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.

Using a combinatory blending strategy is demonstrated as a promising path for designing efficient organic solar cells (OSCs) by boosting the short‐circuit current density and fill factor. Herein, a high‐performance ternary all‐small molecule OSC (all‐SMOSCs) using a narrow‐bandgap alloy acceptor containing symmetric and asymmetric molecules (BTP‐eC9 and SSe‐NIC) and a wide‐bandgap small molecule donor MPhS‐C2 is reported. Introducing the synthesized SSe‐NIC into the MPhS‐C2:BTP‐eC9 host system can broaden the absorption spectrum, modulate energy offsets, and optimize the molecular packing of the host materials. After systematically optimizing the weight ratio of MPhS‐C2:BTP‐eC9:SSe‐NIC, a champion efficiency of 18.02% is achieved. Impressively, the ternary system not only delivered a broad composition tolerance with device efficiencies over 17% throughout the whole blend ratios, but also exhibited less non‐geminate recombination and energy loss, and better‐light‐soaking stability than the corresponding binary systems. This work promotes the development of high‐performance ternary all‐SMOSCs and heralds their brighter application prospects.

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