# US 2019/0378951 A1 · Fabricating thin-film optoelectronic devices with modified surface > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0378951 A1 - Document ID: US20190378951A1 - Status: Published application - Kind: A1 - Application number: 16/547,443 - Filed: 2019-08-21 - Published: 2019-12-12 - Earliest claimed: 2014-05-23 - Assignees: Flisom AG - Applicants: Flisom AG - Inventors: Patrick REINHARD; Fabian PIANEZZI; Benjamin BISSIG; Stephan BUECHELER; Ayodhya Nath TIWARI - Web page: https://patentgrep.com/patent/US20190378951A1 ## CPC - H10F 71/128: {Annealing} - H10F 10/167: comprising Group I-III-VI materials, e.g. CdS/CuInSe2 [CIS] heterojunction photovoltaic cells - H10F 19/30: comprising thin-film photovoltaic cells - H10F 77/126: {comprising only Group I-III-VI chalcopyrite materials, e.g. CuInSe2, CuGaSe2 or CuInGaSe2 [CIGS]} - H10F 77/1265: {characterised by the dopants} - H10F 77/148: {Shapes of potential barriers} - H10F 77/1698: {the metallic or insulating substrates being flexible} - H10F 77/211: {for photovoltaic cells} - H10P 14/3241: {being conductive materials} - H10P 14/3436: {being chalcogenide semiconductor materials not being oxides, e.g. ternary compounds} - H10P 14/38: {characterised by treatments done after the formation of the materials} - Y02E 10/541: CuInSe2 material PV cells - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A method (200) for fabricating thin-film optoelectronic devices (100), the method comprising: providing a substrate (110), forming a back-contact layer (120); forming at least one absorber layer (130) made of an ABC chalcogenide material, adding at least one alkali metal (235), and forming at least one cavity (236, 610, 612, 613) at the surface of the absorber layer wherein forming of said at least one cavity is by dissolving away from said surface of the absorber layer at least one crystal aggregate comprising at least one alkali crystal comprising at least one alkali metal. The method (200) is advantageous for more environmentally-friendly production of photovoltaic devices (100) on flexible substrates with high photovoltaic conversion efficiency and faster production rate. ## Claims ### Claim 1 A thin-film optoelectronic device, comprising: a substrate; a back-contact layer; an absorber layer formed of an ABC chalcogenide material, wherein A represents one or more elements selected from a group consisting of copper (Cu) and silver (Ag), B represents one or more elements selected from a group consisting of indium (In), gallium (Ga), and aluminum (Al), and C represents one or more elements selected from a group consisting of sulfur (S), selenium (Se), and tellurium (Te); at least one alkali metal; and at least one cavity at a surface of the absorber layer formed by dissolving at least one crystal aggregate away from the surface of the absorber layer, wherein the at least one crystal aggregate comprises at least one alkali crystal comprising the at least one alkali metal. ### Claim 2 (depends on 1) The device of claim 1, wherein the at least one alkali metal comprises potassium (K). ### Claim 3 (depends on 1) The device of claim 1, wherein the at least one alkali crystal comprises a cubic crystal. ### Claim 4 (depends on 1) The device of claim 1, wherein the at least one alkali metal comprises potassium and wherein a curve for counts of potassium in the device's sputter profiling graph comprises an upper peak of potassium within a depth ranging from the surface of the absorber layer to about 0.5 μm into the absorber layer. ### Claim 5 (depends on 4) The device of claim 4, wherein the upper peak of potassium comprises a base having a width in a range from about 0.1 μm to about 0.5 μm. ### Claim 6 (depends on 4) The device of claim 4, wherein the upper peak of potassium has a height measured from the number of counts above its base that is in a range from about 0.2 to about 17 times the number of counts from the point of minimum number of counts in potassium of the absorber layer to the number of counts at the base of the upper peak of potassium. ### Claim 7 (depends on 1) The device of claim 1, wherein the at least one alkali metal comprises potassium, a curve for a copper to selenium content in the device's energy dispersive X-ray line scan graph comprises an extended region of low and about constant Cu/Se extending from the surface of the absorber layer into a portion of the depth of the absorber layer, and the extended region of low and about constant Cu/Se has a depth in the range from about 0.05 μm to about 0.5 μm. ### Claim 8 (depends on 1) The device of claim 1, wherein the at least one alkali metal comprises potassium, the device comprises +1/+2 elements, and the X-ray photoelectron spectrometry curve comprises a cadmium (Cd) 3d5/2 peak that is at least about 60% greater in height than for the curve of a device wherein the at least one alkali metal does not comprise potassium. ### Claim 9 (depends on 1) The device of claim 1, wherein the at least one cavity at the surface of the absorber layer comprises a plurality of cavities, the cavities covering a total relative projected area in a range from about 15% to about 80% of the surface of the absorber layer. ### Claim 10 (depends on 1) The device of claim 1, wherein the at least one cavity at the surface of the absorber layer comprises a plurality of cavities, the cavities having a mean cavity area in a range from about 0.1×10−15 m2 to about 0.8×10−15 m2. ### Claim 11 (depends on 1) The device of claim 1, wherein the at least one cavity comprises cadmium. ### Claim 12 (depends on 1) The device of claim 1, further comprising at least one front-contact layer. ### Claim 13 A thin-film optoelectronic device, comprising: a substrate; a back-contact layer; an absorber layer formed of an ABC chalcogenide material, wherein A represents one or more elements selected from a group consisting of copper (Cu) and silver (Ag), B represents one or more elements selected from a group consisting of indium (In), gallium (Ga), and aluminum (Al), and C represents one or more elements selected from a group consisting of sulfur (S), selenium (Se), and tellurium (Te); at least one alkali metal; and at least one cavity at a surface of the absorber layer formed by dissolving at least one crystal aggregate away from the surface of the absorber layer, wherein the at least one crystal aggregate comprises at least one alkali crystal comprising the at least one alkali metal, and the at least one cavity comprises cadmium (Cd). ### Claim 14 (depends on 13) The device of claim 13, wherein the at least one alkali metal comprises potassium, the device comprises +1/+2 elements, and the X-ray photoelectron spectrometry curve comprises a Cd 3d5/2 peak that is at least about 60% greater in height than for the curve of a device wherein the at least one alkali metal does not comprise potassium. ### Claim 15 (depends on 13) The device of claim 13, wherein the at least one cavity at the surface of the absorber layer comprises a plurality of cavities, the cavities covering a total relative projected area in a range from about 15% to about 80% of the surface of the absorber layer. ### Claim 16 (depends on 13) The device of claim 13, wherein the at least one cavity at the surface of the absorber layer comprises a plurality of cavities, the cavities having a mean cavity area in a range from about 0.1×10−15 m2 to about 0.8×10−15 m2. ### Claim 17 A thin-film optoelectronic device, comprising: a substrate; a back-contact layer; an absorber layer formed of an ABC chalcogenide material, wherein A represents one or more elements selected from a group consisting of copper (Cu) and silver (Ag), B represents one or more elements selected from a group consisting of indium (In), gallium (Ga), and aluminum (Al), and C represents one or more elements selected from a group consisting of sulfur (S), selenium (Se), and tellurium (Te); at least one alkali metal comprising potassium (K); and at least one cavity at a surface of the absorber layer formed by dissolving at least one crystal aggregate away from the surface of the absorber layer, wherein the at least one crystal aggregate comprises at least one alkali crystal comprising the at least one alkali metal. ### Claim 18 (depends on 17) The device of claim 17, wherein a curve for counts of potassium in the device's sputter profiling graph comprises an upper peak of potassium within a depth ranging from the surface of the absorber layer to about 0.5 μm into the absorber layer. ### Claim 19 (depends on 18) The device of claim 18, wherein the upper peak of potassium comprises a base having a width in a range from about 0.1 μm to about 0.5 μm. ### Claim 20 (depends on 18) The device of claim 18, wherein the upper peak of potassium has a height measured from the number of counts above its base that is in a range from about 0.2 to about 17 times the number of counts from the point of minimum number of counts in potassium of the absorber layer to the number of counts at the base of the upper peak of potassium.