Conductive pastes for forming solar cell electrodes

Abstract

The invention relates to a process for manufacturing solar cells. The manufacturing process of the invention comprises the steps of printing a conductive paste onto an n-type silicon layer of a crystalline silicon substrate or onto an antireflection film on the n-type silicon layer, and drying and firing the conductive paste to form an electrode. The conductive paste comprises a conductive powder, a glass frit and an organic vehicle. The glass frit comprises at least one oxide. X-ray photoelectron spectroscopy of the glass fit gives a spectrum representing binding energies of oxygen in which the signal intensity of a peak with a peak top at a range from 529 eV to less than 531 eV has a proportion of 40% or more relative to the total of signal intensities from 526 eV to 536 eV.

1 . A process for manufacturing solar cells comprising the steps of printing a conductive paste onto an n-type silicon layer of a crystalline silicon substrate or onto an antireflection film on the n-type silicon layer, and drying and firing the conductive paste to form an electrode,
 the conductive paste comprising a conductive powder, a glass frit and an organic vehicle,   the glass fit comprising at least one oxide,   X-ray photoelectron spectroscopy of the glass frit giving a spectrum representing binding energies of oxygen in which the signal intensity of a peak with a peak top at a range from 529 eV to less than 531 eV has a proportion of 40% or more relative to the total of signal intensities from 526 eV to 536 eV.   
     
     
         2 . The process for manufacturing solar cells according to  claim 1 , wherein the oxide comprised in the glass frit comprises silicon dioxide. 
     
     
         3 . The process for manufacturing solar cells according to  claim 1 , wherein the oxide comprised in the glass fit comprises at least one selected from lead oxide and boron oxide. 
     
     
         4 . The process for manufacturing solar cells according to  claim 1 , wherein the content of the glass frit is 1.5 to 10 parts by weight with respect to 100 parts by weight of the conductive powder. 
     
     
         5 . The process for manufacturing solar cells according to  claim 1 , wherein the conductive powder is a silver powder. 
     
     
         6 . The process for manufacturing solar cells according to  claim 1 , further comprising a step of forming an n-type silicon layer on a surface of a p-type crystalline silicon substrate, and optionally
 a step of forming an antireflection film on the n-type silicon layer.   
     
     
         7 . The process for manufacturing solar cells according to  claim 1 , wherein the electrode is a front electrode on the light incident side. 
     
     
         8 . A solar cell manufactured by the process described in  claim 1 . 
     
     
         9 . A conductive paste for forming solar cell electrodes comprising a conductive powder, a glass frit and an organic vehicle,
 the glass fit comprising at least one oxide,   X-ray photoelectron spectroscopy of the glass fit giving a spectrum representing binding energies of oxygen in which the signal intensity of a peak with a peak top at a range from 529 eV to less than 531 eV has a proportion of 40% or more relative to the total of signal intensities from 526 eV to 536 eV.   
     
     
         10 . The conductive paste according to  claim 9 , wherein the oxide comprised in the glass frit comprises silicon dioxide. 
     
     
         11 . The conductive paste according to  claim 9 , wherein the oxide comprised in the glass frit comprises at least one selected from lead oxide and boron oxide. 
     
     
         12 . The conductive paste according to  claim 9 , wherein the content of the glass fit is 1.5 to 10 parts by weight with respect to 100 parts by weight of the conductive powder. 
     
     
         13 . The conductive paste according to  claim 9 , wherein the conductive powder is a silver powder. 
     
     
         14 . A process for producing conductive pastes for forming solar cell electrodes, comprising:
 a step of measuring binding energies of oxygen in a glass fit by X-ray photoelectron spectroscopy,   a step of selecting a glass frit giving an X-ray photoelectron spectrum representing binding energies of oxygen in which the signal intensity of a peak with a peak top at a range from 529 eV to less than 531 eV has a proportion of 40% or more relative to the total of signal intensities from 526 eV to 536 eV, and   a step of mixing a conductive powder, the glass frit and an organic vehicle together.   
     
     
         15 . The process according to  claim 14 , wherein an oxide comprised in the glass fit comprises silicon dioxide. 
     
     
         16 . The process according to  claim 14 , wherein an oxide comprised in the glass frit comprises at least one selected from lead oxide and boron oxide. 
     
     
         17 . The process according to  claim 14 , wherein the content of the glass fit is 1.5 to 10 parts by weight with respect to 100 parts by weight of the conductive powder. 
     
     
         18 . The process according to  claim 14 , wherein the conductive powder is a silver powder.