Application of Electrical Conductors of a Solar Cell

A solar cell consisting of a substrate and an electrically conductive pattern comprising a pattern of electrical conductors including grid lines for collecting current generated by the solar cell, wherein the pattern of electrical conductors is applied to the substrate by a method comprising:

• a) providing a flexible membrane, wherein a first surface of the membrane has a pattern of grooves formed therein, the pattern corresponding at least partially to a desired pattern of electrical conductors to be applied to the substrate;
• b) loading into the grooves of the first surface of the membrane a composition that includes, as composition components, electrically conductive particles and an adhesive, said loading being performed in one or more filling cycle(s) such that on completion of loading the composition substantially fills the grooves, level with the first surface of the membrane, and parts of the first surface between the grooves are substantially devoid of the composition;
• c) contacting the membrane with the substrate, with the first surface of the membrane facing the substrate;
• d) applying pressure to the membrane to cause the composition loaded into the grooves in the first surface of the membrane to adhere to the substrate;
• e) separating the membrane from the substrate to transfer the composition from the grooves in the first surface of the membrane to the substrate;
• and
• f) applying sufficient energy to sinter the electrically conductive particles and to render electrically conductive the pattern of composition transferred to the substrate from the grooves.

A solar cell having an electrically conductive pattern comprising a pattern of electrical conductors applied on a light harvesting side of the solar cell, the electrical conductors including grid lines for collecting current generated by the solar cell, wherein at least part of the electrical conductors fulfils the following structural features:

• a) the electrical conductors have a cross-section profile with a base of a width WB contacting the light harvesting side of the solar cell, an orthogonal distance h between the base and a top point of the profile (also termed the height of the profile), and an aspect ratio ASP between the height of the profile and the base width (ASP=h/WB), wherein:
• i. WB is at most 50 μm,
• ii. h is at most 50 μm;
• and
• iii. ASP is at least 0.7:1 and at most 5:1;
• b) wherein when, for at least five grid lines, at least ten width measurements are made at spaced points along each grid line and a mean width value and a standard deviation is calculated for each grid line, the average of the standard deviations calculated for the at least five grid lines is no more than 5% of the average of the mean width values calculated for the at least five grid lines;
• c) wherein when, for at least five grid lines, at least ten height measurements are made at spaced points along each grid line and a mean height value and a standard deviation is calculated for each grid line, the average of the standard deviations calculated for the at least five grid lines is no more than 5% of the average of the mean height values calculated for the at least five grid lines;
• and
• d) the grid lines have a normalized contact resistance of at most 0.3 Ω.cm when a sheet resistance of the light harvesting side is at least 50 Ω/□ and at most 110 Ω/□ and when the grid lines have a width of at least 15 μm and a height of at least 8 μm, or the grid lines have a normalized contact resistance of at most 0.6 Ω.cm when a sheet resistance of the light harvesting side is at least 111 Ω/□ and at most 140 Ω/□, and when the grid lines have a width of at least 15 μm and a height of at least 8 μm.