Improving the Performance of Layer-by-Layer Organic Solar Cells by n-Doping of the Acceptor Layer

Abstract

Molecular dopants can effectively improve the performance of organic solar cells (OSCs). Here, PM6/BTP-eC9-4Cl-based OSCs are fabricated by a layer-by-layer (LbL) deposition method, and the electron acceptor BTP-eC9-4Cl layer is properly doped by n-type dopant benzyl viologen (BV) or [4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl]dimethyl-amine (N-DMBI-H). The power conversion efficiency (PCE) of OSCs increases from 16.80 to 17.61 or 17.84% when the acceptor layer is doped by BV (0.01 wt %) or N-DMBI-H (0.01 wt %), respectively. At the optimal doping concentration, the device exhibits more balanced charge transport, fewer bimolecular recombinations, faster charge separation and transfer, and better stability. This doping strategy has good universality; when the acceptor layer L8-BO of LbL OSCs is doped by 0.01 wt % BV or 0.01 wt % N-DMBI-H, the PCE increases from 17.49 to 18.35 or 18.25%, respectively. All in all, our studies have demonstrated that the doping strategy is effective in enhancing the performance of OSCs.

Effective N‐Doping of Non‐Fullerene Acceptor via Sequential Deposition Enables High‐Efficiency Organic Solar Cells

“…[ 27–29 ] Partly as a result, there are few reports on the successful use of n‐type dopants to build highly efficient SD OSCs (PCE > 18.5%). [ 15,30 ] Notably, due to the poor solubility of donor D18 in chloroform, [ 31,32 ] the SD device could be fabricated by quasi‐orthogonal solvents (chlorobenzene and chloroform), forming a quasiplanar heterojunction (Q‐PHJ) structure with favorable vertical component distribution, which provides efficient charge transport pathways. [ 33,34 ] Therefore, it is expected that achieving effective molecular doping in the active layers with optimal vertical morphology can promote charge transport and collection, resulting in superior short‐circuit current density ( J SC ) and fill factor (FF) in OSCs.…”