Abstract
The emergence of polymerized small molecule acceptors (PSMAs) has
significantly improved the performance of all-polymer solar cells
(all-PSCs). However, the pace of device engineering lacks behind that of
materials development, so that a majority of the PSMAs have not
fulfilled their potentials. Furthermore, most high-performance all-PSCs
rely on the use of chloroform as the processing solvent. For instance,
the recent high-performance PSMA named PJ1-γ , with high LUMO and
HOMO levels, could only achieve a PCE of 16.1% with a high-energy-level
donor (JD40) using chloroform. Herein, we present a methodology
combining sequential processing (SqP) with the addition of 0.5%wt
PC71BM as a solid additive (SA) to achieve an impressive
efficiency of 18.0% for all-PSCs processed from toluene, an aromatic
hydrocarbon solvent. Compared to the conventional blend-casting (BC)
method whose best efficiency (16.7%) could only be achieved using
chloroform, the SqP method significantly boosted the device efficiency
using toluene as the processing solvent. In addition, the donor we
employ is the classic PM6 that has deeper energy levels than JD40, which
provides low energy loss for the device. We compare the results with
another PSMA (PYF-T-o ) with the same method. Finally, an improved
photostability of the SqP devices with the incorporation of SA is
demonstrated.
Key words: all-polymers solar cells, sequential processing,
solid additive