Highly efficient and flexible inverted polymer solar cell using PFN/AgNWs

Abstract

We report on highly efficient flexible inverted organic polymer solar cells (IPSCs) fabricated by low-temperature solution process on polyethylene terephalate (PET) substrate. In general, IPSCs have been required use an annealed (>200 oC) zinc oxide (ZnO) as an electron transport layer. However, any twisting of the flexible substrate during heat treatment leads to poor device performance. To overcome this issue, we developed a novel low temperatyre process for flexible IPSCs using an alcohol-/water-soluble conjugated polymer, namely poly [(9,9-bis(3'-(N,N-dimethylamino) propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) instead of the ZnO. Using this low-temperature process, we successfully demonstrate highly efficient flexible IPSCs that are proven to be capable of the power conversion efficiency (PCE) of 6.17 % which retain 96 % of its efficiency at a bending radius of R = 5 mm or less.