Hole Concentration Research Articles

(Invited) Understanding Photo-Driven Water Oxidation Mechanisms

Water oxidation is an important reaction that produces electrons and protons, which are important for downstream reactions such as hydrogen production and carbon dioxide reduction. Presently, the slow water oxidation is a key limiting factor for the development of hydrogen production and/or carbon dioxide reduction into practical solar energy storage technologies. An important reason for the slow progress in solve water oxidation problems is the lack of knowledge on the detailed mechanisms by which water is oxidized. As a multi-step process, the reaction involves at least 4 protons and 4 holes (when the desired product is oxygen gas). Intuitively, the coordination of charges and protons plays a critical role, but the details remain unknown. In this talk, we report our recent progress in understanding how water oxidation is influenced by surface hole behaviors. Using an Ir-based catalyst that features atomically defined structures, we were able to systematically vary a number of parameters, including the hole concentration, the density of active sites, as well as the properties of the supporting substrate that determines hole accumulation. It was found that matching the concentrations of surface holes and active site densities is critical. It was also revealed that the support substrate could have a profound influence on the reaction kinetics, even though they do not directly participate in the reactions. This knowledge is expected to propel the development of catalysts for improved water oxidation under photochemical conditions.

(Invited) Fundamentals of Plasmon-Induced Charge Transfer in Semiconducting Materials: Showcasing OER Catalysis

Using Localized Surface Plasmon Resonance Effect for Enhancing Electrochemical reactions has been reported earlier both in terms of direct electron injection/transfer (DET) in outer-sphere reductive processes as well as charge injection into semiconductors via plasmon-induced resonant electron transfer processes (PIRE). While the former (DET) is mainly influenced by the lifetimes of the ejected hot electrons and their rapid cooling at the interface. For inner sphere reductive processes via the LSPR phenomenon, direct charge injection into the LUMO states of the adsorbed species is required. In this regard, it is imperative to distinguish between the inter-band charge transfer of the adsorbed species because of exposure to photons.In contrast to these charge injections into semiconductors via plasmon-induced resonant electron transfer processes (PIRE), they must be more understood and complex. In this presentation, we will use the well-known endothermic anodic oxygen evolution reaction (OER) in alkaline pH to showcase the fundamental aspects of charge injection and its effect on the hole-driven OER mechanism. For this well-known OER catalyst, layered double hydroxides of Ni with Fe and Co dopants will be used. The electrochemical enhancement of OER will be explained based on detailed structural motifs of the semiconductors, its band structure, and the resonance effect of Au induced by the LSPR effect. Direct and indirect bandgaps will be discussed in the context of three possible mechanisms: (i) Charge carriers are directly injected into the semiconductor via LSPR. The semiconductor's conduction band is usually (-0.1 to 0.0 eV vs. NHE), and the valence band is between (2.00 and 3.5 eV), corresponding to electron energy between -2.00 to 3.5 eV vs. NHE. For LSPR nanoparticles, SPR energy is between 1.0 and 4.0 eV. Also, the Fermi energy of LSPR is usually 0.0 vs. NHE. Hence, LSPR only enables energetic electrons to be transferred from metals to semiconductors. It is the interface between LSPR and the semiconductor which is important. Charge injection is more prevalent when metal LSPR is of lower energy than the semiconductor—direct electron transfer (DET). (ii) Transfer does not involve direct electron injection but via (a) near-field electromagnetic and (b) resonant photon scattering mechanism. This has been shown to work by adding a thin dielectric material between the LSPR and the semiconductor. This would be most likely in the case of OER, where surface-localized plasmons will be the most important determinant instead of recombination events in the bulk of the semiconductor. This is most important for OER as it depends on the surface hole concentration. It should be noted that larger nanoparticles (>50 nm) have increased resonant photon scattering. Such a mechanism is more prevalent when we overlap metal LSPR and semiconductor bands, leading to plasmon-induced resonant electron transfer (PIRET). (iii) When metal LSPR is in direct contact with the semiconductor, all three phenomena could be active.

(Invited) Redox Chemistries for Vacancy Modulation in Copper Phosphide Nanocrystals

Copper phosphide has been proposed as an anode material for lithium-ion batteries due to the ability to accommodate the electrochemical insertion of Li ions without substantial reorganization of the P-sublattice. We present three copper-coupled redox chemistries that allow post-synthetic modulation of the delocalized hole concentrations in colloidal copper phosphide nanocrystals. Changes in the structural, optical, and compositional properties are evaluated by powder X-ray diffraction, electronic absorption spectroscopy, solid-state nuclear magnetic resonance spectroscopy and elemental analysis. The redox chemistries presented herein can be used to obtain nanocrystals with Cu/P ratios of ~2.66–2.93, a larger range than has been possible through purely synthetic tuning. Importantly, oxidation with a divalent metal halide and trioctylphosphine allows access to a uniquely Cu-deficient composition. Copper phosphide nanocrystal thin-films oxidized in this way would be ideal candidates for fundamental electrochemical lithiation studies.

Contact angle hysteresis on nonwetting microstructured surfaces: Effect of randomly distributed pillars or holes.

We present a numerical study of the advancing and receding apparent contact angles for a liquid meniscus in contact with an ultrahydrophobic surface with randomly distributed microsized pillars or holes in the Cassie's wetting regime. We study the Wilhelmy plate system in the framework of the full capillary model to obtain these angles using the heterogeneous surface approximation model for a broad interval of values of pillar or hole concentration and for both square and circular shapes of the pillars or holes cross-section. Three types of random placing of defects on the plate are investigated, i.e., two with restrictions: (1) with maximum and (2) with minimum distance between the defects (in these cases the defects are isolated), and (3) without restrictions (the defects can overlap). The results show that the type of defect distribution and also the type of the defects shape (circular or square) does not affect the magnitude of the two angles. The results of the numerical simulations showed that the retention force for a plate with randomly located defects is not greater, and for larger concentrations of pillars or holes, it is smaller than that for periodically spaced ones. Comparisons with experimental results for the receding contact angle on surfaces with pillars and with the advancing contact angle on surfaces with periodically arranged holes is carried out.

Real, imaginary and complex branches of Lamb waves in p-type piezoelectric semiconductor GaAs plate: Numerical and experimental investigation

First, we experimentally measure the concentration of holes of the piezoelectric semiconductor (PSC) Gallium arsenide (GaAs) material based on the Hall effect measurement. We then numerically calculate the Lamb wave characteristics in a p-type PSC GaAs plate using this measured value of the concentration of holes (estimated at approximately p0=3.5431×1025m−3). To guarantee the coupling effect that makes the Lamb wave a piezo-active wave, the GaAs crystal is oriented in a specific orientation of (110) plane. Ordinary differential equation (ODE) method is employed to calculate the dispersion curves, 3D view of the mechanical displacements, 3D view of the electric potential and 3D view of the concentrations of holes. Results show that the appearance of the complex branches of the Lamb modes coincides with the vanishing of the imaginary part of the wavevector (Im(k1)) to zero, which is a very remarkable finding that has not been discussed in previous studies. Meanwhile, these complex branches start exactly at the point of Zero-group-velocity (ZGV). Moreover, the present work highlights the hole drift characteristics of PSC GaAs and provides a critical comparative discussion with those published by (Zhu et al., 2018) for the PSC ZnO plate. Accordingly, the “Screening effect” phenomenon that is based on the positive holes in the negative electric potential region is discussed. The present results provide a theoretical and fundamental guidance on the development of smart devices based on the PSC GaAs material.

Structural, optical and electrochemical properties of Sr-doped ZnO nanoparticles

The Sr-doped ZnO nanoparticles have been synthesized by the chemical precipitation method at room temperature. The prepared nanoparticles are annealed at 500 °C for 4 h. The nanoparticles have been characterized using X-ray diffraction (XRD) technique, scanning electron microscope and UV–Vis spectroscopy. The XRD studies reveal the formation of a wurtzite geometry. The crystallite size, dislocation density and strain are examined as a function of Sr-doping concentration. The band gap of the prepared nanoparticles ranges from 3.46 eV to 3.56 eV. The nanoparticles have a higher hole concentration than electron concentration. Supercapacitor cells have been prepared by using synthesized nanoparticle electrodes and it is characterized using cyclic voltammetry (CV) by using KOH as an electrolyte solution. The calculated specific capacitance is high at a high doping concentration of ‘Sr’.

Milliseconds Thermal Processing of Boron Hyperdoped Germanium

P‐type hyperdoped germanium (Ge) has attracted significant attention for the development of superconducting semiconductors. However, the limited solid solubility of acceptors, especially boron (B), in Ge makes hyperdoping challenging. Herein, a systematic study on the electrical properties of boron‐implanted germanium is presented with an atomic concentration beyond 10 at%. The B‐implanted Ge was annealed by millisecond flash lamp annealing (ms‐FLA) with different parameters. The results indicate that millisecond solid phase epitaxy ensures the electrical activation of B much above the solubility limit with hole concentration as high as 2 × 1021 cm−3 and low‐temperature sheet resistance of 13 Ω sq−1 which is promising for superconductivity. It is also shown that millisecond annealing effectively suppresses the B diffusion and provides much higher activation efficiency of acceptors compared to conventional annealing methods.

Effect of deposition cycle and annealing on the structural, optical, electrical, and photoluminescence properties of SnS films obtained from rapid S-SILAR technique

AbstractIn this paper, we present an optimized procedure for depositing SnS thin films using the rapid S-SILAR technique. We also analyze the effects of deposition cycles and post-deposition annealing on various film properties. XRD analysis indicates the presence of orthorhombic and cubic phases in the films. Energy dispersive X-ray analysis confirms near-optimal stoichiometry. SEM images depict the growth of closely spaced spherical granules. High optical absorption is observed in the mid-visible to NIR region, with the absorption edge shifting towards the NIR region after annealing. The bandgap values range from 1.6 eV to 1.9 eV, which is ideal for photovoltaic applications. PL spectra show three clusters of peaks corresponding to red and green emissions. Hall measurements confirm that both the as-deposited and annealed SnS films exhibit p-type conductivity, with a hole concentration on the order of 1015 cm−3.

Dual polarization for efficient III-nitride-based deep ultraviolet micro-LEDs

The deep ultraviolet (DUV) micro-light emitting diode (μLED) has serious electron leakage and low hole injection efficiency. Meanwhile, with the decrease in the size of the LED chip, the plasma-assisted dry etching process will cause damage to the side wall of the mesa, which will form a carrier leakage channel and produce non-radiative recombination. All of these will reduce the photoelectric performance of μLED. To this end, this study introduces polarized bulk charges into the hole supply layer (p-HSL) and the electron supply layer (n-ESL) respectively (dual-polarized structure) of the DUV μLED at an emission wavelength of 279 nm to enhance the binding of carriers and increase the injection efficiency of carriers. This is because the polarization-induced bulk charge can shield the polarized sheet charge on the interface and reduce the polarization electric field. The reduced polarization electric field in p-HSL can increase the effective barrier height of the conduction band in the p-type region and reduce the effective barrier height of the valence band. The decrease in the polarized electric field of n-HSL can reduce the thermal velocity of electrons, thereby enhancing the electron injection efficiency, reducing the Shockley–Read–Hall (SRH) recombination, and increasing the effective barrier height of the valence band. The study results indicate that the electron concentration and hole concentration of a μLED with dual polarization were increased by 77.93% and 93.6%, respectively. The optical power and maximum external quantum efficiency of μLED reached 31.04 W/cm2 and 2.91% respectively, and the efficiency droop is only 2.06% at 120 A/cm2. These results provide a new approach to solving the problem of insufficient carrier injection and SRH recombination in high-performance DUV μLEDs.

Achievable hole concentration at room temperature as a function of Mg concentration for MOCVD-grown p-GaN after sufficient annealing

Relationship between the hole concentration at room temperature and the Mg doping concentration in p-GaN grown by MOCVD after sufficient annealing was studied in this paper. Different annealing conditions were applied to obtain sufficient activation for p-GaN samples with different Mg doping ranges. Hole concentration, resistivity and mobility were characterized by room-temperature Hall measurements. The Mg doping concentration and the residual impurities such as H, C, O and Si were measured by secondary ion mass spectroscopy, confirming negligible compensations by the impurities. The hole concentration, resistivity and mobility data are presented as a function of Mg concentration, and are compared with literature data. The appropriate curve relating the Mg doping concentration to the hole concentration is derived using a charge neutrality equation and the ionized-acceptor-density [ ] (cm−3) dependent ionization energy of Mg acceptor was determined as = 184 − 2.66 × 10−5 × [ ]1/3 meV.

High performance ambipolar response photodetectors based on ReS2/PdSe2 van der Waals heterostructures

Anomalous negative photoresponse in a photodetector where the current is reduced under light illumination holds great potential in the application of next-generation novel and multifunctional optoelectronic devices. Until now, the figure of merits for negative photodetectors, such as responsivity and response speed, still exhibit unsatisfactory performance when compared to their positive counterparts. In this work, an unique gate voltage-dependent ambipolar-response photodetector based on the ReS2/PdSe2 heterostructure with excellent characteristics are prepared and investigated systematically. The evolution for concentration of hole in PdSe2 by gate voltage and the trap states existed at the surface and interface play a dominant role in the transition of negative to positive response. The negative photoresponse performances in terms of responsivity, external quantum efficiency (EQE), and response speed under 638 nm light illumination, are as high as about 532 A/W, 105%, and as fast as 7.9/8.7 µs, respectively. Meanwhile, the corresponding values of the positive response also reach to ∼10.5 A/W, ∼2069 %, and ∼30 µs, respectively, demonstrating the superiority of this heterostructure at ambipolar response. In addition, a similar phenomenon is also observed at the near-infrared region (980 nm). The discovery of these results signifies a pronounced breakthrough in the field of ambipolar photodetectors, thereby paving the way for future advancements in optoelectronic applications.

Large-area and few-layered 1T′-MoTe2 thin films grown by cold-wall chemical vapor deposition

This study employs cold-wall chemical vapor deposition to achieve the growth of MoTe2 thin films on 4-inch sapphire substrates. A two-step growth process is utilized, incorporating MoO3 and Te powder sources under low-pressure conditions to synthesize MoTe2. The resultant MoTe2 thin films exhibit a dominant 1T′ phase, as evidenced by a prominent Raman peak at 161 cm−1. This preferential 1T′ phase formation is attributed to controlled manipulation of the second-step growth temperature, essentially the reaction stage between Te vapor and the pre-deposited MoO x layer. Under these optimized growth conditions, the thickness of the continuous 1T′-MoTe2 films can be precisely tailored within the range of 3.5–5.7 nm (equivalent to 5–8 layers), as determined by atomic force microscopy depth profiling. Hall-effect measurements unveil a typical hole concentration and mobility of 0.2 cm2 Vs−1 and 7.9 × 1021 cm−3, respectively, for the synthesized few-layered 1T′-MoTe2 films. Furthermore, Ti/Al bilayer metal contacts deposited on the few-layered 1T′-MoTe2 films exhibit low specific contact resistances of approximately 1.0 × 10−4 Ω cm2 estimated by the transfer length model. This finding suggests a viable approach for achieving low ohmic contact resistance using the 1T′-MoTe2 intermediate layer between metallic electrodes and two-dimensional semiconductors.

Hierarchical Solid-Additive Strategy for Achieving Layer-by-Layer Organic Solar Cells with Over 19 % Efficiency.

Layer-by-layer (LbL) deposition of active layers in organic solar cells (OSCs) offers immense potential for optimizing performance through precise tailoring of each layer. However, achieving high-performance LbL OSCs with distinct solid additives in each layer remains challenging. In this study, we explore a novel approach that strategically incorporates different solid additives into specific layers of LbL devices. To this end, we introduce FeCl3 into the lower donor (D18) layer as a p-type dopant to enhance hole concentration and mobility. Concurrently, we incorporate the wide-band gap conjugated polymer poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) into the upper acceptor (L8-BO) layer to improve the morphology and prolong exciton lifetime. Unlike previous studies, our approach combines these two strategies to achieve higher and more balanced electron and hole mobility without affecting device open-circuit voltage, while also suppressing charge recombination. Consequently, the power conversion efficiency (PCE) of the D18+FeCl3/L8-BO device increases to 18.12 %, while the D18/L8-BO+PFO device attains a PCE of 18.79 %. These values represent substantial improvements over the control device's PCE of 17.59 %. Notably, when both FeCl3 and PFO are incorporated, the D18+FeCl3/L8-BO+PFO device achieves a remarkable PCE of 19.17 %. In summary, our research results demonstrate the effectiveness of the layered solid additive strategy in improving OSC performance.

Hierarchical Solid‐Additive Strategy for Achieving Layer‐by‐Layer Organic Solar Cells with Over 19 % Efficiency

AbstractLayer‐by‐layer (LbL) deposition of active layers in organic solar cells (OSCs) offers immense potential for optimizing performance through precise tailoring of each layer. However, achieving high‐performance LbL OSCs with distinct solid additives in each layer remains challenging. In this study, we explore a novel approach that strategically incorporates different solid additives into specific layers of LbL devices. To this end, we introduce FeCl3 into the lower donor (D18) layer as a p‐type dopant to enhance hole concentration and mobility. Concurrently, we incorporate the wide‐band gap conjugated polymer poly(9,9‐di‐n‐octylfluorenyl‐2,7‐diyl) (PFO) into the upper acceptor (L8‐BO) layer to improve the morphology and prolong exciton lifetime. Unlike previous studies, our approach combines these two strategies to achieve higher and more balanced electron and hole mobility without affecting device open‐circuit voltage, while also suppressing charge recombination. Consequently, the power conversion efficiency (PCE) of the D18+FeCl3/L8‐BO device increases to 18.12 %, while the D18/L8‐BO+PFO device attains a PCE of 18.79 %. These values represent substantial improvements over the control device′s PCE of 17.59 %. Notably, when both FeCl3 and PFO are incorporated, the D18+FeCl3/L8‐BO+PFO device achieves a remarkable PCE of 19.17 %. In summary, our research results demonstrate the effectiveness of the layered solid additive strategy in improving OSC performance.

Improving the efficiency above 35 % of MoS2-based solar cells by through optimization of various wide-bandgap S-chalcogenides ETL

Molybdenum disulfide (MoS2)-based photovoltaic cells are increasingly attracting researchers’ due to their outstanding semiconducting properties. Single junction MoS2 based solar cell have been investigated with three distinct electron transport layer (ETL) layers made of SnS2, In2S3 and ZnSe in detail with and without back surface field (BSF). A thorough numerical analysis has been conducted of the effects of band alignment, defect density, absorber layer thickness, buffer layer thickness, interface defect density, electron and hole concentration, generation and recombination, open circuit voltage (VOC), short circuit current (JSC), fill factor (FF), and power conversion efficiency (PCE) via SCAPS-1D simulation software. The MoS2 based solar cell produced the photo conversion efficiency (PCE) of 24.77 % with VOC of 0.913 V, JSC of 31.274 mA/cm2, and FF of 86.77 % without BSF. On the other hand, after in depth analysis, according to simulation results, SnS2 ETL produced the highest PCE of 35.60 % than ZnSe(33.56 %) and In2S3(34.94 %) ETL with VOC of 1.07 V, JSC of 37.55 mA/cm2, and FF of 88.80 % with inserting only 30 nm V2O5 BSF layer. The suggested research might provide information and a workable strategy for producing a MoS2-based thin-film solar cell that is affordable.

Temperature Effects on GaN/AlN Heterojunction in a Piezomagnetic and Piezoelectric Semiconductor Composite Fiber

In this article, considering the thermal effects, a PN GaN/AlN heterojunction in a piezomagnetic and piezoelectric semiconductor composite fiber driven by dynamic magnetic loads is studied. The true nonlinear constitutive equations of the electric current density for the composite heterojunction are employed. Thus, a nonlinear finite‐element method (FEM) is adopted to obtain dynamic responses of the composite heterojunction, including the mechanical displacement, electric potential, and electron and hole concentrations. By comparing dynamic responses with those derived by COMSOL Multiphysics, the nonlinear FEM is verified. Based on numerical results, regulation effects of the temperature on distributions of the mechanical displacement, electron and hole concentrations, and temperature–current–voltage characteristics are discussed.

The Hydroxylated Carbon Nanotubes as the Hole Oxidation System in Electrocatalysis.

The hydroxylated carbon nanotubes (CNTs-OH), due to their propensity to trap electrons, are considered in many applications. Despite many case studies, the effect of the electronic structure of the CNT-OH electrode on its oxidation properties has not received in-depth analysis. In the present study, we used Fe(CN)63-/4- and Ru(NH3)63+/2+ as redox probes, which differ in charge. The CNT-OH and CNT electrodes used in the cyclic voltammetry were in the form of freestanding films. The concentration of holes in the CNTs-OH, estimated from the upshift of the Raman G-feature, was 2.9×1013 cm-2. The standard rate constant of the heterogeneous electron transfer (HET) between Fe(CN)63-/4- and the CNTs-OH electrode was 25.9×10-4 cm·s-1. The value was more than four times higher than the HET rate on the CNT electrode (ks=6.3×10-4 cm·s-1), which proves excellent boosting of the redox reaction by the holes. The opposite effect was observed for the Ru(NH3)63+/2+ redox couple. While the redox reaction rate constant at the CNT electrode was 1.4×10-4 cm·s-1, there was a significant suppression of the redox reaction at the CNT-OH electrode (ks<0.1×10-4 cm·s-1). Based on the DFT calculations and the Gerischer model, we find that the boosting of the HET from the reduced form of the redox couple to CNT-OH occurs when the reduced forms of the redox couples are negatively charged and the occupied reduced states are aligned with acceptor states of the nanotube electrode.

Effect of hydrogen poisoning on p-gate AlGaN/GaN HEMTs

In this work, we investigate the degradation behavior and mechanism of p-gate AlGaN/GaN high-electron mobility transistors (HEMTs) for the first time under hydrogen (H2) atmosphere. The experimental results reveal significant decrease in drain-to-source current, negative drift in threshold voltage, increase in off-state gate leakage current, and deterioration of subthreshold swing in the p-gate AlGaN/GaN HEMT after H2 treatment. The degradation of the electrical parameters is considered to hydrogen poisoning phenomenon. Through secondary ion mass spectrometry and variable temperature photoluminescence spectroscopy, we observe the increase in hydrogen concentration in the p-GaN layer and the formation of electrically inactive Mg–H complexes after H2 treatment. As results, the effective hole concentration decreases and the trap density of the device increases, which are confirmed by Hall effect measurement and low-frequency noise analysis, respectively. The detrimental effect of hydrogen on p-gate AlGaN/GaN HEMTs can be attributed primarily to the compensation of Mg doping and the generation of defects.

Thermoelectric Performance Enhancement in SnS Polycrystals Owing to Hole Doping Combined with Textured Microstructures.

Recently, the earth-abundant tin sulfide (SnS) has emerged as a promising thermoelectric material due to its phonon and electron structure similar to that of tin selenide (SnSe). However, compared with SnSe, limited progress has been achieved in the thermoelectric property enhancement of SnS. Textured SnS polycrystals with an enhanced thermoelectric performance have been developed in this work. The high carrier mobility benefited from the enhanced texture through the repressing strategy of spark plasma sintering, improving the electrical conductivity. In addition, Sn atom deficiencies in the texture sample led to an increased hole concentration, further boosting the electrical conductivity and power factor. The power factor exceeded 4.10 μW/cm·K2 at 423 K and 5.50 μW/cm·K2 at 850 K. The phonon scattering was strengthened by adjusting the multiscale microstructures including dislocations, defect clusters, etc., leading to an ultralow lattice thermal conductivity of 0.23 W/m·K at 850 K. A figure of merit zT > 1.3 at 850 K and an average zTave of 0.58 in the temperature range 373-850 K were achieved in the SnS polycrystal.

Defect Engineering Realizes Superior Thermoelectric Performance of GeTe

AbstractGeTe has been considered as a promising mid‐temperature thermoelectric (TE) candidate, but its zT value is severely limited by the excessive hole concentration and high thermal conductivity. Here, it is demonstrated that the TE properties of GeTe can be significantly improve by defect engineering of Sb‐Pb and AgCuTe codoping. The Sb‐Pb codoping is adopted to optimize the carrier concentration and manipulate the rhombohedral lattice distortion, leading to valence band convergence and enhanced power factor. The AgCuTe alloying introduces multiscale phonon scattering centers including dislocations and nano‐precipitates to reduce the lattice thermal conductivity in GeTe. Consequently, a maximum zT of 2.3 at 773 K and an average zT of 1.43 (300–773 K) are obtained in (Ge0.84Sb0.06Pb0.1Te)0.99(AgCuTe)0.01. Moreover, the fabricated thermoelectric module exhibits a high output power density of 0.59 W cm–2 and an energy conversion efficiency of 7.9% at ΔT = 500 K, suggesting hierarchical defect engineering is an effective strategy to realize high‐performance GeTe‐based thermoelectric.