GeTe-based materials have attracted significant attention as high-efficiency thermoelectric materials for mid-temperature applications.However,GeTe thin-film materials with thermoelectric performances comparable to th...GeTe-based materials have attracted significant attention as high-efficiency thermoelectric materials for mid-temperature applications.However,GeTe thin-film materials with thermoelectric performances comparable to that of their bulk counterparts have not yet been reported,because of their unsatisfactory electrical and thermal properties caused by their poor crystal quality and high carrier concentration.Herein,a series of Sb-doped GeTe films and devices with remarkable thermoelectric performances are presented.These films are prepared through magnetron sputtering deposition at 553 K and exhibit a unique microstructure that consists of coarse-and fine-sized grains with high crystallization quality.The fine grains enhance the scattering associated with phonon transport and the coarse grains provide electron transport channels,which can suppress the thermal conductivity without obviously sacrificing the electrical conductivity.Moreover,Sb doping can effectively optimize the carrier concentration and increase the carrier effective mass,while introducing point defects and stacking faults to further scatter the phonon transport and decrease the thermal conductivity.Consequently,a peak power factor of 22.37μW cm−1 K−2 is obtained at 703 K and a maximum thermoelectric figure of merit of 1.53 is achieved at 673 K,which are substantially larger than the values reported in the existing literature.A flexible thermoelectric generator is designed and fabricated using Sb-doped GeTe films deposited on polyimide and achieves a maximum output power density of 2.22×103 W m−2 for a temperature difference of 300 K.展开更多
GeTe exhibits excellent p-type medium-temperature thermoelectric properties with low toxicity and good mechanical characteristics,making it highly promising for development in the thermoelectric field.However,GeTe is ...GeTe exhibits excellent p-type medium-temperature thermoelectric properties with low toxicity and good mechanical characteristics,making it highly promising for development in the thermoelectric field.However,GeTe is prone to producing Ge vacancies,leading to high p-type carrier concentration,which results in elevated electronic thermal conductivity and a low Seebeck coefficient.This study systematically analyzes intrinsic and extrinsic defects in GeTe and its alloys,focusing on reducing p-type carrier concentration through first-principles calculations.The results reveal that substituting Ge-sites with Bi(BiGe)yields lower donor defect formation energy,effectively reducing p-type carrier concentration of GeTe and its alloys compared to other elemental doping.Additionally,alloying with certain elements,such as Pb,proves favorable for decreased p-type carrier concentration due to lowered energy levels of valence band maximum(VBM).Inspired by this,screening divalent elements for alloying on Ge-sites reveals that Sr,Ba,Eu,and Yb substantially reduce the VBM of GeTe.Further calculations for Ba and Yb-alloyed GeTe confirm changes in formation energies for donor(favorable)and acceptor(unfavorable)defects.Our work provides a systematic investigation of intrinsic and various extrinsic doping defects in GeTe and its alloys,shedding light on possible strategies of optimizing carrier concentration in these compounds.展开更多
基金financial support from the Ministry of Science and Technology of China(Nos.2017YFA0700702,2017YFA0700705)the National Natural Science Foundation of China(Nos.52073290,51927803)+2 种基金the Liaoning Province Science and Technology Plan Project(2022-MS-011)the Science Fund for Distinguished Young Scholars of Liaoning Province(2023JH6/100500004)the Science and Technology Plan Projects of Shenyang(No.21108901).
文摘GeTe-based materials have attracted significant attention as high-efficiency thermoelectric materials for mid-temperature applications.However,GeTe thin-film materials with thermoelectric performances comparable to that of their bulk counterparts have not yet been reported,because of their unsatisfactory electrical and thermal properties caused by their poor crystal quality and high carrier concentration.Herein,a series of Sb-doped GeTe films and devices with remarkable thermoelectric performances are presented.These films are prepared through magnetron sputtering deposition at 553 K and exhibit a unique microstructure that consists of coarse-and fine-sized grains with high crystallization quality.The fine grains enhance the scattering associated with phonon transport and the coarse grains provide electron transport channels,which can suppress the thermal conductivity without obviously sacrificing the electrical conductivity.Moreover,Sb doping can effectively optimize the carrier concentration and increase the carrier effective mass,while introducing point defects and stacking faults to further scatter the phonon transport and decrease the thermal conductivity.Consequently,a peak power factor of 22.37μW cm−1 K−2 is obtained at 703 K and a maximum thermoelectric figure of merit of 1.53 is achieved at 673 K,which are substantially larger than the values reported in the existing literature.A flexible thermoelectric generator is designed and fabricated using Sb-doped GeTe films deposited on polyimide and achieves a maximum output power density of 2.22×103 W m−2 for a temperature difference of 300 K.
基金supported by the Natural Science Foundation of China(Grant Nos.52172216 and 92163212)the National Key Research and Development Program of China(No.2021YFB3502200)Shanghai Engineering Research Center for Integrated Circuits and Advanced Display Materials,Shanghai Technical Service Center of Science and Engineering Computing,Shanghai University,and Hefei Advanced Computing Center.
文摘GeTe exhibits excellent p-type medium-temperature thermoelectric properties with low toxicity and good mechanical characteristics,making it highly promising for development in the thermoelectric field.However,GeTe is prone to producing Ge vacancies,leading to high p-type carrier concentration,which results in elevated electronic thermal conductivity and a low Seebeck coefficient.This study systematically analyzes intrinsic and extrinsic defects in GeTe and its alloys,focusing on reducing p-type carrier concentration through first-principles calculations.The results reveal that substituting Ge-sites with Bi(BiGe)yields lower donor defect formation energy,effectively reducing p-type carrier concentration of GeTe and its alloys compared to other elemental doping.Additionally,alloying with certain elements,such as Pb,proves favorable for decreased p-type carrier concentration due to lowered energy levels of valence band maximum(VBM).Inspired by this,screening divalent elements for alloying on Ge-sites reveals that Sr,Ba,Eu,and Yb substantially reduce the VBM of GeTe.Further calculations for Ba and Yb-alloyed GeTe confirm changes in formation energies for donor(favorable)and acceptor(unfavorable)defects.Our work provides a systematic investigation of intrinsic and various extrinsic doping defects in GeTe and its alloys,shedding light on possible strategies of optimizing carrier concentration in these compounds.
