Photovoltaic Devices Including an Interfacial Layer

Abstract

A photovoltaic cell can include an interfacial layer in contact with a semiconductor layer.

1 . A photovoltaic device comprising:
 a transparent conductive layer on a substrate;   a first semiconductor layer including a wide bandgap semiconductor;   a second semiconductor layer having a surface; and   an interfacial layer in contact with the second semiconductor layer, wherein the interfacial layer maintains a chemical potential of the second semiconductor layer at a controlled level wherein the interfacial material includes GeTe, CdTe:P, CdTe:N, NiAs or NbP.   
     
     
         2 . The device of  claim 1  wherein the second semiconductor layer includes a CdTe. 
     
     
         3 . The device of  claim 1  wherein the second semiconductor layer includes an alloy of CdTe. 
     
     
         4 . The device of  claim 2  wherein the second semiconductor layer includes CdTe alloys wherein Cd is at least partially replaced by Zn, Hg, Mg or Mn. 
     
     
         5 . The device of  claim 1  wherein the second semiconductor layer includes CdTe alloys wherein Te is at least partially replaced by S, Se or O. 
     
     
         6 . The device of  claim 2  wherein the chemical potential is that of the CdTe. 
     
     
         7 . The device of  claim 1  wherein the chemical potential is controlled within a region of the semiconductor proximate to the interface of the second semiconductor. 
     
     
         8 . The device of  claim 1  wherein the interfacial layer is between the second semiconductor layer and a back electrode. 
     
     
         9 . The device of  claim 1  wherein the interfacial layer is a third semiconductor layer. 
     
     
         10 . The device of  claim 1  wherein the semiconductor material includes ZnTe, CdZnTe, CuAlS 2 , CuAlSe 2 , CuAlO 2 , CuGaO 2 , or CuInO 2 . 
     
     
         11 . The device of  claim 2  wherein the surface includes chemical bonds between Cd and an element from column VA of the periodic table. 
     
     
         12 . The device of  claim 1  wherein the interfacial layer is between the second semiconductor and the first semiconductor layer. 
     
     
         13 . The device of  claim 1  in which the first semiconductor layer is SnO 2 , SnO 2 :Zn, SnO 2 :Cd, ZnO, ZnSe, GaN, In 2 O 3 , CdSnO 3 , ZnS or CdZnS. 
     
     
         14 . The device of  claim 2  wherein the surface includes chemical bonds between Te and any of the elements from column IIIA of the periodic table. 
     
     
         15 . The device of  claim 1 , wherein the interfacial layer is a material with a chemical formula ABO 2 , wherein A is either Cu, Ag, Au, Pt or Pd and B is one of the trivalent metal ions Al, In, Cr, Co, Fe, Ga, Ti, Co, Ni, Cs, Rh, Sn, Y, La, Pr, Nd, Sm or Eu, or doped compositions thereof. 
     
     
         16 . The device of  claim 1  wherein second semiconductor layer is less than 2 um thick. 
     
     
         17 . The device of  claim 1  further comprising an additional interfacial layer between the transparent conductive layer and the first semiconductor layer. 
     
     
         18 . A method of manufacturing a photovoltaic device comprising:
 depositing a first semiconductor layer on a substrate, the first semiconductor layer including a wide bandgap semiconductor;   depositing a second semiconductor layer over the first semiconductor layer; and   depositing an interfacial layer to contact a second semiconductor layer, wherein the interfacial layer maintains the chemical potential of the second semiconductor layer at a controlled level.   
     
     
         19 . The method of  claim 18 , wherein the interfacial layer is deposited by sputtering, by atomic layer deposition, or by selective ion layer adsorption and reaction deposition. 
     
     
         20 . A system for generating electrical energy comprising:
 a transparent conductive layer on a substrate;   a first semiconductor layer including a wide bandgap semiconductor;   a second semiconductor layer;   an interfacial layer in contact with the second semiconductor layer, wherein the interfacial layer maintains a chemical potential of the second semiconductor layer at a controlled level;   a first electrical connection connected to the transparent conductive layer; and   a second electrical connection connected to the back metal contact.