# US 10,121,916 B2 · Solar cell > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,121,916 B2 - Document ID: US10121916B2 - Status: Granted - Kind: B2 - Application number: 15/025,491 - Filed: 2014-09-23 - Published: 2016-08-18 - Granted: 2018-11-06 - Earliest claimed: 2013-09-27 - Assignees: LG Innotek Co., Ltd. - Applicants: LG Innotek Co., Ltd. - Inventors: Myung Seok Shim - Web page: https://patentgrep.com/patent/US10121916B2 ## CPC - H10F 77/219: {Arrangements for electrodes of back-contact photovoltaic cells} - H10F 10/167: comprising Group I-III-VI materials, e.g. CdS/CuInSe2 [CIS] heterojunction photovoltaic cells - H10F 19/31: having multiple laterally adjacent thin-film photovoltaic cells deposited on the same substrate - H10F 77/1694: {the films including Group I-III-VI materials, e.g. CIS or CIGS} - H10F 77/211: {for photovoltaic cells} - H10F 77/70: Surface textures, e.g. pyramid structures - H10F 77/707: {of the substrates or of layers on substrates, e.g. textured ITO layer on a glass substrate} - Y02E 10/541: CuInSe2 material 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 A solar cell according to an embodiment comprises: a support substrate; a rear electrode layer formed on the support substrate; a first through groove formed on the rear electrode layer; an optical absorption layer formed on the rear electrode layer; and a front electrode layer formed on the optical absorption layer, wherein the average surface roughness (Ra1) of the support substrate, which is exposed by the first through groove, is in a range of 28 nm to 100 nm. ## Claims ### Claim 1 A solar cell comprising: a support substrate; a rear electrode layer disposed directly on the support substrate; a first through groove on the rear electrode layer; an optical absorption layer on the rear electrode layer; and a front electrode layer on the optical absorption layer, wherein a surface of the support substrate is exposed by the first through groove and has an average surface roughness (Ra1) in a range of 28 nm to 100 nm, wherein a top surface of the rear electrode layer and a lateral side surface of the rear electrode layer each has a same average surface roughness (Ra2) in a range of 28 nm to 100 nm, the lateral side surface of the rear electrode layer is exposed by the first through groove; and wherein the surface of the support substrate exposed by the first through groove, the top surface of the rear electrode layer, and the lateral side surface of the rear electrode layer exposed by the first through groove each includes a concavo-convex pattern having a same shape, and wherein the average surface roughness (Ra1) of the surface of the support substrate exposed by the first through groove is greater than the average surface roughness (Ra2) of the top surface of the rear electrode layer and the lateral side surface of the rear electrode layer exposed by the first through groove. ### Claim 2 (depends on 1) The solar cell of claim 1, wherein the average surface roughness (Ra1) of the surface of the support substrate exposed by the first through groove is greater than the average surface roughness (Ra2) of the top surface of the rear electrode layer and the lateral side surface of the rear electrode layer exposed by the first through groove, by 1 nm to 10 nm. ### Claim 3 (depends on 1) The solar cell of claim 1, wherein the surface of the support substrate, the top surface of the rear electrode layer, or the lateral side surface of the rear electrode layer exposed by the first through groove is provided in at least one of a triangular shape, a rectangular shape, and a circular shape. ### Claim 4 (depends on 1) The solar cell of claim 1, wherein at least one of the surface of the support substrate exposed by the first through groove, the top surface of the rear electrode layer, and the lateral side surface of the rear electrode layer exposed by the first through groove contains sulfur (S) or fluorine (F). ### Claim 5 (depends on 1) The solar cell of claim 1, wherein the rear electrode layer is divided into a plurality of rear electrodes by the first through groove. ### Claim 6 (depends on 1) The solar cell of claim 1, wherein the optical absorption layer fills space of the first through groove. ### Claim 7 (depends on 1) The solar cell of claim 1, wherein the rear electrode layer includes molybdenum. ### Claim 8 A solar cell comprising: a support substrate; a rear electrode layer disposed directly on the support substrate; a first through groove on the rear electrode layer; an optical absorption layer on the rear electrode layer; and a front electrode layer on the optical absorption layer, wherein the rear electrode layer comprises: a first contact surface being where a top surface of the rear electrode layer makes contact with the optical absorption layer; and a second contact surface being where a lateral side surface of the rear electrode layer exposed by the first through groove makes contact with the optical absorption layer; wherein the support substrate comprises a third contact surface being where a top surface of the support substrate exposed by the first through groove makes contact with the optical absorption layer; wherein the first contact surface, the second contact surface, and the third contact surface each include a concavo-convex pattern having a same shape, wherein an average surface roughness of the first contact surface, an average surface roughness of the second contact surface, and an average surface roughness of the third contact surface are each in a range of 28 nm to 100 nm, and wherein the average surface roughness of the third contact surface is greater than the average surface roughness of the first contact surface and the average surface roughness of the second contact surface. ### Claim 9 (depends on 8) The solar cell of claim 8, wherein the first contact surface, the second contact surface, and the third contact surface are each provided in at least one of a triangular shape, a rectangular shape, and a circular shape. ### Claim 10 (depends on 8) The solar cell of claim 8, wherein the average surface roughness of the third contact surface is greater than the average surface roughness of the first contact surface and the average surface roughness of the second contact surface by 1 nm to 10 nm. ### Claim 11 (depends on 8) The solar cell of claim 8, wherein the first contact surface, the second contact surface, and the third contact surface contain sulfur (S) or fluorine (F). ### Claim 12 (depends on 8) The solar cell of claim 8, wherein the rear electrode layer is divided into a plurality of rear electrodes by the first through groove.