Ternary All‐Polymer Solar Cells with Efficiency up to 18.14% Employing a Two‐Step Sequential Deposition

Abstract

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...

Achieving 17.94% efficiency all-polymer solar cells by independently induced D/A orderly stacking

“…This result could be attributed to the excellent miscibility between PY-IT and PBB2-H, which was verified by the surface energy measurements, and permitted homogeneous molecular intermixing as a foundation for the molecular packing and vertical phase separation variations. 54 In addition, from the 2D-GIWAXS images of the PPHJ-based blend films (Fig. 5(c)), the (010) diffraction peak in the OOP direction and (100) diffraction peak in the IP direction of the PPHJ-based ternary blend film were significantly enhanced compared to that of the PPHJ-based binary blend film, indicating that the introduction of PBB2-H effectively enhanced the intermolecular π–π stacking, which is beneficial to the charge transfer in the ternary active layer.…”

Critical Role of Non-Halogenated Solvent Additives in Eco-Friendly and Efficient All-Polymer Solar Cells

“…When light enters the photovoltaic layer, photoenergy is converted into electricity by following four steps: (1) exciton generation, (2) exciton diffusion, (3) exciton dissociation and charge generation, and (4) charge transport and charge collection [ 4 , 5 ]. Although OSCs based on n -type small molecules have recently achieved high power conversion efficiencies (PCEs) above 18% [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ], all-polymer solar cells (APSCs) have also attracted considerable attention because of the advantages of n -type polymers. The light absorption region and frontier energy levels of n -type polymers can be easily tuned to achieve complementary light absorption and a high open-circuit voltage ( V oc ) when they are blended with an appropriate p -type polymer [ 17 , 18 ].…”

Layer‐by‐Layer‐Processed Ternary All‐Polymer Organic Solar Cells with 17.74% Efficiency Enabled by Introducing a Designed Narrow‐Bandgap Guest Polymer Acceptor

“…[18,19] Different from SMA-based OSCs, all-polymer solar cells (all-PSCs) generally consist of polymer acceptor (P A ) and polymer donor (P D ) materials, largely addressing the aforementioned stability drawbacks. [20,21] However, the reported PCEs of relevant all-PSCs still lag behind those of the SMA-based OSCs, [20,[22][23][24][25] mainly owing to the limitations of P A s with the A-DA'D-A structured Y-series as conjugated polymer backbone and the relative difficulty in controlling the blend morphology of the bulk heterojunction (BHJ) active layer. [6][7][8][9][10]26,27] Recently, many groups reported narrow bandgap polymerized small molecule acceptors (PSMAs) based on A-DA'D-A-structured Y5 derivatives as the conjugated main backbone, which delivered high PCEs of 14%-17% in relevant all-PSCs.…”

“…[ 18,19 ] Different from SMA‐based OSCs, all‐polymer solar cells (all‐PSCs) generally consist of polymer acceptor ( P A ) and polymer donor ( P D ) materials, largely addressing the aforementioned stability drawbacks. [ 20,21 ] However, the reported PCEs of relevant all‐PSCs still lag behind those of the SMA‐based OSCs, [ 20,22–25 ] mainly owing to the limitations of P A s with the A‐DA’D‐A structured Y‐series as conjugated polymer backbone and the relative difficulty in controlling the blend morphology of the bulk heterojunction (BHJ) active layer. [ 6–10,26,27 ]…”