Efficient and stable operation of nonfullerene organic solar cells: retaining a high built-in potential

Wang, Yiwen; Han, Jiayin; Cai, Linfeng; Li, Ning; Li, Zhe; Zhu, Furong

doi:10.1039/d0ta08018g

Cited by 41 publications

(36 citation statements)

References 25 publications

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“…A recent study reported that chemical reaction can occur between PEI (also PEIE) and ITIC molecules, which is also likely in part to be linked to the interfacial reaction caused by the PEDOT:PSS. [ 67–69 ] When PEI makes contact with ITIC, PEI can act as a nucleophile with the carbonyl (CO) groups in INCN, causing the structural change of ITIC and breaking intramolecular π‐electron overlap within the molecule ( Figure 5 a). The bleaching of the absorption peak and concomitant color change reflects the degradation of the electronic structure of ITIC.…”

Section: Recent Progress In Device Performancementioning

confidence: 99%

Recent Progress and Challenges toward Highly Stable Nonfullerene Acceptor‐Based Organic Solar Cells

Wang

Lee

Hou

et al. 2020

Advanced Energy Materials

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197

178

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Organic solar cells (OSCs) based on nonfullerene acceptors (NFAs) have made significant breakthrough in their device performance, now achieving a power conversion efficiency of ≈18% for single junction devices, driven by the rapid development in their molecular design and device engineering in recent years. However, achieving long‐term stability remains a major challenge to overcome for their commercialization, due in large part to the current lack of understanding of their degradation mechanisms as well as the design rules for enhancing their stability. In this review, the recent progress in understanding the degradation mechanisms and enhancing the stability of high performance NFA‐based OSCs is a specific focus. First, an overview of the recent advances in the molecular design and device engineering of several classes of high performance NFA‐based OSCs for various targeted applications is provided, before presenting a critical review of the different degradation mechanisms identified through photochemical‐, photo‐, and morphological degradation pathways. Potential strategies to address these degradation mechanisms for further stability enhancement, from molecular design, interfacial engineering, and morphology control perspectives, are also discussed. Finally, an outlook is given highlighting the remaining key challenges toward achieving the long‐term stability of NFA‐OSCs.

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Section: Recent Progress In Device Performancementioning

confidence: 99%

Recent Progress and Challenges toward Highly Stable Nonfullerene Acceptor‐Based Organic Solar Cells

Wang

Lee

Hou

et al. 2020

Advanced Energy Materials

Self Cite

197

178

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“…The factors that contribute to the reduction in operational efficiency of OPV cells and modules over time are several and have been clearly identified. [320][321][322][323][324][325][326][327][328][329] Degradation factors that are common to all OPV devices include: photochemical and photo physical degradation of the active layer materials and interfaces; [330][331][332] morphological degradation [333,334] due to high thermal stress under operation; as well as, a series of degradation events that can be initiated by the ingress of H 2 O and O 2 in poorly sealed devices. [335][336][337] Additionally, there are some degradation factors specific to OPV modules, including electrical stress [338] and degradation at the cell interconnections.…”

Section: Encapsulation and Stability Testing Of Large Area Devicesmentioning

confidence: 99%

Progress in Upscaling Organic Photovoltaic Devices

Bernardo

Lopes

Lidzey

et al. 2021

Advanced Energy Materials

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Organic photovoltaic (OPV) cells have recently undergone a rapid increase in power conversion efficiency (PCE) under AM1.5G conditions, as certified by the National Renewable Energy Laboratory (NREL), which have jumped from 11.5% in October 2017 to 18.2% in December 2020. However, the NREL certified PCE of large area OPV modules is still lagging far behind (11.7% in July 2020). Additionally, there has been a rapidly growing interest in the use of OPVs for dim light indoor applications, with reported PCE of some large area (≥1 cm2) devices, under 1000 lux, well above 20%. The transition of OPV from the lab to the market requires the development of effective manufacturing processes that can scale‐up laboratory‐scale devices into large area devices, without sacrificing performance and simultaneously minimizing associated manufacturing costs. This review article focuses on four important challenges that OPV technology has to face to achieve a reliable lab‐to‐fab transfer, namely: i) The upscaling of indium‐tin‐oxide (ITO)‐based single cells and the interconnection of single cells into large area modules; ii) the development of alternatives to vacuum processing; iii) the development of alternatives to ITO‐based substrates; and iv) strategies for improving the lifetime of large area OPV devices.

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“…At the present stage, the fundamental identification and understanding of the underlying degradation mechanisms fairly lag behind that of the efficiency development, which originates from the mainstream material design rules and optimization strategies primarily dedicating to PCE enhancement instead of boosting stability. [ 15–17 ] Generally speaking, the inherent instability such as the changes of bulk‐heterojunction (BHJ) morphology and intrinsic attenuation of donor/acceptor (D/A) materials normally occur in the photoactive layers without the influence of the extrinsic factors. [ 18–20 ] Especially, the slow evolution from the initially optimal BHJ morphologies at metastable state to thermodynamically steady case at equilibrium, the aggregation and/or crystallization of NFAs, and the D/A demixing will induce the severe degradation of exciton dissociation, subsequent charge carrier transport, and extraction and give rise to the serious non‐radiative recombination, thereby shortening the lifetime of OPV devices.…”

Section: Introductionmentioning

confidence: 99%

Suppressing Kinetic Aggregation of Non‐Fullerene Acceptor via Versatile Alloy States Enables High‐Efficiency and Stable Ternary Polymer Solar Cells

Zhang

Guo

Zhang

et al. 2021

Adv Funct Materials

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Despite considerable advances devoted to improving the operational stability of organic solar cells (OSCs), the metastable morphology degradation remains a challenging obstacle for their practical application. Herein, the stabilizing function of the alloy states in the photoactive layer from the perspective of controlling the aggregation characteristics of non‐fullerene acceptors (NFAs), is revealed. The alloy‐like model is adopted separately into host donor and acceptor materials of the state‐of‐the‐art binary PM6:BTP‐4Cl blend with the self‐stable polymer acceptor PDI‐2T and small molecule donor DRCN5T as the third components, delivering the simultaneously enhanced photovoltaic efficiency and storage stability. In such ternary systems, two separate arguments can rationalize their operating principles: (1) the acceptor alloys strengthen the conformational rigidity of BTP‐4Cl molecules to restrain the intramolecular vibrations for rapid relaxation of high‐energy excited states to stabilize BTP‐4Cl acceptor. (2) The donor alloys optimize the fibril network microstructure of PM6 polymer to restrict the kinetic diffusion and aggregation of BTP‐4Cl molecules. According to the superior morphological stability, non‐radiative defect trapping coefficients can be drastically reduced without forming the long‐lived, trapped charge species in ternary blends. The results highlight the novel protective mechanisms of engineering the alloy‐like composites for reinforcing the long‐term stability of NFA‐based ternary OSCs.

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Efficient and stable operation of nonfullerene organic solar cells: retaining a high built-in potential

Abstract: Modification of the HTL helps to attain a high built-in potential (V0) across the BHJ by suppressing the interfacial reaction at the HTL/BHJ interface. It is critical to retain a high and steady V0 to obtain efficient and stable nonfullerene OSCs.

Cited by 41 publications

References 25 publications

Recent Progress and Challenges toward Highly Stable Nonfullerene Acceptor‐Based Organic Solar Cells

Recent Progress and Challenges toward Highly Stable Nonfullerene Acceptor‐Based Organic Solar Cells

Progress in Upscaling Organic Photovoltaic Devices

Suppressing Kinetic Aggregation of Non‐Fullerene Acceptor via Versatile Alloy States Enables High‐Efficiency and Stable Ternary Polymer Solar Cells

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