Organic solar cells (OSCs) with nonfullerene acceptors (NFAs) exhibit efficient charge generation under small interfacial energy offsets, leading to over 18 % efficiency for the single‐junction ...devices based on the state‐of‐the‐art NFA of Y6. Herein, to reveal the underlying charge generation mechanisms, we have investigated the exciton binding energy (Eb) in Y6 by a joint theoretical and experimental study. The results show that owing to strong charge polarization effects, Y6 has remarkable small Eb of −0.11–0.15 eV, which is even lower than perovskites in many cases. Moreover, it is peculiar that the photoluminescence is enhanced with temperature, and the energy barrier for separating excitons into charges is evidently lower than the thermal energy according to the temperature dependence of photoluminescence, manifesting direct photogeneration of charge carriers enabled by weak Eb in Y6. Thus, charge generation in NFA‐based OSCs shows little dependence on interfacial driving forces.
Direct photogeneration of free charge carriers enabled by remarkably low exciton binding energies is demonstrated in the state‐of‐the‐art nonfullerene acceptor of Y6 by a joint experimental and theoretical study. This results in efficient charge generation under small interfacial energy offsets in the high‐efficiency nonfullerene organic solar cells.
All-solid-state lithium-based batteries with inorganic solid electrolytes are considered a viable option for electrochemical energy storage applications. However, the application of lithium metal is ...hindered by issues associated with the growth of mossy and dendritic Li morphologies upon prolonged cell cycling and undesired reactions at the electrode/solid electrolyte interface. In this context, alloy materials such as lithium-indium (Li-In) alloys are widely used at the laboratory scale because of their (electro)chemical stability, although no in-depth investigations on their morphological stability have been reported yet. In this work, we report the growth of Li-In dendritic structures when the alloy material is used in combination with a Li
PS
Cl solid electrolyte and Li(Ni
Co
Mn
)O
positive electrode active material and cycled at high currents (e.g., 3.8 mA cm
) and high cathode loading (e.g., 4 mAh cm
). Via ex situ measurements and simulations, we demonstrate that the irregular growth of Li-In dendrites leads to cell short circuits after room-temperature long-term cycling. Furthermore, the difference between Li and Li-In dendrites is investigated and discussed to demonstrate the distinct type of dendrite morphology.
•The relationship between economic activities and air pollution in China is investigated.•The PM2.5 and Air Quality Index of 73 key cities are used to measure air pollution level.•The VECM model, ...impulse response function and variance decomposition are used.•A unidirectional causality between PM2.5 concentrations and economic activities in the long run exists.•There is a bilateral causality between Air Quality Index and the other variables.
In China, smog pollution has become an increasingly serious environmental issue that seriously threatens its sustainable economic development. Given that smog pollution usually becomes more prominent as economic activities increase, this study investigates the causal relationship between the two. Using panel data of 73 key cities in China during 2013–2017, this research employs the VECM, impulse response function, and variance decomposition to conduct empirical estimations. The results indicate that there is a unidirectional causality between PM2.5 and economic growth, Foreign Direct Investment (FDI), and industrial structure in the long-term, while there is bilateral causality between the Air Quality Index and the other variables. This suggests that, in the short term, there is a one-way causality from foreign trade, economic growth, and industrial structure to air pollution. There is also evidence for the existence of inverted U-shaped relationship between smog pollution and economic growth. The responses of smog pollution to the ratio of secondary industry to is positive, suggesting that the increase in the proportion of the secondary industry would increase smog concentrations. The results of variance decomposition suggest that foreign trade contributes the most to air pollution, followed by economic growth, industrial structure, and FDI.
Solution-processable small molecules for organic solar cells have attracted intense attention for their advantages of definite molecular structures compared with their polymer counterparts. However, ...the device efficiencies based on small molecules are still lower than those of polymers, especially for inverted devices, the highest efficiency of which is <9%. Here we report three novel solution-processable small molecules, which contain π-bridges with gradient-decreased electron density and end acceptors substituted with various fluorine atoms (0F, 1F and 2F, respectively). Fluorination leads to an optimal active layer morphology, including an enhanced domain purity, the formation of hierarchical domain size and a directional vertical phase gradation. The optimal morphology balances charge separation and transfer, and facilitates charge collection. As a consequence, fluorinated molecules exhibit excellent inverted device performance, and an average power conversion efficiency of 11.08% is achieved for a two-fluorine atom substituted molecule.
Minimizing energy loss is of critical importance in the pursuit of attaining high-performance organic solar cells. Interestingly, reorganization energy plays a crucial role in photoelectric ...conversion processes. However, the understanding of the relationship between reorganization energy and energy losses has rarely been studied. Here, two acceptors, Qx-1 and Qx-2, were developed. The reorganization energies of these two acceptors during photoelectric conversion processes are substantially smaller than the conventional Y6 acceptor, which is beneficial for improving the exciton lifetime and diffusion length, promoting charge transport, and reducing the energy loss originating from exciton dissociation and non-radiative recombination. So, a high efficiency of 18.2% with high open circuit voltage above 0.93 V in the PM6:Qx-2 blend, accompanies a significantly reduced energy loss of 0.48 eV. This work underlines the importance of the reorganization energy in achieving small energy losses and paves a way to obtain high-performance organic solar cells.
The spectroscopic and photophysical properties of organic materials in the solid‐state are widely accepted as a result of their molecular packing structure and intermolecular interactions, such as J‐ ...and H‐aggregation, charge‐transfer (CT), excimer and exciplex. However, in this work, we show that Spe‐F4DIB cocrystals (SFCs) surprisingly retain the energy levels of photoluminescence (PL) states of Spe crystals, despite a significantly altered molecular packing structure after cocrystallization. In comparison, Npe‐F4DIB cocrystals (NFCs) with new spectroscopic states display different spectra and photophysical behaviors as compared with those of individual component crystals. These may be related to the molecular configuration in crystals, and we propose Spe as an “intramolecular emissive” material, thus providing a new viewpoint on light‐emitting species of organic chromophores. Moreover, the nonlinear optical (NLO) properties of Npe and Spe are firstly demonstrated and modulated by cocrystallization. The established “molecule‐packing‐property” relationship helps to rationally control the optical properties of organic materials through cocrystallization.
Luminescent halogen‐bonded solids: Two new halogen‐bonded cocrystals were prepared and characterized for their crystal structure, self‐assembling manner, spectroscopic, photophysical, and nonlinear optical properties. The molecule‐packing‐property relationship helps to rationally design and prepare cocrystals with desired properties.
Charge transport and polarity in organic D–A mixed‐stack crystals are examined in terms of super‐exchange electronic couplings. When the super‐exchange coupling is dominated by the interaction ...between donor HOMO and acceptor LUMO, ambipolar transport is achieved. Otherwise, involvement of other bridge orbitals can lead to unbalanced, even to unipolar transport in a special case that the HOMO–LUMO interaction vanishes.
Significant improvement in the power conversion efficiency (PCE) of organic solar cells (OSCs) is achieved by developing novel donor and acceptor materials, optimizing the phase‐separation morphology ...via diversified strategies, and using interfacial materials for better charge‐carrier collection. For state‐of‐the‐art devices, a PCE of over 13% is reported. However, simulations indicate that an efficiency of ≈19% could be realized, assuming a total energy loss of 0.5 eV with an external quantum efficiency of 90% and a fill factor of 70%. This large difference between the theoretical calculations and the actual performance of the state‐of‐the‐art devices shows that OSCs have significant potential for the future. Here, the energy loss is discussed, which determines the PCE limit, and then different systems are reviewed, such as small‐molecule (SM)/fullerene blends, polymer/fullerene blends, SM/nonfullerene blends, polymer/nonfullerene blends, and multicomponent systems. After highlighting the factors that have limited the device efficiency to date, an outlook on the most important challenges to guide OSCs toward the 15% PCE regime is provided.
Minimizing the energy loss without reducing the fraction of charge carriers collected is crucial for optimizing the power conversion efficiency of a given material. Different organic‐solar‐cell systems are reviewed. After highlighting the factors that have limited the device efficiency to date, an outlook on the most important challenges to guide organic solar cells toward the 15% power conversion efficiency regime is provided.
The charge transfer and photophysics in a new light‐emitting cocrystal with ribbon‐like morphology are revealed in‐depth. These cocrystals can serve as an efficient 1D optical waveguide, and the ...cocrystal waveguide couplers fabricated by a probe‐assisted crystal‐moving technique exhibit interfacial white emission and can function as basic photonic logic gates, showing potential for future integrated photonics.
Long non-coding RNAs (lncRNAs) regulate gene expression in a variety of ways at epigenetic, chromatin remodeling, transcriptional, and translational levels. Accumulating evidence suggests that lncRNA ...X-inactive specific transcript (lncRNA Xist) serves as an important regulator of cell growth and development. Despites its original roles in X-chromosome dosage compensation, lncRNA Xist also participates in the development of tumor and other human diseases by functioning as a competing endogenous RNA (ceRNA). In this review, we comprehensively summarized recent progress in understanding the cellular functions of lncRNA Xist in mammalian cells and discussed current knowledge regarding the ceRNA network of lncRNA Xist in various diseases. Long non-coding RNAs (lncRNAs) are transcripts that are more than 200 nt in length and without an apparent protein-coding capacity (
Furlan and Rougeulle, 2016
;
Maduro et al., 2016
). These RNAs are believed to be transcribed by the approximately 98–99% non-coding regions of the human genome (
Derrien et al., 2012
;
Fu, 2014
;
Montalbano et al., 2017
;
Slack and Chinnaiyan, 2019
), as well as a large variety of genomic regions, such as exonic, tronic, and intergenic regions. Hence, lncRNAs are also divided into eight categories: Intergenic lncRNAs, Intronic lncRNAs, Enhancer lncRNAs, Promoter lncRNAs, Natural antisense/sense lncRNAs, Small nucleolar RNA-ended lncRNAs (sno-lncRNAs), Bidirectional lncRNAs, and non-poly(A) lncRNAs (
Ma et al., 2013
;
Devaux et al., 2015
;
St Laurent et al., 2015
;
Chen, 2016
;
Quinn and Chang, 2016
;
Richard and Eichhorn, 2018
;
Connerty et al., 2020
). A range of evidence has suggested that lncRNAs function as key regulators in crucial cellular functions, including proliferation, differentiation, apoptosis, migration, and invasion, by regulating the expression level of target genes via epigenomic, transcriptional, or post-transcriptional approaches (
Cao et al., 2018
). Moreover, lncRNAs detected in body fluids were also believed to serve as potential biomarkers for the diagnosis, prognosis, and monitoring of disease progression, and act as novel and potential drug targets for therapeutic exploitation in human disease (
Jiang W. et al., 2018
;
Zhou et al., 2019a
). Long non-coding RNA X-inactive specific transcript (lncRNA Xist) are a set of 15,000–20,000 nt sequences localized in the X chromosome inactivation center (XIC) of chromosome Xq13.2 (
Brown et al., 1992
;
Debrand et al., 1998
;
Kay, 1998
;
Lee et al., 2013
;
da Rocha and Heard, 2017
;
Yang Z. et al., 2018
;
Brockdorff, 2019
). Previous studies have indicated that lncRNA Xist regulate X chromosome inactivation (XCI), resulting in the inheritable silencing of one of the X-chromosomes during female cell development. Also, it serves a vital regulatory function in the whole spectrum of human disease (notably cancer) and can be used as a novel diagnostic and prognostic biomarker and as a potential therapeutic target for human disease in the clinic (
Liu et al., 2018b
;
Deng et al., 2019
;
Dinescu et al., 2019
;
Mutzel and Schulz, 2020
;
Patrat et al., 2020
;
Wang et al., 2020a
). In particular, lncRNA Xist have been demonstrated to be involved in the development of multiple types of tumors including brain tumor, Leukemia, lung cancer, breast cancer, and liver cancer, with the prominent examples outlined in
Table 1
. It was also believed that lncRNA Xist (
Chaligne and Heard, 2014
;
Yang Z. et al., 2018
) contributed to other diseases, such as pulmonary fibrosis, inflammation, neuropathic pain, cardiomyocyte hypertrophy, and osteoarthritis chondrocytes, and more specific details can be found in
Table 2
. This review summarizes the current knowledge on the regulatory mechanisms of lncRNA Xist on both chromosome dosage compensation and pathogenesis (especially cancer) processes, with a focus on the regulatory network of lncRNA Xist in human disease.
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