Correlation of Broad Absorption Band with Small Singlet‐Triplet Energy Gap in Organic Photovoltaics

Fan, Baobing; Gao, Wei; Zhang, Rui; Kaminsky, Werner; Tang, Lingxiao; Lin, Francis R.; Wang, Yiwen; Fan, Qunping; Ma, Wei; Gao, Feng; Jen, Alex K.‐Y.

doi:10.1002/anie.202311559

Cited by 4 publications

(7 citation statements)

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“…Our group further developed a series of NFAs with varied side-group conjugation length. An enhanced SWR absorption is observed for acceptor NFA26 with extended conjugated side-group, i.e., thieno[3,2- b ]thiophene . Meanwhile, we found that the enhanced SWR absorption is accompanied by a reduced singlet–triplet energy gap (Δ E ST ).…”

Section: Biaxially Conjugated Non-fullerene Acceptorsmentioning

confidence: 75%

“…An enhanced SWR absorption is observed for acceptor NFA26 with extended conjugated side-group, i.e., thieno [3,2-b]thiophene. 97 Meanwhile, we found that the enhanced SWR absorption is accompanied by a reduced singlet−triplet energy gap (ΔE ST ). The enhanced SWR absorption leads to higher J SC of relevant OSCs, and the reduced ΔE ST is possibly related to the mitigated nonradiative recombination loss.…”

Section: Extension Of Side-group Conjugationmentioning

confidence: 98%

“…54 The underpinning factors of this general phenomenon were investigated by our group through theoretical modeling in nonfullerene systems. 97 Figure 15C depicts the structures of NFAs with extended side-chain conjugation used for the investigation. Compared with Y6-DT that has the aliphatic side-chains on the outward thiophene of π-core, 98 DT-TBr and DT-TTBr have aromatic side-chains with gradually extended conjugation length.…”

Section: Structure−property Relationshipmentioning

confidence: 99%

Section: Structure–property Relationshipmentioning

confidence: 99%

“…The underpinning factors of this general phenomenon were investigated by our group through theoretical modeling in nonfullerene systems Figure C depicts the structures of NFAs with extended side-chain conjugation used for the investigation.…”

Section: Structure–property Relationshipmentioning

confidence: 99%

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Biaxially Conjugated Materials for Organic Solar Cells

Fan,

Gao,

Jen

2023

ACS Nano

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Organic solar cells (OSCs) represent one of the most important emerging photovoltaic technologies that can implement solar energy conversion efficiently. The chemical structure of organic semiconductors deployed in the active layer of OSCs plays a critical role in the photovoltaic performance and chemical/physical stability of relevant devices. With the structure innovation of organic semiconductors, especially nonfullerene acceptors (NFAs), the performance of OSCs have been promoted rapidly in recent years, with state-of-theart power conversion efficiencies (PCEs) exceeding 19.5%. Compared with other photovoltaics like perovskite, the shortcoming of OSCs mainly lies in the high nonradiative recombination loss. However, the photocurrent density is superior in OSCs owing to the easy modulation of the NFA band gap toward the near-infrared region. In these regards, the effort to further boost the PCE of OSCs to achieve a milestone >21% should be devoted to reducing the nonradiative loss while further broadening the absorption band. Developing organic semiconductors with biaxially extended conjugated structures has provided a potential solution to achieve these goals. Herein, we summarize the design rules and performance progress of biaxially extended conjugated materials for OSCs. The descriptions are divided into two major categories, i.e., polymers and NFAs. For p-type polymers, we focus on the biaxial conjugation on some representative building blocks, e.g., polythiophene, triphenylamine, and quinoxaline. Whereas for n-type polymers, some structures with large conjugated planes in the normal direction are presented. We also elaborate on the biaxial conjugation strategies in NFAs with modification site at either the π-core or side-group. The general structure−property relationships are further retrieved within these materials, with focus on the short-wavelength absorption and nonradiative energy loss. Finally, we provide an outlook for the further structure modification strategies of biaxially conjugated materials toward highly efficient, stable, and industry-compatible OSCs.

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Section: Biaxially Conjugated Non-fullerene Acceptorsmentioning

confidence: 75%

Section: Extension Of Side-group Conjugationmentioning

confidence: 98%

Section: Structure−property Relationshipmentioning

confidence: 99%

Section: Structure–property Relationshipmentioning

confidence: 99%

Section: Structure–property Relationshipmentioning

confidence: 99%

See 3 more Smart Citations

Biaxially Conjugated Materials for Organic Solar Cells

Fan,

Gao,

Jen

2023

ACS Nano

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Efficient Dual Mechanisms Boost the Efficiency of Ternary Solar Cells with Two Compatible Polymer Donors to Exceed 19%

Liu,

Wang,

Wen

et al. 2024

Advanced Materials

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Ternary strategy, introducing a third component into binary blend, opens a simple and promising avenue to improve the power conversion efficiency (PCE) of organic solar cells (OSCs). It is worth noting that the introduction of wide bandgap polymer donors (PDs) as the third component can not only better utilize sunlight but also has the potential to improve the mechanical and thermal stability of the active layer. However, efficient ternary OSCs (TOSCs) with two PDs are rarely reported due to the inferior compatibility of polymers and shortage of efficient PDs to match with non‐fullerene acceptors. Herein, two PDs with different end‐group elements (PBB‐F and PBB‐Cl) are adopted in the dual‐PDs ternary systems to explore the underlying mechanisms and improve their photovoltaic performance. The findings demonstrate that the third components exhibit excellent miscibility with PM6 and are embedded in the host donor to form alloy‐like phase, which plays a crucial role in optimizing film morphology. A more profound mechanism for enhancing efficiency through dual mechanisms, that are the guest energy transfer to PM6 and charge transport at the donor/acceptor interface, has been proposed. Consequently, the PM6:PBB‐Cl:BTP‐eC9 TOSCs achieve impressive PCE of over 19%. Furthermore, the TOSCs exhibit better thermal stability than that of binary OSCs due to the reduction in spatial site resistance resulting from a more tightly entangled long‐chain structure. This work not only provides an effective approach to fabricate high‐performance TOSCs, but also demonstrates the importance of developing dual compatible PD materials.This article is protected by copyright. All rights reserved

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Non‐fullerene acceptors with heteroatom substitution on the core moiety for efficient organic photovoltaics

Qi,

Fan,

Fan

et al. 2024

InfoMat

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Organic photovoltaics (OPVs) represent one of the most promising photovoltaic technologies owing to their high capacity to convert solar energy to electricity. With the continuous structure upgradation of photovoltaic materials, especially that of non‐fullerene acceptors (NFAs), the OPV field has witnessed rapid progress with power conversion efficiency (PCE) exceeding 19%. However, it remains challenging to overcome the intrinsic trade‐off between the photocurrent and photovoltage, restricting the further promotion of the OPV efficiency. In this regard, it is urgent to further tailor the structure of NFAs to broaden their absorption spectra while mitigating the energy loss of relevant devices concomitantly. Heteroatom substitution on the fused‐ring π‐core of NFAs is an efficient way to achieve this goal. In addition to improve the near‐infrared light harvest by strengthening the intramolecular charge transfer, it can also enhance the molecular stacking via forming multiple noncovalent interactions, which is favorable for reducing the energetic disorder. Therefore, in this review we focus on the design rules of NFAs, including the polymerized NFAs, of which the core moiety is substituted by various kinds of heteroatoms. We also afford a comprehensive understanding on the structure–property−performance relationships of these NFAs. Finally, we anticipate the challenges restricting the efficiency promotion and industrial utilization of OPV, and provide potential solutions based on the further heteroatom optimization on NFA core‐moiety.image

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Correlation of Broad Absorption Band with Small Singlet‐Triplet Energy Gap in Organic Photovoltaics

Cited by 4 publications

References 50 publications

Biaxially Conjugated Materials for Organic Solar Cells

Biaxially Conjugated Materials for Organic Solar Cells

Efficient Dual Mechanisms Boost the Efficiency of Ternary Solar Cells with Two Compatible Polymer Donors to Exceed 19%

Non‐fullerene acceptors with heteroatom substitution on the core moiety for efficient organic photovoltaics

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