Photovoltaic heterojunction structures
First Claim
1. An improved photovoltaic structure comprising:
- three layers of polycrystalline semiconductor materials for the production and collection of electronic charge carriers generated in response to the incidence of light on said layered structure, said layers being disposed in series optically and in sequential touching contact;
wherein each layer has a different composition so that a heterojunction is formed at each of the two junctions between said three layers, two of said layers are of a first conductivity type and are in touching contact at one of said heterojunctions, the third layer is of a conductivity type opposite said first conductivity type, at least two of said layers contain cadmium as a principal constituent, two of said layers contain tellurium as a principal constituent, and the central layer between the two other layers of said structure is selected from the group consisting of n-type cadmium telluride, p-type Cdx Hg1-x Te, p-type Cdx Zn1-x Te, and p-type Hgx Zn1-n Te , where x ranges from greater than zero to less than one.
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Abstract
A three layer, photovoltaic structure having polycrystalline semiconductor layers disposed in series optically and in sequential touching contact includes a relatively wide optical bandgap energy window layer, a light-absorbing layer and a third, relatively wide bandgap energy layer that forms a minority carrier mirror with the light-absorbing layer. All three layers have different compositions so that the structure includes two heterojunctions. The light-absorbing layer and third layer are of the same conductivity type. The structure is conveniently realized using II-VI semiconductor compounds such as a cadmium sulfide or zinc sulfide window layer, a mercury cadmium telluride, cadmium telluride, zinc cadmium telluride or mercury zinc telluride light-absorbing layer and a third layer of cadmium telluride, zinc telluride, zinc cadmium telluride, mercury cadmium telluride or cadmium manganese telluride. Cadmium is present in at least two of the three layers of the novel structures. Tellurium is present in two of the three layers. Structures according to the invention may be conveniently formed by electrodeposition and may employ opaque or transparent substrates depending on the particular semiconductor materials used and their relative positions.
41 Citations
11 Claims
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1. An improved photovoltaic structure comprising:
three layers of polycrystalline semiconductor materials for the production and collection of electronic charge carriers generated in response to the incidence of light on said layered structure, said layers being disposed in series optically and in sequential touching contact;
wherein each layer has a different composition so that a heterojunction is formed at each of the two junctions between said three layers, two of said layers are of a first conductivity type and are in touching contact at one of said heterojunctions, the third layer is of a conductivity type opposite said first conductivity type, at least two of said layers contain cadmium as a principal constituent, two of said layers contain tellurium as a principal constituent, and the central layer between the two other layers of said structure is selected from the group consisting of n-type cadmium telluride, p-type Cdx Hg1-x Te, p-type Cdx Zn1-x Te, and p-type Hgx Zn1-n Te , where x ranges from greater than zero to less than one.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An improved photovoltaic structure comprising:
three layers of polycrystalline semiconductor materials for the production and collection of electronic charge carriers generated in response to the incidence of light on said layered structure, said layers being disposed in series optically and in sequential touching contact, wherein each layer has a different composition so that a heterojunction is formed at each of the two junctions between the three layers, two of said layers are of a first conductivity type and are in touching contact at one of said heterojunctions, the third layer is of a conductivity type opposite the first conductivity type, and one of said three layers is n-type cadmium sulfide, the central layer in contact with the other two layers is cadium telluride and the other layer in contact with said central layer is p-type Cdz Zn1-z Te where z ranges from zero to less than one. - View Dependent Claims (10, 11)
Specification