# US 2014/0150849 A1 · Photovoltaic cell and method of production thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0150849 A1 - Document ID: US20140150849A1 - Status: Published application - Kind: A1 - Application number: 13/689,824 - Filed: 2012-11-30 - Published: 2014-06-05 - Earliest claimed: 2012-11-30 - Assignees: Deutsche Cell GmbH - Applicants: Deutsche Cell GmbH - Inventors: Frederick Bamberg - Web page: https://patentgrep.com/patent/US20140150849A1 ## CPC - H10F 19/00: Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules - H10F 10/14: Photovoltaic cells having only PN homojunction potential barriers - H10F 77/211: {for photovoltaic cells} - H10F 77/311: {for photovoltaic cells} - Y02E 10/547: Monocrystalline silicon PV cells - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract The present invention relates to a method of forming a metal layer on the surface of a photovoltaic cell by forming a first layer of a first composition on the surface of a silicon substrate and then forming a second layer of a second composition on the first layer, wherein both layers are in electrical contact with each other, the first composition comprises particles comprising or consisting of (i) B, Al, Ga, In, and/or Tl or (ii) P, As, Sb, and/or Bi, the second composition comprises metal particles, and wherein the particles of the first layer have a mean diameter smaller than the mean diameter of the metal particles of the second composition. Further, the present invention also relates to photovoltaic cells and solar modules obtainable using the method of the present invention. ## Claims ### Claim 1 A method of forming a layer on the surface of a silicon substrate, the method comprising: (i) forming a first layer of a first composition on the surface of the silicon substrate; and (ii) forming a second layer of a second composition on the first layer; wherein both layers are in electrical contact with each other, the first composition comprises particles comprising or consisting of (i) B, Al, Ga, and/or Tl or (ii) P, As, Sb, and/or Bi, the second composition comprises particles comprising or consisting of a metal, and wherein the particles of the first layer have a mean diameter smaller than the mean diameter of the metal particles of the second composition. ### Claim 2 (depends on 1) The method according to claim 1, wherein the first layer and/or the second layer are formed by screen printing, extrusion printing, and/or plating deposition the first composition and/or the second composition onto the silicon substrate. ### Claim 3 (depends on 1) The method according to claim 1, wherein the particles of the first composition comprise (i) B and/or Al or (ii) P and/or Sb; and/or wherein the particles of the second composition comprise an electrically conductive metal, preferably Al. ### Claim 4 (depends on 1) The method according to claim 1, wherein the particles of the first composition and/or the metal particles of the second composition are substantially monodisperse. ### Claim 5 (depends on 1) The method according to claim 1, wherein the mean thickness of the first layer is smaller than the mean thickness of the second layer. ### Claim 6 (depends on 1) The method according to claim 1, wherein the first composition and/or the second composition further comprise at least one component selected from the group consisting of solvents, dispersing agents, additives, rheology adjusting agents, fillers, glasses, and mixtures thereof. ### Claim 7 (depends on 1) The method according to claim 1, wherein the silicon substrate is a photovoltaic cell. ### Claim 8 (depends on 1) A photovoltaic cell obtainable according to the method of claim 1. ### Claim 9 Photovoltaic cell comprising a back surface metal layer, the back surface metal layer comprising a first layer and a second layer, the first layer comprising particles comprising or consisting of (i) B, Al, Ga, and/or Tl or (ii) P, As, Sb, and/or Bi, the second layer comprising metal particles, and the first layer being sandwiched between a silicon substrate of the photovoltaic cell and the second layer, wherein the first layer comprises particles with a smaller mean diameter than the metal particles of the second layer. ### Claim 10 (depends on 9) The photovoltaic cell according to claim 9, wherein the particles of the first layer and/or the metal particles of the second layer are substantially monodisperse. ### Claim 11 (depends on 9) The photovoltaic cell according to claim 9, wherein the mean thickness of the first layer is smaller than the mean thickness of the second layer. ### Claim 12 (depends on 9) The photovoltaic cell according to claim 9, wherein the thickness of the first layer is in the range of between about 0.1 μm-20 μm. ### Claim 13 (depends on 9) The photovoltaic cell according to claim 9, wherein the thickness of the second layer is in the range of between about 2 μm-70 μm. ### Claim 14 (depends on 9) The photovoltaic cell according to claim 9, wherein the particles of the first layer have a mean diameter of about 0.01 μm to about 5 μm. ### Claim 15 (depends on 9) The photovoltaic cell according to claim 9, wherein the metal particles of the second layer have a mean diameter of about 0.1 μm to about 20 μm. ### Claim 16 (depends on 9) A solar module comprising one or more photovoltaic cells according to claim 9. ### Claim 17 (depends on 9) The photovoltaic cell according to claim 9, wherein the thickness of the first layer is in the range of between about 0.5 μm-15 μm. ### Claim 18 (depends on 9) The photovoltaic cell according to claim 9, wherein the thickness of the first layer is in the range of between about 1 μm-10 μm. ### Claim 19 (depends on 9) The photovoltaic cell according to claim 9, wherein the thickness of the second layer is in the range of between about 3 μm-40 μm. ### Claim 20 (depends on 9) The photovoltaic cell according to claim 9, wherein the thickness of the second layer is in the range of between about 5 μm-30 μm.