Fabrication of solar cells with electrically conductive polyimide adhesive
View Patent ↗The present disclosure provides a method of manufacturing a solar cell comprising: providing a semiconductor growth substrate; depositing on said growth substrate a sequence of layers of semiconductor material forming a solar cell; applying a metal contact layer over said sequence of layers; and affixing the surface of a permanent supporting substrate composed of a carbon fiber reinforced polymer utilizing a conductive polyimide binding resin directly over said metal contact layer and permanently bonding it thereto by a thermocompressive technique.
1. A method of manufacturing a solar cell comprising:
providing a semiconductor growth substrate;
depositing on said growth substrate a sequence of layers of semiconductor material forming a solar cell, wherein said step of depositing the sequence of layers of semiconductor material includes forming a first solar subcell on said substrate having a first band gap; forming a second solar subcell over said first subcell having a second band gap smaller than said first band gap; forming a grading interlayer over said second solar subcell having a third band gap larger than said second band gap; and forming a third solar subcell having a fourth band gap smaller than said second band gap such that said third subcell is lattice mismatched with respect to said second subcell;
applying a metal contact layer over said sequence of layers; and
affixing the surface of a permanent supporting substrate composed of a carbon fiber reinforced polymer utilizing a conductive polyimide binding resin directly over said metal contact layer and permanently bonding it thereto by a thermocompressive technique.
2. A method as defined in claim 1 , further comprising removing the semiconductor growth substrate subsequent to affixing the surface of a permanent supporting substrate directly over said metal contact layer and permanently bonding thereto.
3. A method as defined in claim 2 , wherein the semiconductor substrate is removed after the permanent supporting substrate has been attached by grinding, etching, or epitaxial lift-off.
4. A method as defined in claim 1 , further comprising forming grid electrodes on the surface of the layers of semiconductor material to form a top surface of the solar cell.
5. A method as defined in claim 4 , further comprising attaching a cover glass to the top surface of the solar cell.
6. A method as defined in claim 1 , wherein said growth substrate is composed of GaAs.
7. A method as defined in claim 1 , wherein said first solar subcell is composed of an InGa(Al)P emitter region and an InGa(Al)P base region.
8. A method as defined in claim 1 , wherein said grading interlayer is composed of (In x Ga 1-x ) y Al 1-y As, wherein 0<x<1 and 0<y<1 with x and y selected such that the band gap of each interlayer remains constant throughout its thickness.
9. A method as defined in claim 1 , wherein said first solar subcell is composed of an GaInP, GaAs, GaInAs, GaAsSb, or GaInAsN emitter region and an GaAs, GaInAs, GaAsSb, or GaInAsN base region, and the second solar subcell is composed of an InGaP emitter layer and a GaAs or GaInAs base layer.
10. The method as defined in claim 1 , wherein the first solar subcell is composed of an InGaAs base and emitter layer, or an InGaAs base layer and an InGaP emitter layer.
11. The method as defined in claim 1 , wherein the grading interlayer is compositionally graded to lattice match the second solar subcell on one side and the first solar subcell on the other side, and is composed of (In x Ga 1-x ) y Al 1-y As, wherein 0<x<1 and 0<y<1 with x and y selected such that the band gap of the interlayer remains constant throughout its thickness and greater than said second band gap.
12. A method as defined in claim 1 , wherein the step of affixing the conductive polyimide binding resin to the permanent supporting substrate is performed at a curing temperature above 350 degrees C.
13. A method of manufacturing a solar cell comprising:
providing a semiconductor growth substrate;
depositing on said growth substrate a sequence of layers of semiconductor material forming an inverted metamorphic multijunction solar cell, wherein said step of depositing the sequence of layers of semiconductor material includes forming a first solar subcell on said substrate having a first band gap; forming a second solar subcell over said first subcell having a second band gap smaller than said first band gap; forming a grading interlayer over said second solar subcell having a third band gap larger than said second band gap; and forming a third solar subcell having a fourth band gap smaller than said second band gap such that said third subcell is lattice mismatched with respect to said second subcell;
applying a metal contact layer over said sequence of layers;
affixing the surface of a permanent supporting substrate composed of a carbon fiber reinforced polymer utilizing a conductive polyimide binding resin directly over said metal contact layer and permanently bonding it thereto by a thermocompressive technique using a press for directing pressure and heat; and
removing the semiconductor growth substrate.
14. A method as defined in claim 13 , further comprising attaching a cover glass to the top surface of the solar cell.
15. A method as defined in claim 13 , wherein the step of affixing the conductive polyimide binding resin to the permanent supporting substrate is performed at a curing temperature above 350 degrees C.
16. A method as defined in claim 13 , wherein the growth substrate is removed after the permanent supporting substrate has been attached by grinding, etching, or epitaxial lift-off.
17. A method as defined in claim 13 , further comprising forming grid electrodes on the surface of the layers of semiconductor material to form a top surface of the solar cell.
18. A method as defined in claim 13 , wherein said growth substrate is composed of GaAs.