Layer‐by‐Layer All‐Polymer Solar Cells Approaching 19% with Dual‐Donor Modulation of an Interpenetrating Network

AbstractAll‐polymer systems are promising for commercial applications because the lower diffusivity of polymers helps to inhibit the large‐scaled phase separation and obtain excellent stability. Achieving a fine‐tuned morphology of the active layer with an appropriate vertical phase has long been a major goal in obtaining efficient all‐polymer solar cells (all‐PSCs). Herein, through the synergistic effect of layer‐by‐layer (LBL) structure and dual donor strategy, high performance and stable all‐PSCs are prepared by constructing an interpenetrating network. The introduction of the third component PTzBI‐dF suppresses excessive aggregation and reduces exciton recombination. The formation of a favorable p‐i‐n structure helps to adjust the vertical phase distribution and improve stability. Ultimately, through the fine optimization, PBQx‐T‐Cl:PTzBI‐dF/PY‐IT achieves a high PCE of 18.83%. This research demonstrates a simple and effective way to construct high‐performance OSCs by desirable active layer morphology and vertical phase distribution.