Solar cell and method for manufacturing the same

Abstract

The present invention relates to a solar cell. The solar cell includes a substrate of a first conductive type, an emitter layer of a second conductive type opposite the first conductive type on the substrate, first and second anti-reflection layers that are sequentially positioned on the emitter layer, a first electrode electrically connected to the emitter layer, first to third passivation layers that are sequentially positioned on the substrate, each of the first to third passivation layers including a plurality of exposed portions, and a plurality of second electrodes electrically connected to portions of the substrate exposed by the plurality of exposed portions.

1 . A method of forming an electrode of a solar cell comprising:
 selectively forming a passivation layer exposing at least a portion of a substrate on a portion of the substrate including an emitter layer, the passivation layer including at least one layer;   forming a first electrode electrically connected to the emitter layer; and   forming a plurality of second electrodes on the exposed portion of the substrate to electrically connect the plurality of second electrodes to the substrate.   
   
   
       2 . The method of  claim 1 , wherein the passivation layer is formed on a surface of the substrate on which light is not incident. 
   
   
       3 . The method of  claim 1 , wherein the forming of the passivation layer comprises:
 positioning a mask including a plurality of openings and a plurality of blocking portions on the substrate; and   forming a layer on portions of the substrate facing the openings and forming a plurality of exposed portions of the substrate facing the blocking portions to form the passivation layer including the plurality of exposed portions,   wherein the plurality of second electrodes are electrically connected to the substrate through the plurality of posing portions.   
   
   
       4 . A solar cell comprising:
 a substrate of a first conductive type;   an emitter layer of a second conductive type opposite the first conductive type on the substrate;   first and second anti-reflection layers that are sequentially positioned on the emitter layer;   a first electrode electrically connected to the emitter layer;   first to third passivation layers that are sequentially positioned on the substrate, each of the first to third passivation layers including a plurality of exposed portions; and   a plurality of second electrodes electrically connected to portions of the substrate exposed by the plurality of exposed portions.   
   
   
       5 . The solar cell of  claim 4 , wherein the first anti-reflection layer is formed of silicon nitride (SiNx:H), and the second anti-reflection layer is formed of silicon oxynitride (SiOxNy). 
   
   
       6 . The solar cell of  claim 4 , wherein a refractive index of the first anti-reflection layer is greater than a refractive index of the second anti-reflection layer. 
   
   
       7 . The solar cell of  claim 6 , wherein the first anti-reflection layer has a refractive index of about 2.2 to 2.6, and the second anti-reflection layer has a refractive index of about 1.3 to 1.6. 
   
   
       8 . The solar cell of  claim 4 , wherein the first passivation layer is formed of silicon oxide (SiOx), the second passivation layer is formed of silicon nitride (SiNx:H), and the third passivation layer is formed of silicon oxynitride (SiOxNy). 
   
   
       9 . The solar cell of  claim 4 , wherein the first passivation layer has a maximum refractive index, and the third passivation layer has a minimum refractive index. 
   
   
       10 . The solar cell of  claim 4 , wherein a thickness of the first electrode is greater than a sum of thicknesses of the first and second anti-reflection layers. 
   
   
       11 . A method for manufacturing a solar cell comprising:
 forming an emitter layer of a second conductive type opposite a first conductive type on a substrate of the first conductive type;   sequentially positioning the substrate in a plurality of chambers to form an anti-reflection layer on the emitter layer and to form a passivation layer including at least one exposed portion on a rear surface of the substrate opposite an incident surface of the substrate;   coating a first paste on the anti-reflection layer to form a first electrode pattern;   coating a second paste on the passivation layer and on a portion of the substrate exposed by the exposed portion to form a second electrode conductive layer pattern; and   performing a thermal process on the substrate having the first electrode pattern and the second electrode conductive layer pattern to form a plurality of first electrodes electrically connected to the emitter layer and to form a second electrode conductive layer including at least one second electrode electrically connected to the substrate.   
   
   
       12 . The method of  claim 11 , wherein a number of chambers is equal to a sum of a number of layers constituting the anti-reflection layer and a number of layers constituting the passivation layer,
 wherein a different source gas is injected into each of the plurality of chambers.   
   
   
       13 . The method of  claim 12 , wherein the anti-reflection layer includes first and second anti-reflection layers each having a different refractive index. 
   
   
       14 . The method of  claim 13 , wherein the first anti-reflection layer is formed of silicon nitride (SiNx:H), and the second anti-reflection layer is formed of silicon oxynitride (SiOxNy). 
   
   
       15 . The method of  claim 12 , wherein the passivation layer includes first, second, and third passivation layers each having a different refractive index. 
   
   
       16 . The method of  claim 15 , wherein the first passivation layer positioned closest to the substrate has a maximum refractive index, and the third passivation layer positioned farthest away from the substrate has a minimum refractive index. 
   
   
       17 . The method of  claim 16 , wherein the first passivation layer is formed of silicon oxide (Sio X ), the second passivation layer is formed of silicon nitride (SiNx:H), and the third passivation layer is formed of silicon oxynitride (SiOxNy). 
   
   
       18 . The method of  claim 15 , wherein the forming of the anti-reflection layer and the passivation layer comprises independently performing a layer formation process in each of the plurality of chambers. 
   
   
       19 . The method of  claim 18 , wherein the forming of the anti-reflection layer and the passivation layer comprises positioning a mask including at least one opening and at least one blocking portion on the substrate and performing the layer formation process on the substrate using the mask to form the first, second, and third passivation layers, wherein the same mask is used to form the first, second, and third passivation layers. 
   
   
       20 . The method of  claim 19 , wherein the layer formation process uses a chemical vapor deposition (CVD) method.