# US 2014/0190550 A1 · Tandem solar cell with graphene interlayer and method of making > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0190550 A1 - Document ID: US20140190550A1 - Status: Published application - Kind: A1 - Application number: 14/238,305 - Filed: 2012-08-08 - Published: 2014-07-10 - Earliest claimed: 2011-08-11 - Assignees: National University of Singapore - Inventors: Kian Ping Loh; Shi Wun Tong; Yu Wang - Web page: https://patentgrep.com/patent/US20140190550A1 ## CPC - H10K 30/57: comprising multiple junctions, e.g. tandem PV cells - H10K 30/83: comprising arrangements for extracting the current from the cell, e.g. metal finger grid systems to reduce the serial resistance of transparent electrodes - H10K 30/211: {comprising multiple junctions, e.g. double heterojunctions} - H10K 30/81: Electrodes - Y02E 10/549: Organic PV cells - H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A tandem solar cell with graphene interlayer and method of making are disclosed. The graphene interlayer can serve as a recombination contact to a pair of photoactive subcells electrically connected in series or as a common electrode to a pair of photoactive subcells electrically connected in parallel. The highly conducting, transparent nature, and easily modifiable chemical and electrical properties of a graphene interlayer enable tunable energy matching to the photoactive subcells. Using different photoactive subcells that can harvest light across the solar spectrum results in a tandem solar cell that can achieve high power conversion efficiency. ## Claims ### Claim at position 1 -58. (canceled) ### Claim 59 A tandem organic photovoltaic cell, comprising: a first photoactive subcell; a second photoactive subcell; and an intermediate layer comprising graphene, disposed between the first photoactive subcell and the second photoactive subcell, that collects charges generated from the first photoactive subcell and the second photoactive subcell. ### Claim 60 (depends on 59) The tandem organic photovoltaic cell according to claim 59, wherein the first photoactive subcell and the second photoactive subcell are electrically coupled in series or in parallel. ### Claim 61 (depends on 59) The tandem organic photovoltaic cell according to claim 59, wherein the first photoactive subcell comprises a substrate, a first electrode disposed on the substrate, a first hole transporting layer disposed on the first electrode, a first photoactive layer disposed on the first hole transporting layer, a first electron transporting layer disposed on the first photoactive layer and a second electrode disposed over the first electron transporting layer. ### Claim 62 (depends on 61) The tandem organic photovoltaic cell according to claim 61, wherein the second photoactive subcell comprises a third electrode, a second hole transporting layer disposed on the third electrode, a second photoactive layer disposed on the second hole transporting layer, a second electron transporting layer disposed on the second photoactive layer and a fourth electrode disposed over the second electron transporting layer. ### Claim 63 (depends on 59) The tandem organic photovoltaic cell according to claim 59, wherein the first photoactive subcell comprises a substrate, a first electrode disposed on the substrate, a first electron transporting layer disposed on the first electrode, a first photoactive layer disposed on the first electron transporting layer, a first hole transporting layer disposed on the first photoactive layer and a second electrode disposed over the first hole transporting layer. ### Claim 64 (depends on 63) The tandem organic photovoltaic cell according to claim 63, wherein the second photoactive subcell comprises a third electrode, a second electron transporting layer disposed on the third electrode, a second photoactive layer disposed on the second electron transporting layer, a second hole transporting layer disposed on the second photoactive layer and a fourth electrode disposed over the second hole transporting layer. ### Claim 65 (depends on 64) The tandem organic photovoltaic cell according to claim 64, wherein the second electrode of the first photoactive subcell and the third electrode of the second photoactive subcell form a recombination contact zone that comprises the intermediate layer comprising graphene. ### Claim 66 (depends on 65) The tandem organic photovoltaic cell according to claim 65, wherein the recombination contact zone formed from the intermediate layer comprising graphene is configured to let both positive and negative charges recombine from the first photoactive subcell and the second photoactive subcell, and wherein the first electrode of the first photoactive subcell is configured as an electrical contact to collect holes or electrons while the fourth electrode of the second photoactive subcell is configured as an electrical contact to collect holes or electrons. ### Claim 67 (depends on 59) The tandem organic photovoltaic cell according to claim 59, wherein the first photoactive subcell comprises a substrate, a first electrode disposed on the substrate, a first hole transporting layer disposed on the first electrode, a first photoactive layer disposed on the first hole transporting layer, a first electron transporting layer disposed on the first photoactive layer and a second electrode disposed over the first electron transporting layer. ### Claim 68 (depends on 67) The tandem organic photovoltaic cell according to claim 67, wherein the second photoactive subcell comprises a third electrode, a second electron transporting layer disposed on the third electrode, a second photoactive layer disposed on the second electron transporting layer, a second hole transporting layer disposed on the second photoactive layer and a fourth electrode disposed over the second hole transporting layer. ### Claim 69 (depends on 68) The tandem organic photovoltaic cell according to claim 68, wherein the second electrode of the first photoactive subcell and the third electrode of the second photoactive subcell form a common electrode that comprises the intermediate layer comprising graphene. ### Claim 70 (depends on 69) The tandem organic photovoltaic cell according to claim 69, wherein the common electrode formed from the intermediate layer comprising graphene is configured to collect electrons generated from the first photoactive subcell and the second photoactive subcell, and wherein the first electrode of the first photoactive subcell and the fourth electrode of the second photoactive subcell are used as electrical contacts to collect holes generated from the first photoactive subcell and the second photoactive subcell. ### Claim 71 (depends on 70) The tandem organic photovoltaic cell according to claim 70, wherein the first electrode of the first photoactive subcell and the fourth electrode of the second photoactive subcell have an electrical connection. ### Claim 72 A tandem photovoltaic cell, comprising: two or more photoactive subcells; a graphene film layer disposed between each pair of photoactive subcells in the two or more photoactive subcells, the graphene film layer providing an electrical connection between each pair of photoactive subcells, wherein the graphene film layer provides a selective contact of a same polarity to each pair of photoactive subcells to collect charges generated therefrom. ### Claim 73 (depends on 72) The tandem photovoltaic cell according to claim 72, wherein each pair of photoactive subcells in the two or more photoactive subcells are electrically coupled in series or in parallel. ### Claim 74 (depends on 73) The tandem photovoltaic cell according to claim 73, wherein the graphene film layer forms a recombination contact zone that is configured to collect both positive and negative charges generated from each pair of photoactive subcells. ### Claim 75 (depends on 73) The tandem photovoltaic cell according to claim 73, wherein the graphene film layer forms a common electrode that is configured to collect holes generated from each pair of photoactive subcells, while electrodes associated with each pair of photoactive subcells that are outwardly disposed from the graphene film layer are used as electrical contacts to collect electrons generated from each pair of photoactive subcells. ### Claim 76 A method of preparing a graphene film layer for disposing between a first photoactive subcell and a second photoactive subcell, comprising: doping the graphene film layer with a conductivity-enhancing dopant. ### Claim 77 (depends on 76) The method according to claim 76, further comprising modifying the graphene film layer with a modifying layer including a PEDOT polymer and a transition metal oxide. ### Claim 78 The method of transferring a grown graphene film layer onto a targeted material, comprising: a dry transfer process based on a polydimethylsiloxane (PDMS) stamp and applying an etching process.