Semiconductor grain microstructures for photovoltaic cells

Abstract

Photovoltaic structures for the conversion of solar irradiance into electrical free energy. In particular implementations, the novel photovoltaic structures can be fabricated using low cost and scalable processes, such as magnetron sputtering. In a particular implementation, a photovoltaic cell includes a photoactive conversion layer comprising one or more granular semiconductor and oxide layers with nanometer-size semiconductor grains surrounded by a matrix of oxide. The semiconductor and oxide layer can be a disposed between electrode layers. In some implementations, multiple semiconductor and oxide layers can be deposited. These so-called semiconductor and oxide layers absorb sun light and convert solar irradiance into electrical free energy.

What is claimed is: 
     
         1 . A photovoltaic cell, comprising
 a first layer comprising an electron conducting material;   a second layer comprising a hole conducting material; and   wherein at least one of the first and second layers comprises a plurality of absorber semiconductor grains and an oxide material dispersed at boundaries of the absorber semiconductor grains.   
     
     
         2 . The photovoltaic cell of  claim 1  further comprising a one or more additional semiconductor and oxide layers, disposed between the first layer and the second layer, each comprising semiconductor material and an oxide material, wherein the oxide material is dispersed at grain boundaries of the semiconductor material. 
     
     
         3 . The photovoltaic cell of  claim 2  wherein at least one of the semiconductor and oxide layers is separated from an adjacent semiconductor and oxide layer with an intervening oxide layer. 
     
     
         4 . A photovoltaic cell, comprising
 an interlayer;   a semiconductor and oxide layer comprising an oxide and an n-type semiconductor, wherein the oxide is dispersed at grain boundaries of the n-type semiconductor; and   a hole conducting material layer.   
     
     
         5 . The photovoltaic cell of  claim 4  wherein the interlayer comprises a metal. 
     
     
         6 . The photovoltaic cell of  claim 4  wherein the hole conducting material layer comprises a p-type semiconductor. 
     
     
         7 . The photovoltaic cell of  claim 4  further comprising a seed layer, wherein the interlayer is deposited on the seed layer. 
     
     
         8 . The photovoltaic cell of  claim 4  further comprising a transparent conductive layer formed on the hole conducting material layer. 
     
     
         9 . The photovoltaic cell of  claim 8  further comprising a transparent protective layer formed over the transparent conductive layer. 
     
     
         10 . The photovoltaic cell of  claim 4  further comprising a metal and oxide layer, disposed between the interlayer and the semiconductor and oxide layer, comprising an oxide and a metal, wherein the oxide is dispersed at grain boundaries of the metal. 
     
     
         11 . The photovoltaic cell of  claim 4  further comprising a second semiconductor and oxide layer, disposed between the semiconductor and oxide layer and the hole conducting material layer, comprising an intrinsic semiconductor and an oxide, wherein the oxide is dispersed at grain boundaries of the intrinsic semiconductor. 
     
     
         12 . The photovoltaic cell of  claim 11  wherein at least one of the semiconductor and oxide layers is separated from an adjacent semiconductor and oxide layer with an intervening oxide layer. 
     
     
         13 . The photovoltaic cell of  claim 11  further comprising a third semiconductor and oxide layer, disposed between the second semiconductor and oxide layer and the hole conducting material layer, comprising an oxide and a p-type semiconductor, wherein the oxide is dispersed at grain boundaries of the p-type semiconductor. 
     
     
         14 . The photovoltaic cell of  claim 4  further comprising a semiconductor and oxide layer, disposed between the semiconductor and oxide layer and the hole conducting material layer, comprising an oxide and a p-type semiconductor, wherein the oxide is dispersed at grain boundaries of the p-type semiconductor. 
     
     
         15 . The photovoltaic cell of  claim 4  further comprising a metal and oxide layer, disposed between the semiconductor and oxide layer and the hole conducting material layer, comprising an oxide and a metal, wherein the oxide is dispersed at grain boundaries of the metal. 
     
     
         16 . The photovoltaic cell of  claim 4  further comprising
 a second semiconductor and oxide layer, disposed between the semiconductor and oxide layer and the hole conducting material layer, comprising an oxide and an p-type semiconductor, wherein the oxide is dispersed at grain boundaries of the p-type semiconductor, and 
 a metal and oxide layer, disposed between the semiconductor and oxide layer and the second semiconductor and oxide layer, comprising an oxide and a metal, wherein the oxide is dispersed at grain boundaries of the metal. 
 
     
     
         17 . A photovoltaic cell, comprising
 a interlayer;   a semiconductor and oxide layer comprising an oxide and an p-type semiconductor, wherein the oxide is dispersed at grain boundaries of the p-type semiconductor, and   an electron conducting material layer.   
     
     
         18 . The photovoltaic cell of  claim 17  wherein the electron conducting material layer comprises an n-type semiconductor. 
     
     
         19 . The photovoltaic cell of  claim 17  further comprising a seed layer, wherein the interlayer is deposited on the seed layer. 
     
     
         20 . The photovoltaic cell of  claim 17  further comprising a transparent conductive layer formed on the electron conducting material layer.