Thin film thermoelectric devices for power conversion and cooling

Abstract

A thermoelectric device having at least one thermoelectric unit including at least one thermoelectric pair of n-type and p-type thermoelements, a first header coupled to one side of the thermoelectric pair, and a second header coupled to a second side of the thermoelectric pair. The thermoelectric pair has a thermal conduction channel area smaller than an area of the first header or the second header such that the thermal conduction area is a fraction of the area of the first header or the second header.

1 . A thermoelectric device comprising:
 at least one thermoelectric unit comprising, a plurality of thermoelectric pairs of n-type and p-type thermoelements, a first header coupled to one side of the thermoelectric pairs, a second header coupled to a second side of the thermoelectric pairs, and all of said plurality of thermoelectric pairs between the first and second headers defining a thermal conduction channel area through all of the plurality of thermoelectric pairs that is smaller than an area of at least one of the first header and the second header adjacent the plurality of thermoelectric pairs such that the thermal conduction channel area is a fraction of the area of said at least one of the first header and the second header adjacent the plurality of thermoelectric pairs, and wherein said fraction is less than 0.5%.   
     
     
         2 .- 5 . (canceled) 
     
     
         6 . The device of  claim 1 , further comprising:
 a thermal impedance increasing device disposed between the thermoelectric pair and one of said first and second headers and configured to set a thermal impedance across a gap between the first and second headers to be at least comparable to a thermal impedance across said thermoelectric pair.   
     
     
         7 . The device of  claim 6 , wherein the thermal impedance increasing device comprises:
 a heat pipe disposed between one of said first and second headers, coupled to said thermoelectric pair, and elongated in a transverse direction to space apart the first header from the second header.   
     
     
         8 . The device of  claim 7 , wherein the heat pipe comprises:
 a metal member disposed between said thermoelectric pair and one of said first and second headers, extending in said transverse direction, and having a width comparable to a width of the thermoelectric pair.   
     
     
         9 . The device of  claim 7 , wherein said heat pipe is configured to separate said first header from said second header by a distance such that a thermal impedance across a gap between the first and second headers is at least comparable to a thermal impedance across the thermoelectric pair. 
     
     
         10 . The device of  claim 9 , wherein said distance is at least 100 to 500 μm. 
     
     
         11 . The device of  claim 9 , wherein said distance is at least 10 μm. 
     
     
         12 . The device of  claim 6 , wherein the thermal impedance increasing device comprises:
 an evacuated housing enclosing the thermoelectric pair and said one of the first and second headers.   
     
     
         13 . The device of  claim 12 , wherein said housing comprises a vacuum level of no greater that 1 Torr. 
     
     
         14 . The device of  claim 6 , wherein the thermal impedance increasing device comprises:
 a housing enclosing the thermoelectric pair and said one of the first and second headers, said housing filled with a low thermal conductivity medium to reduce a thermal impedance across a gap between the first and second headers to be at least comparable to a thermal impedance across the thermoelectric pair.   
     
     
         15 . The device of  claim 14 , wherein said low thermal conductivity medium comprises Ar gas. 
     
     
         16 . The device of  claim 1 , wherein said thermoelectric pair, upon conduction of said heat through the thermoelements, produces an electrical potential. 
     
     
         17 . The device of  claim 1 , wherein said thermoelectric pair, upon a current flow through the thermoelements, cools said first header. 
     
     
         18 . The device of  claim 1 , further comprising:
 electrical connections to said thermoelectric pair, having a resistance less than 1/10 th  of an Ohmic resistance of the thermoelectric pair.   
     
     
         19 . The device of  claim 18 , wherein said electrical connections comprise metal connections. 
     
     
         20 . (canceled) 
     
     
         21 . The device of  claim 1 , wherein said thermoelectric pair comprises:
 a thermoelectric material having a figure of merit of at least 1.   
     
     
         22 . The device of  claim 1 , wherein said thermoelectric pair comprises:
 a thermoelectric material having a figure of merit of at least 2.   
     
     
         23 . The device of  claim 1 , wherein said thermoelectric pair comprises:
 at least one of a superlattice and a quantum dot superlattice.   
     
     
         24 . The device of  claim 23 , wherein said superlattice comprises:
 at least one of a Bi 2 Te 3 /Sb 2 Te 3  superlattice, a Si/Ge superlattice, and a PbTe/PbSe superlattice.   
     
     
         25 . The device of  claim 1 , wherein at least one of said first header and second header comprises:
 a thermally conducting member.   
     
     
         26 . The device of  claim 25 , wherein the thermally conducting member comprises:
 an electrically conducting member and an electrical insulation member formed on the electrically conducting member; and   a patterned conductor formed on the electrical insulation member and connecting to said thermoelectric pair.   
     
     
         27 . The device of  claim 26 , wherein said electrically conducting member comprises at least one of Al, Cu, doped Si, and doped SiC. 
     
     
         28 . The device of  claim 26 , further comprising:
 plural thermoelectric pairs connected in series by said patterned conductor.   
     
     
         29 . The device of  claim 25 , wherein the thermally conducting member comprises:
 an electrically insulating plate; and   a patterned conductor provided on the electrically insulating plate and connecting to said thermoelectric pair.   
     
     
         30 . The device of  claim 29 , wherein said electrically insulating plate comprises at least one of AIN, SiC, Si, and diamond. 
     
     
         31 . The device of  claim 29 , further comprising:
 plural thermoelectric pairs connected in series by the patterned conductor.   
     
     
         32 . The device of  claim 7 , wherein the heat pipe has a thermal conduction channel area that is smaller than an area of said one of the first header and the second header. 
     
     
         33 . The device of  claim 7 , wherein the heat pipe comprises a heat pipe having a temperature drop of less than 5 K for heat fluxes in a range about 25 W/cm 2 . 
     
     
         34 . The device of  claim 7 , wherein the heat pipe comprises a heat pipe coupled to said thermoelectric pair and said one of the first and second headers by a metal bond. 
     
     
         35 . The device of  claim 34 , wherein the metal bond comprises at least one of a solder-bump-bond, a friction bond, and a reactive-metal bond. 
     
     
         36 . The device of  claim 7 , wherein the heat pipe comprises a radiative coupling mechanism coupling heat from the heat pipe to at least one of said first header, said thermoelectric pair, and said second header. 
     
     
         37 . The device of  claim 36 , wherein the radiative coupling mechanism comprises a Purcell-enhancement cavity transmitter/receiver structure. 
     
     
         38 . The device of  claim 37 , wherein the Purcell-enhancement cavity transmitter/receiver structure comprises:
 a thermally conductive layer including dispersed therein one of metal, semimetal, and semiconductor particles.   
     
     
         39 . The device of  claim 37 , wherein the Purcell-enhancement cavity transmitter/receiver structure comprises:
 at least one of μm-size and sub-micron-size radiation fins configured to enhance spontaneous radiative heat transport.   
     
     
         40 . The device of  claim 1 , further comprising:
 a controller configured to control a current through said thermoelectric pair such that said thermoelectric device operates in at least one of a cooling mode, a heat pump mode, a power conversion mode, and a heat flux sensing mode.   
     
     
         41 . The device of  claim 40 , wherein said controller is configured in said heat flux sensing mode to measure said current through said thermoelectric pair. 
     
     
         42 . The device of  claim 1 , wherein said second header comprises:
 a body having slits formed partially through the body.   
     
     
         43 . The device of  claim 1 , wherein said second header comprises a material having a thermal conductivity higher than Cu. 
     
     
         44 . The device of  claim 1 , wherein said first header comprises:
 an integrated circuit element; and   a heat spreader disposed between said integrated circuit element and said thermoelectric pair.   
     
     
         45 . The device of  claim 1 , wherein said at least one thermoelectric unit is configured to have a specific power greater than 1 W/gm. 
     
     
         46 . The device of  claim 1 , wherein said at least one thermoelectric unit is configured to have a specific power in a range of 0.0001 W/gm to 0.01 W/gm. 
     
     
         47 . The device of  claim 46 , wherein the first header is coupled to a heat source in a range of 30-40° C. 
     
     
         48 . The device of  claim 1 , wherein said at least one thermoelectric unit is configured to produce a power density greater than 0.5 W/cm 2 . 
     
     
         49 . The device of  claim 1 , wherein said at least one thermoelectric unit is configured to produce a power density in a range from 0.0005-0.5 W/cm 2 . 
     
     
         50 . A thermoelectric device comprising:
 plural cascaded thermoelectric units, each unit including, a plurality of thermoelectric pairs of n-type and p-type thermoelements, a first header coupled to one side of the plurality of thermoelectric pairs, a second header coupled to a second side of the plurality of thermoelectric pairs, all of the plurality of thermoelectric pairs between the first and second headers defining a thermal conduction channel area smaller than an area of at least one of the first header and the second header and the thermal conduction channel area defining a packing fraction relative to an area of said at least one of the first header and the second header, wherein said packing fraction is less than 50%, wherein the plural cascaded thermoelectric units comprises first and second thermoelectric units thermally coupled in series between a heat source and a heat sink so that a temperature of a header between thermoelements of the first and second thermoelectric units is between a temperature of the heat source and a temperature of the heat sink during operation wherein a packing fraction in said at least one lower thermoelectric unit is less than 0.5%.   
     
     
         51 . The device of  claim 50 ,
 wherein the first thermoelectric unit comprises at least one upper thermoelectric unit coupled to the heat source;   wherein the second thermoelectric unit comprises at least one lower thermoelectric unit coupled to the at least one upper thermoelectric unit; and   wherein the heat sink is thermally coupled to the at least one lower thermoelectric unit and configured to dissipate heat from the at least one lower thermoelectric unit.   
     
     
         52 .- 54 . (canceled) 
     
     
         55 . The device of  claim 51 , wherein said thermoelectric pair in at least one of the at least one upper thermoelectric unit and the at least one lower thermoelectric unit comprises:
 at least one of Bi 2 Te 3 , Sb 2 Te 3 , SiGe, (AgSbTe 2 ) 1-x (GeTe) x , PbTe, PbSe, ZnSb, and skutterrudites.   
     
     
         56 . The device of  claim 55 , wherein the (AgSbTe 2 ) 1-x (GeTe) x  comprises a GeTe mole fraction of ˜0.80 to 0.85. 
     
     
         57 . The device of  claim 51 , wherein the at least one upper thermoelectric unit is configured to operate at temperatures from 670 K to 870 K. 
     
     
         58 . The device of  claim 51 , wherein the at least one lower thermoelectric unit is configured to operate at temperatures from 470 K to 670 K. 
     
     
         59 . The device of  claim 51 , wherein the at least one lower thermoelectric unit is configured to operate at temperatures from 300 K to 470 K. 
     
     
         60 . (canceled) 
     
     
         61 . The device of  claim 51 , wherein said plural cascaded thermoelectric units are configured to have a specific power in a range of 0.0001 W/gm to 0.01 W/gm. 
     
     
         62 . The device of  claim 61 , wherein the first header is coupled to said heat source in a range of 30-40° C. 
     
     
         63 . The device of  claim 51 , wherein said plural cascaded thermoelectric units are configured to produce a power density greater than 0.5 W/cm 2 . 
     
     
         64 . The device of  claim 51 , wherein said plural cascaded thermoelectric units are configured to produce a power density in a range of 0.0005 W/cm 2  to 0.5 W/cm 2 . 
     
     
         65 .- 67 . (canceled) 
     
     
         68 . A system for thermoelectric power conversion, comprising:
 a plurality of thermoelectric pairs of n-type and p-type thermoelements;   a first header coupled to one side of the plurality of thermoelectric pairs;   a second header coupled to a second side of the plurality of thermoelectric pairs;   all of said plurality of thermoelectric pairs between the first and second headers defining a thermal conduction channel area smaller than an area of at least one of the first header and the second header such that the thermal conduction channel area is a fraction of the area of said at least one of the first header and the second header, said fraction being less than 0.5%; and   a heat sink coupled to the second header and configured to dissipate heat at a rate which maintains a temperature of the second header below a temperature of the first header.   
     
     
         69 .- 72 . (canceled) 
     
     
         73 . The system of  claim 68 , further comprising:
 a coupling member coupling the first header to a heat source.   
     
     
         74 . The system of  claim 73 , wherein said coupling member comprises at least one of a steam pipe, a combustion exhaust pipe, and a thermally conducting member having a thermal conductance of at least Al and extending from said first header to said heat source. 
     
     
         75 . The system of  claim 68 , further comprising:
 a thermal impedance increasing device disposed between the thermoelectric pair and one of said first and second headers.   
     
     
         76 . The system of  claim 68 , further comprising:
 plural cascaded thermoelectric units, each comprising said first header, said thermoelectric pair, and said second header.   
     
     
         77 . The system of  claim 76 , wherein one of said plural cascaded thermoelectric units comprises:
 at least one upper thermoelectric unit coupled to a heat source;   at least one lower thermoelectric unit coupled to the at least one upper thermoelectric unit; and   a heat sink thermally coupled to the at least one lower thermoelectric unit and configured to dissipate heat from the at least one lower thermoelectric unit.   
     
     
         78 . The system of  claim 77 , wherein said thermoelectric pair in at least one of the at least one upper thermoelectric unit and the at least one lower thermoelectric unit comprises:
 at least one of Bi 2 Te 3 , Sb 2 Te 3 , SiGe, (AgSbTe 2 ) 1-x (GeTe) x , PbTe, PbSe, ZnSb, and skutterrudites.   
     
     
         79 . The system of  claim 78 , wherein the (AgSbTe 2 ) 1-x (GeTe) x  comprises a GeTe mole fraction of ˜0.80 to 0.85. 
     
     
         80 . The system of  claim 77 , wherein said thermoelectric pair in at least one of the at least one upper thermoelectric unit and the at least one lower thermoelectric unit comprises:
 at least one of a superlattice and a quantum dot superlattice.   
     
     
         81 . The system of  claim 80 , wherein said superlattice comprises:
 at least one of a superlattice of Si/Ge, PbTe/PbSe, ZnSb/CdSb, InAs/InSb, CdTe/HgCdTe, Ga x In 1-x As/Ga y In 1-y As.   
     
     
         82 . The system of  claim 77 , wherein the at least one upper thermoelectric unit is configured to operate at temperatures from 670 K to 870 K. 
     
     
         83 . The system of  claim 77 , wherein the at least one lower thermoelectric unit is configured to operate at temperatures from 470 K to 670 K. 
     
     
         84 . The system of  claim 77 , wherein the at least one lower thermoelectric unit is configured to operate at temperatures from 300 K to 470 K. 
     
     
         85 . The system of  claim 76 , wherein said plural cascaded thermoelectric units and said heat sink are configured to have a specific power greater than 1 W/gm. 
     
     
         86 . The system of  claim 76 , wherein said plural cascaded thermoelectric units are configured to have a specific power in a range of 0.0001 W/gm to 0.01 W/gm. 
     
     
         87 . The system of  claim 86 , wherein the first header is coupled to a heat source in a range of 30-40° C. 
     
     
         88 . The system of  claim 76 , wherein said plural cascaded thermoelectric units and said heat sink are configured to produce a power density greater than 0.5 W/cm 2 . 
     
     
         89 . The system of  claim 76 , wherein said plural cascaded thermoelectric units are configured to produce a power density in a range of 0.0005 W/cm 2  to 0.5 W/cm 2 . 
     
     
         90 . The device of  claim 50  wherein a packing fraction of all thermoelements of the first thermoelectric unit is different than a packing fraction of all the thermoelements of the second thermoelectric unit. 
     
     
         91 . The device of  claim 50  wherein a packing fraction of all thermoelements of the first thermoelectric unit is greater than a packing fraction of all thermoelements of the second thermoelectric unit. 
     
     
         92 . The device of  claim 50  wherein a combined thermal conduction channel area of all thermoelements of the first thermoelectric unit is different than a combined thermal conduction channel area of all thermoelements of the second thermoelectric unit. 
     
     
         93 . The device of  claim 50  wherein a combined thermal conduction channel area of all thermoelements of the first thermoelectric unit is greater than a combined thermal conduction channel area of all thermoelements of the second thermoelectric unit.