Coating which is applied to a substrate, a solar cell, and method for applying the coating to the substrate

Abstract

The invention relates to a coating which has been applied to a substrate, comprising at least a first film and a second film which have been applied on top of each other and each comprise a transparent conducting oxide and an electron donor, wherein the second film comprises relatively at least 10 percent less electron donor than the first film. The invention also relates to a solar cell comprising a coating according to the invention. The invention further relates to a method for applying the coating according to the invention to a substrate, wherein at least a first and a second mixture which each comprise one or more precursors for a transparent conducting oxide and an electron donor are applied to the substrate, wherein the second mixture is composed such that relatively at least 10 percent less electron donor is incorporated in the film compared with the film deposited by the first mixture.

1 .- 24 . (canceled) 
   
   
       25 . A coating which has been applied to a substrate, comprising a film which comprises a transparent conducting oxide and an electron donor, wherein the film comprises tin oxide of which the two dominant crystalline orientations are the (211) and (110) orientations. 
   
   
       26 . A coating according to  claim 25 , wherein the average particle size of the crystals of the transparent conducting oxide is 50-500 nm. 
   
   
       27 . A coating according to  claim 25 , wherein the average particle size of the crystals of the transparent conducting oxide is 100-300 nm. 
   
   
       28 . A coating according to  claim 25 , comprising at least a first film and a second film which each comprise a transparent conducting oxide and an electron donor, wherein the second film comprises tin oxide of which the two dominant crystalline orientations are the (211) and (110) orientations. 
   
   
       29 . A coating according to  claim 28 , wherein the first film has been applied to the substrate. 
   
   
       30 . A coating according to  claim 28 , wherein the first and second films both comprise tin oxide. 
   
   
       31 . A coating according to  claim 28 , wherein the first film has a thickness of 50-500 nm. 
   
   
       32 . A coating according to  claim 28 , wherein the second film has a thickness of 300-900 nm. 
   
   
       33 . A coating according to  claim 25 , wherein the coating has a total thickness of 300-1000 nm. 
   
   
       34 . A coating according to  claim 25 , wherein the substrate is made of metal, ceramic or glass or of a material which comprises one or more polymers. 
   
   
       35 . A solar cell comprising a coating according to  claim 25 . 
   
   
       36 . A method for applying the coating according to  claim 28  to a substrate, wherein at least a first and a second mixture which each comprise one or more precursors for a transparent conducting oxide and an electron donor are applied to the substrate, wherein the second mixture is composed such that relatively at least 10 percent less electron donor is incorporated in the second film. 
   
   
       37 . A method according to  claim 36 , wherein the first mixture is applied to the substrate and the first film is formed, after which the second mixture is applied to the top side of the first film and the second film is formed.