total entropy generation (Stotal), and Bejan number (Be). The results demonstrate that increasing Re and Ri enhances Nuav and Shav by up to 175 % and 162 %, respectively, while applying a magnetic field (increasing Ha) suppresses heat and mass transfer rates by up to 58 % and 50 %, respectively. Increasing ϕ improves Nuav by up to 34 % with minimal impact on Shav. The Le and Nz govern the coupling between heat and mass transfer processes, with Le substantially influencing Shav and Nz affecting both Nuav and Shav. The ϴf exhibits a non-monotonic effect on Nuav, suggesting an optimal fusion temperature, while Ste shows an inverse relationship with Nuav. The Stotal is significantly influenced by Re, Ri, Ha, and ϕ, while Be is affected by Re, Ri, Ha, and ϕ to a lesser extent. These findings provide valuable insights into the complex interplay of forced and natural convection, magnetohydrodynamics, and NEPCMs in the active cooling of hot electrical elements. The results can be applied to optimize cooling system designs, potentially leading to more efficient and effective thermal management in electronic devices.

Density-controlled thermal and mechanical properties of vertically aligned graphite foam-based polymer composites

The problem of thermal management of electronic devices leads to high demand of thermal interface materials (TIMs) with high thermal conductivity (TC) and softness. In this work, graphite foam (GFoam) was used to fabricate silicon rubber (SR) matrix-based TIMs by stacking and vertical cutting method. The obtained 75 vol% GFoam(100)/SR shows a high through-plane TC of 330.33 W m−1 K−1 due to the vertically aligned graphite layers. A strong correlation between the properties of the composites and the density of the fillers is found, providing a new perspective to adjust the properties of the composites. Composites with different proportions of GFoam and graphite film (GF) were prepared to further enhance the mechanical properties without obvious sacrifice of the thermal management performance. We believe that the design principles proposed in this work will be important for developing high-performance thermal management materials.

MXene grafted porous carbon cloth with alumina for high thermal conductivity and EMI shielding effect

Thermal interface material (TIM) has a great potential for efficient heat management and safety of electronic devices. However, achieving high performance polymer-based TIM is still challenging because of its intrinsic thermal conductivity and weak mechanical properties. In particular, electromagnetic interference shielding effect (EMI SE) of polymer-based composites has a great attraction according to electronic devices have become ubiquitous, playing integral roles in everyday life in our increasingly interconnected world. Herein, a porous carbon cloth (CC) for use as a continuous thermally and electrically conductive template is prepared via a freeze-casting method, after which mxene (MX) is chemically grafted onto the CC surface. Then, the as-prepared MX-CC is used along with alumina (AO) to fill a poly vinyl alcohol (PVA) matrix in order to fabricate a thermally conductive film with electromagnetic interference (EMI) shielding properties. The resultant composite demonstrates remarkable characteristics, including an excellent EMI shielding effect of 28 dB, substantial tensile strength of 19 MPa, and impressive out of plane thermal conductivity (3.98 W/mK). When applied to a light-emitting diode (LED), the PVA/MX-CC/AO composite effectively manages heat, thereby resulting in a 49 °C reduction in the operating temperature. Therefore, the composites developed herein hold great promise for improving thermal management in electronic devices.

Flexible loofah sponge-based phase change composite for thermal protection and wearable thermal management

To address the escalating demand for sophisticated thermal management in electronics, energy batteries, and wearable devices, extensive research has been dedicated to developing shape-stabilized and highly thermally conductive phase change composites (PCCs). However, their inherent rigidity and limited flexibility pose significant challenges for practical applications. In response, we have engineered a novel and flexible PCC by integrating loofah sponge (LS) and styrene-isoprene-styrene block copolymer (SIS) as co-supporting framework with paraffin wax (PW) as heat storage medium, further enhanced with carbon nanotubes (CNTs). The process began with the vacuum adsorption of PW into an ammonia-softened LS, which forming a fibrous network. This was followed by the introduction of a mixed melt of SIS and PW, physically cross-linked and dispersed with CNTs, into the LS fibrous network. The composite was then cooled and shaped to produce the (final) PCC. The resultant PCC exhibited remarkable ductility with an elongation of approximately 780 % and a maximum tensile strength of ∼2 MPa. Furthermore, it maintained thermal reliability and dimensional stability over long-term usage, with a melting heat enthalpy as high as 146.4 J/g. This flexible PCC, which combines high latent thermal energy storage, temperature regulation, and thermally induced assembly properties, shows considerable promise for thermal protection and portable thermal management in electronic devices.

Investigations on the heat transfer performance of phase change material (PCM)-based heat sink with triply periodic minimal surfaces (TPMS)

During the operational process of electronic components, excessive heat generation results in significant temperature elevation. This elevated temperature poses a significant risk to their service life. Regarding the issue of efficient thermal management of electronic devices in enclosed spaces experiencing high heat flow, a thermal management scheme for electronic equipment using TPMS and a PCM-based heat sink is proposed. The apparent heat capacity method is employed to simulate the melting process of the PCM-based heat sink. The effects of structural parameters w1, w3, and C of TPMS structures on the heat transfer characteristics (including base temperature, liquid fraction, average cell temperature, and average heat transfer coefficient) of the PCM-based heat sink during the melting process are discussed. A temperature testing platform is established. Experimental research is performed to investigate the effect of TPMS structures with two different printing prototypes (Sample 1, and Sample 2) on the heat sink during the intermittent cycle. The results indicate that increasing the parameters C and w1 significantly improves the average heat transfer coefficient (HTC) of the heat sink. When C increases from 0.3 to 0.7, the average HTC increases from 307 W/(m2·K) to 358 W/(m2·K). When w1 increases from 1 to 3, the average HTC increases from 284.5 W/(m2·K) to 321.3 W/(m2·K). Sample 1, possessing superior thermal conductivity, exhibits better heat transfer performance. When the temperature achieves a stable periodic variation, the base temperature of Sample 1 stabilizes within the range of 310 K-340 K. And Sample 2 stabilizes within the range of 315 K-350 K.

Experimental investigation of the melting heat transfer of phase change material-based heat sinks under mechanical agitation with a no-delay-start strategy

Phase change materials (PCMs) are commonly used for the thermal management of electronic devices, but their low thermal conductivity limits their suitability for higher heat fluxes and shorter heat storage/release durations. Existing studies on heat transfer enhancement have focused mainly on conduction and lack consideration of convection. Therefore, melting experiments on n-docosane under mechanical agitation (0–1600 RPM) were carried out. A no-delay-start strategy of agitation was achieved by submerging the paddle with the addition of water (200 and 400 mL). As the rotation speed (n) increases, the heating wall temperature (Tw) generally decreases, especially at 0–400 RPM. For 200 mL, Tw decreases by 31.2 °C from 0 to 1600 RPM at 3600 s; for 400 mL, the decrease is 29.2 °C at 5400 s. The temperature difference between the heating wall and PCM decreases remarkably under agitation, reaching only 2.7 and 1.7 °C for 200 and 400 mL, respectively, at 1600 RPM and 6300 s. The temperature field uniformity is also improved by agitation. In addition, with increasing n, the complete melting time (tc) generally decreases, while the holding time (thold) basically increases. Under agitation, the Tw values for 200 and 400 mL are generally lower than that for 0 mL, indicating that the no-delay-start strategy is feasible and advantageous. At n ≥ 800 RPM, Tw for 200 mL is greater than that for 400 mL throughout the entire melting process, while at n < 800 RPM, this trend occurs only during the solid-phase heat conduction stage. The effects of both the rotation speed and water volume depend on the combined function of the intensity of the PCM-water interface and the heat storage capacity of water. Even when the heat flux increases from 8.5 to 25.4 kW/m2, the thold can still be extended under agitation. The power consumption (Qc) of agitation increases with rotation speed, decreases with water volume, and exhibits less sensitivity to heat flux. It reaches a maximum value of 10 W at 1600 RPM. Considering factors such as Tw, thold and Qc, the optimal configuration is determined to be a water volume of 400 mL and a rotation speed of 1600 RPM. This study demonstrated that convection enhancement of PCMs with a no-delay-start strategy effectively addresses the thermal management challenges of electronic devices.

Adjustable temperature and high thermal conductivity composite phase change material based on sodium acetate trihydrate–alanine/expanded graphite for thermal management of electronic devices

Phase change energy storage technology using phase change materials (PCMs) is a viable solution to effectively address the heat dissipation problems of electronic devices. Herein, we proposed to prepare a modified PCM using CH3COONa·3H2O (SAT) as main PCM, 9 wt% DL-Alanine (DL) as temperature modifier, and 2 wt% Na2HPO4·12H2O as nucleating agent. Calculations using density functional theory method confirmed that the adjustment of DL on phase change temperature of SAT was originated from the hydrogen bond between them. Then, the modified PCM was loaded into 14 wt% expanded graphite (EG) to obtain a composite PCM with a suitable phase change temperature of 52.9 °C, phase change enthalpy of 227.4 J/g as well as supercooling degree of 6.6 °C, and the thermal conductivity of the composite PCM was as high as 11.52 W·m−1·K−1. SEM and pore structure analyses showed that the modified PCM was successfully loaded into the pore structure of EG, and their combination was verified by XRD and FT-IR as a physical interaction. After 200 heating–cooling cycles, the phase change temperature and enthalpy of the composite PCM was basically unchanged along with consistent crystal structure and chemical composition, showing an excellent thermal reliability. A comparative analysis applied in a testing system showed that with loading of the composite PCM temperature control module, the critical time of the electronic chip was extended by 4670 s and the thermal equilibrium temperature was decreased by 20.4 °C, presenting a good thermal management performance. Therefore, the prepared composite PCM had great potential for application in thermal management of electronic devices.

An Experimental and Numerical Studies of Fin-type Heat Sinks, Microchannel Heat Sink Its Cooling Performance and Design Consideration

Microchannel heat sinks (MCHS) have emerged as pivotal components in advanced thermal manage-ment systems due to their superior heat transfer capabilities. Fin-type heat sinks, essential for efficient thermal management in electronic devices, are evaluated through a series of experimental and numeri-cal studies. This paper reviews recent advancements in the design and performance analysis of various fin-type heat sinks, including micro pin-fins of different geometries and dimensions. By comparing the heat transfer efficiency and pressure drops among different designs and operating conditions, this re-view aims to provide insights into optimizing fin-type heat sinks for improved thermal management.

Polymeric Nanocomposites of Boron Nitride Nanosheets for Enhanced Directional or Isotropic Thermal Transport Performance.

Polymeric composites with boron nitride nanosheets (BNNs), which are thermally conductive yet electrically insulating, have been pursued for a variety of technological applications, especially those for thermal management in electronic devices and systems. Highlighted in this review are recent advances in the effort to improve in-plane thermal transport performance in polymer/BNNs composites and also the growing research activities aimed at composites of enhanced cross-plane or isotropic thermal conductivity, for which various filler alignment strategies during composite fabrication have been explored. Also highlighted and discussed are some significant challenges and major opportunities for further advances in the development of thermally conductive composite materials and their mechanistic understandings.

Development of copper-boron nitride core-shell structured fillers and surface treatment for thermally conductive composites

Core-shell structured copper-boron nitride (Cu@BN) spherical fillers were synthesized to fabricate thermally conductive composites. To enhance the interaction between the fillers and the matrix, polysilazane (PSZ) was coated on the surface of the filler. The resultant composite exhibited remarkable characteristics, including a substantial tensile strength of 32.36 MPa, excellent electrical insulation properties, and impressive thermal conductivity of 3.47 W/mK. When applied in a light-emitting diode (LED) application, the composite effectively managed heat, reducing the operating temperature by 34 °C. The epoxy/PSZ-Cu@BN composites hold great promise for improving thermal management in electronic devices.

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.