Layer-by-layer polymer solar cells (LbL-PSCs) were prepared with PNTB6-Cl as the donor and Y6 as the acceptor by a sequential spin-coating method. Two solvent additives DPE and DFB were individually incorporated into PNTB6-Cl chlorobenzene solution and Y6 chloroform solution. A PCE of 17.53% was achieved for the optimal LbL-PSCs with two solvent additives, which is much larger than the PCE of 16.38% for the LbL-PSCs without solvent additives. Over 7% PCE enhancement can be realized by individually employing solvent additives in donor and acceptor layers, resulting from the simultaneously enhanced open circuit voltage (VOC) of 0.88 V, short circuit current density (JSC) of 26.63 mA cm-2and fill factor (FF) of 74.83%. The photogenerated exciton distribution, charge transport and collection in the LbL-PSCs can be optimized by employing different solvent additives in donor and acceptor solutions. Meanwhile, the efficient energy transfer from PNTB6-Cl to Y6 can provide an additional channel for improving the exciton utilization efficiency through exciton dissociation at PNTB6-Cl/Y6 interfaces. Meanwhile, the PCEs of LbL-PSCs are better than those of bulk heterojunction PSCs with the same materials and solvent additives, indicating the great potential of LbL-PSCs for commercial application.
ASJC Scopus subject areas
- Materials Chemistry