| 1. |
- He, Chengliang, et al.
(författare)
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Near infrared electron acceptors with a photoresponse beyond 1000 nm for highly efficient organic solar cells
- 2020
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Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 8:35, s. 18154-18161
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Tidskriftsartikel (refereegranskat)abstract
- Developing near infrared (NIR) organic semiconductors is indispensable for promoting the performance of organic solar cells (OSCs), but addressing the trade-off between voltage and current density thus achieving high efficiency with low energy loss is still an urgent challenge. Herein, NIR acceptors (H1, H2 and H3) with a photoresponse beyond 1000 nm were developed by conjugating dithienopyrrolobenzothiadiazole to 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrileviavaried alkyl thiophene bridges. It was found that the linear outward chains in thiophene bridges could mitigate both the conformation disorder of H3 and the electronic disorder of the PBDB-T:H3 blends, which could help to form a favorable blend morphology, facilitating highly efficient photoelectric conversion in the resultant OSCs. As a result, devices based on PBDB-T:H3 achieve a high efficiency of 13.75% with a low energy loss of 0.55 eV, which is one of the highest efficiencies and the lowest energy loss among OSCs with an optoelectronic response near 1000 nm. This work provides a new design strategy towards NIR acceptors for efficient OSCs and future exploration of functional optoelectronics.
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| 2. |
- He, Chengliang, et al.
(författare)
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Asymmetric electron acceptor enables highly luminescent organic solar cells with certified efficiency over 18%
- 2022
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Ingår i: Nature Communications. - : NATURE PORTFOLIO. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Enhancing the luminescence property without sacrificing the charge collection is one key to high-performance organic solar cells (OSCs), while limited by the severe non-radiative charge recombination. Here, we demonstrate efficient OSCs with high luminescence via the design and synthesis of an asymmetric non-fullerene acceptor, BO-5Cl. Blending BO-5Cl with the PM6 donor leads to a record-high electroluminescence external quantum efficiency of 0.1%, which results in a low non-radiative voltage loss of 0.178 eV and a power conversion efficiency (PCE) over 15%. Importantly, incorporating BO-5Cl as the third component into a widely-studied donor:acceptor (D:A) blend, PM6:BO-4Cl, allows device displaying a high certified PCE of 18.2%. Our joint experimental and theoretical studies unveil that more diverse D:A interfacial conformations formed by asymmetric acceptor induce optimized blend interfacial energetics, which contributes to the improved device performance via balancing charge generation and recombination. High-performance organic solar cells call for novel designs of acceptor molecules. Here, He et al. design and synthesize a non-fullerene acceptor with an asymmetric structure for diverse donor:acceptor interfacial conformations and report a certificated power conversion efficiency of 18.2%.
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| 3. |
- Li, Yaokai, et al.
(författare)
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Mechanism study on organic ternary photovoltaics with 18.3% certified efficiency: from molecule to device
- 2022
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Ingår i: Energy & Environmental Science. - : ROYAL SOC CHEMISTRY. - 1754-5692 .- 1754-5706. ; 15:2, s. 855-865
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Tidskriftsartikel (refereegranskat)abstract
- Multi-component organic photovoltaics (OPVs), e.g., ternary blends, are effective for high performance, while the fundamental understanding from the molecular to device level is lacking. To address this issue, we here systematically study the working mechanism of ternary OPVs based on non-fullerene acceptors (NFAs). With both molecular dynamics simulations and morphology characterization, we identify that when adding another larger band gap and highly miscible NFA, namely IT-4F or BTP-S2, into the PBDB-TF:BTP-eC9 blend, the NFAs undergo molecular intermixing selectively with BTP-eC9. This causes the composition-dependent band gap and charge recombination, and hence the composition-dependent V-OC. While the charge recombination still dominantly occurs at the PBDB-TF:BTP-eC9 interface, BTP-S2 or IT-4F plays an auxiliary role in facilitating charge transfer and suppressing non-radiative decay. Interestingly, intermolecular end-group packing in the intermixed blend is improved compared to that in pristine films, leading to higher carrier mobility. These synergistic effects significantly improve the power conversion efficiency of the device to an outstanding value of 18.7% (certified value of 18.3%).
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