a) E gap was determined from the intersection of the EQE edge and the local EQE maximum; b) V oc was calculated from the measured J-V curves; c) V oc rad was calculated from FTPS and EL measurements; d) EQE EL is the EL quantum efficiency of the fabricated devices; e) Exp. ΔE 3 is calculated with the Equation (ΔE 3 = −kTln(EQE EL )).

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efficiencies (PCEs) of the state-of-theart all-PSCs have reached over 16-18% currently, [2] mainly resulting from the recent development of the polymerized small molecule acceptors (PSMAs). [1e,2b,eg] Nonetheless, the PCE of the all-PSCs still lags behind that (over 19%) of the SMA-based PSCs, [3] because of the lack of narrower bandgap P A s and the relative difficulty in finely tuning blend morphology of all-polymer systems. [1e,4] Encouraged by the development of the A-DA′D-A structured Y-series SMAs, [3a,5] several research groups reported narrow bandgap n-type PSMAs based on Y-series derivatives and increased PCEs of the all-PSCs to ≈13−17%. [2e,6] For instance, Jia et al. and Wang et al. first designed and synthesized Y5-based PSMAs PJ1 and PYT with thiophene as π-bridge, which achieved high PCEs of 14.4% and 13.4% by using polymer donors PBDB-T and PM6 in 2020. [6a,7] However, these Y5-based PSMAs as well as their derivatives are generally limited by their optical bandgaps (E opt g , E opt g values of 1.43-1.45 eV from the onset of the absorption profiles), [6b,7,8] leading to the limited photocurrent and efficiency improvement. Subsequently, Yu et al. and our group synthesized PSMAs PYF-T-o [9] and PY2F-T [2f ] containing a Y5 framework modified by fluorine atoms, which exhibited the narrower E opt g values of ≈1.38 eV and higher PCEs of over 15% achieved in relevant all-PSCs. In addition, Fu et al. and our group used benzotriazole as the central core to develop PSMAs PZT-γ [10] and PYT-Tz, [11] which possess red-shifted absorption and upshifted energy levels in comparison to PYT, thereby enhancing the short-circuit current density (J SC ) and PCE of the device. Subsequently, Fu and his coworkers further developed PSMAs with a selenophene-fused Y5 framework and halogenated end groups. [2g,12] Selenium and fluorine/chlorine substitutions have synergistic effects in broadening absorption and enhancing intermolecular interactions, resulting in red-shifted absorption (E opt g values of 1.37-1.40 eV) compared to other Y5-based PSMAs and better active layer morphology when blended with PM6. [2g,12b] Besides, in comparison to the thiophene linkerbased P A s PJ1 and PYT, the vinylene-based PSMA PY-V-γ demonstrates a slightly narrower E opt g of 1.41 eV and a better conjugation and tighter interchain stacking, resulting in more suitable phase segregation in the PY-V-γ blend with an improved PCE of 17.1%. [13] Therefore, developing high-performance P A s Achieving a finely tuned active layer morphology with a suitable vertical phase to facilitate both charge generation and charge transport has long been the main goal for pursuing the highly efficient bulk heterojunction all-polymer solar cells (all-PSCs). Herein, a solution to address the above challenge via synergistically combining the ternary blend strategy and the layer-by-layer (LbL) procedure is proposed. By introducing a synthesized polymer acceptor (P A ), PY-Cl, with higher crystallinity into the designed host acceptor PY-SSe-V, vertical phase...

Batch-to-batch variation widely exists in conjugated donor-acceptor (D-A) block copolymer materials and plays a crucial role in photovoltaic performance of organic solar cells (OSCs). To investigate the influence of conjugated-length of the intermediate block on the performance of singlecomponent OSC (SCOSCs), herein, four batches of conjugated block copolymers (CBCs, PB-b-PY-1, PB-b-PY-2, PB-b-PY-3, and PB-b-PY-4) are synthesized, which possess different D/A block lengths. As the conjugation length of intermediate D-block increases, the lamellar packing order of these CBCs shows a monotonically increasing trend, leading to stronger absorption spectra in the visible region, efficient charge transfer, and suppressed carrier recombination loss. Consequently, the PB-b-PY-4 device yields a higher efficiency of 13.28% than those of other CBCs. This study demonstrates the effectiveness of the conjugated length of intermediate D-blocks in designing high-performance conjugated D-A block copolymers, which paves the way toward developing high-performance SCOSCs.