Adding a Third Component with Reduced Miscibility and Higher LUMO Level Enables Efficient Ternary Organic Solar Cells

Ma, Ruijie; Liu, Tao; Luo, Zhenghui; Gao, Ke; Chen, Kai; Zhang, Guangye; Gao, Wei; Xiao, Yiqun; Lau, Tsz‐Ki; Fan, Qunping; Chen, Yuzhong; Kuen, Lik; Sun, Huiliang; Cai, Guilong; Yang, Yongzhen; Lu, Xinhui; Wang, Ergang; Yang, Chuluo; Jen, Alex K.‐Y.; Yan, He

doi:10.1021/acsenergylett.0c01364

Cited by 205 publications

(121 citation statements)

References 66 publications

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“…Comparing PM6: Y6 and PM6:Y6: ITIC‐Th blends, the increased acceptor domain size in the latter blend potentially favors electron transport, and can partially account for the increased electron mobilities from 3.96 × 10 −4 to 4.54 × 10 −4 cm 2 V −1 second −1 . Besides, it is understandable that PM6:Y6: IT‐4F exhibited the higher electron mobilities than the PM6: Y6 control, which is attributed to the increased CCL of oop π ‐ π peak and the decreased electron energy disorder 73‐75 . All the blend films exhibited reasonable phase segregation scales with acceptor domain size around 20 nm, except for the PM6: ITIC‐Th blend with an acceptor domain size of approximately 49.3 nm.…”

Section: Resultsmentioning

confidence: 95%

Reducing V_OC loss via structure compatible and high lowest unoccupied molecular orbital nonfullerene acceptors for over 17%‐efficiency ternary organic photovoltaics

Yan

Cai

et al. 2020

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The ternary strategy is effectual to attain high-performance organic photovoltaics (OPVs). Herein, device processing and performance of PM6:Y6:IT-4F OPVs is improved, and ITIC-Th with high-lying lowest unoccupied molecular orbital is incorporated into PM6: Y6 blend. The PM6:Y6: ITIC-Th device afforded an excellent PCE of 17.2%, surpassing PM6: Y6 device, and becoming one of the highest PCE. The resulting ITIC-Th-based ternary OSCs demonstrated low energy loss (E loss) of 0.53 to 0.54 eV, as compared to their binary counterparts with either high open-circuit voltage (V OC) but large E loss , or less E loss but low V OC. The incorporation of ITIC-Th and IT-4F balanced the charge mobilities, and thereby retained and improved fill factors. Increased crystalline coherence length and smaller d-spacing of π-π peaks are also observed in ternary blends, indicating enhanced crystallinity and thus improved active-layer morphology. These findings demonstrate the feasibility of exploring the exciting pool of nonfullerene acceptors to pursue new breakthroughs of OPVs.

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Section: Resultsmentioning

confidence: 95%

Reducing V_OC loss via structure compatible and high lowest unoccupied molecular orbital nonfullerene acceptors for over 17%‐efficiency ternary organic photovoltaics

Yan

Cai

et al. 2020

EcoMat

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“…According to the surface energy of neat films, the interfacial energy between two different materials in the blend films can be evaluated using the following equation. [ 58,59 ]

γ_{AB} = γ_{normalA} + γ_{normalB} - \frac{4 γ_{normalA}^{normald} γ_{normalB}^{normald}}{γ_{normalA}^{normald} + γ_{normalB}^{normald}} - \frac{4 γ_{normalA}^{normalp} γ_{normalB}^{normalp}}{γ_{normalA}^{normalp} + γ_{normalB}^{normalp}}

…”

Section: Resultsmentioning

confidence: 99%

Ternary Organic Photovoltaic Cells Exhibiting 17.59% Efficiency with Two Compatible Y6 Derivations as Acceptor

et al. 2021

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Efficient organic photovoltaic cells (OPVs) are fabricated using two structurally similar Y6 derivations (BTP‐BO‐4F and Y6‐1O) as acceptor and PM6 as donor. The two binary OPVs exhibit a high fill factor (FF) (>76%), the complementary short‐circuit‐current density (JSC) and open‐circuit voltage (VOC). The high FFs of binary OPVs indicate the good compatibility of corresponding materials to form efficient charge transport channels. A power conversion efficiency (PCE) of 17.59% is obtained from ternary OPVs with 15 wt% Y6‐1O in acceptors, benefiting from the simultaneously improved JSC of 26.13 mA cm−2, a VOC of 0.860 V, and an FF of 78.26%. The values of VOC of ternary OPVs can be gradually increased along with the incorporation of Y6‐1O, suggesting the preferred formation of an alloyed state between BTP‐BO‐4F and Y6‐1O due to their good compatibility. Meanwhile, the cascaded energy levels of BTP‐BO‐4F and Y6‐1O can form efficient electron transport channels in ternary active layers. The main contribution of Y6‐1O can be summarized as enhancing photon harvesting, optimizing phase separation, and adjusting molecular arrangement. The experimental results may provide new insight on developing efficient ternary OPVs by selecting two well‐compatible acceptors.

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“…[ 52 ] The miscibility between the donor and acceptor can be quantized by the Flory–Huggins interaction parameter χ D–A . [ 56,57 ] The larger χ D–A is, the worse the miscibility is, vise versa. To calculate χ D–A , we performed the contact angle tests on water and diiodomethane, and the results are shown in Figure .…”

Section: Figurementioning

confidence: 99%

Layer‐by‐Layer Processed Ternary Organic Photovoltaics with Efficiency over 18%

et al. 2021

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composed of both electron donor (D) and acceptor (A), finally, transformed to bulk-heterojunction (BHJ) cells formed between D and A, and BHJ structures were further optimized by introducing additional charge-transporting and/or interfacial layers. [27-29] The objectives of the above modifications in device structure are the same: charges can be generated and extracted more efficiently via appropriate spatial alignment of functional components. Currently, BHJ structure is still the dominant configuration for OPV devices, because it can create sufficient D/A interfaces for charge separation, but exist the risk of obvious charge recombination. [30-36] Since charges are transported and collected in vertical direction within OPV devices, forming a preferred vertical phase distribution to some extent, like donor-enrichment at the anode and acceptor-enrichment at the cathode, is a more ideal morphology to reduce the charge recombination and promote the charge collection efficiencies. [37-39] However, it's a tough task for BHJ structure to form well vertical phase distribution. Especially for non-fullerene acceptor-based OPVs, due to the high similarity in chemical structures between donors and nonfullerene acceptors, it will make thermodynamically D and A mix too well. [40] Therefore, it's a tough challenge for fullerenefree OPVs to realize the desirable vertical phase distribution. To achieve the vertical phase distribution, researchers have developed layer-by-layer (LbL) processing method by sequential depositing D and A layers, so as to form a p-in like morphology. [41-45] There are mainly two ways to construct p-in like morphology: 1) sequentially dissolving and processing D and A components in orthogonal solvents; [46] 2) adopting the blade-coating film-forming technology. [47] Due to the similarity of conjugated backbones and side chains of donors and acceptors, it is challenging to find a pair of orthogonal solvents applicable to various donors and acceptors. However, in most labs, spin-coating is still the most common film processing method, which possesses particular advantages in tuning the BHJ morphology due to the larger shear stress. Thereafter, LbL-type OPVs are less studied and their efficiencies are also largely lagging behind those of BHJ-type counterparts. [48] However, LbL-type OPVs might be more suitable for large-area or roll-to-roll fabrications, because they can offer precise control over the morphology of each layer in mass production. [49-51] Obtaining a finely tuned morphology of the active layer to facilitate both charge generation and charge extraction has long been the goal in the field of organic photovoltaics (OPVs). Here, a solution to resolve the above challenge via synergistically combining the layer-by-layer (LbL) procedure and the ternary strategy is proposed and demonstrated. By adding an asymmetric electron acceptor, BTP-S2, with lower miscibility to the binary donor:acceptor host of PM6:BO-4Cl, vertical phase distribution can be formed with donor-enrichment at the anode and accept...

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Adding a Third Component with Reduced Miscibility and Higher LUMO Level Enables Efficient Ternary Organic Solar Cells

Cited by 205 publications

References 66 publications

Reducing V_OC loss via structure compatible and high lowest unoccupied molecular orbital nonfullerene acceptors for over 17%‐efficiency ternary organic photovoltaics

Reducing V_OC loss via structure compatible and high lowest unoccupied molecular orbital nonfullerene acceptors for over 17%‐efficiency ternary organic photovoltaics

Ternary Organic Photovoltaic Cells Exhibiting 17.59% Efficiency with Two Compatible Y6 Derivations as Acceptor

Layer‐by‐Layer Processed Ternary Organic Photovoltaics with Efficiency over 18%

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Adding a Third Component with Reduced Miscibility and Higher LUMO Level Enables Efficient Ternary Organic Solar Cells

Cited by 205 publications

References 66 publications

Reducing VOC loss via structure compatible and high lowest unoccupied molecular orbital nonfullerene acceptors for over 17%‐efficiency ternary organic photovoltaics

Reducing VOC loss via structure compatible and high lowest unoccupied molecular orbital nonfullerene acceptors for over 17%‐efficiency ternary organic photovoltaics

Ternary Organic Photovoltaic Cells Exhibiting 17.59% Efficiency with Two Compatible Y6 Derivations as Acceptor

Layer‐by‐Layer Processed Ternary Organic Photovoltaics with Efficiency over 18%

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Reducing V_OC loss via structure compatible and high lowest unoccupied molecular orbital nonfullerene acceptors for over 17%‐efficiency ternary organic photovoltaics

Reducing V_OC loss via structure compatible and high lowest unoccupied molecular orbital nonfullerene acceptors for over 17%‐efficiency ternary organic photovoltaics