Enhancing the reproducibility of large-area organic solar cells via double-cable conjugated polymers

Abstract

Flexibility and large-area feasibility are the key roadmaps for organic solar cells (OSCs) toward industrialization. However, the efficiency gap and low reproducibility between small-area and large-area devices have impeded their further development. Here, the origination of these issues is studied in detail and the different viscosities of the donor and acceptor are found as the key factor. Their distinct viscosities generate inhomogeneous thin films via solution process, resulting in significantly reduced efficiencies and deteriorated reproducibility. As an alternative, double-cable polymers are found to perfectly tackle these issues, since they can act as a single photoactive layer in OSCs. For example, when going from 0.04 cm2 to 1.0 cm2 devices, bulk-heterojunction OSCs exhibit decreaased averaged-efficiencies from 7.29% to 4.66% and increase standard deviations from 0.45 to 2.18, while double-cable polymer based single-component OSCs show the averaged-efficiencies from 9.56% to 8.49% and standard deviations from 0.18 to 0.57. In addition, it is found that 1-cm2 flexible single-component OSCs exhibit excellent mechanical and storage stability. All these results demonstrate that double-cable conjugated polymers as a single layer can alleviate the reproducibility gap within lab-to-manufacturing translation toward stable, large-area flexible OSCs.