Controllable Exciton Diffusion Length and Ultrafast Charge Generation in Ternary Organic Solar Cells

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Controllable Exciton Diffusion Length and Ultrafast Charge Generation in Ternary Organic Solar Cells

This work demonstrates the feasibility of regulating exciton diffusion and hole transfer to promote efficient charge generation, and achieving high-performance OPV devices by increasing short-circuit current density. Fast and efficient charge generation requires an increased exciton diffusion length and faster hole transfer. In addition, the reduced trap state in the ternary system is also beneficial for reducing recombination of charges. This work reveals the co-mechanism of charge generation and trap state on J SC.


Comprehensive Summary

Charge generation, a critical process in the operation of organic solar cell (OSC), requires thorough investigation in an ultrafast perspective. This work demonstrates that the utilization of alloy model for the non-fullerene acceptor (NFA) component can regulate the crystallization properties of active layer films, which in turn affects exciton diffusion and hole transfer (HT), ultimately influencing the charge generation process. By incorporating BTP-eC7 as a third component, without expanding absorption range or changing molecular energy levels but regulating the ultrafast exciton diffusion and HT processes, the power conversion efficiency (PCE) of the optimized PM6:BTP-eC9:BTP-eC7 based ternary OSC is improved from 17.30% to 17.83%, primarily due to the enhancement of short-circuit current density (J SC). Additionally, the introduction of BTP-eC7 also reduces the trap state density in the photoactive layer which helps to reduce the loss of J SC. This study introduces a novel approach for employing ternary alloy models by incorporating dual acceptors with similar structures, and elucidates the underlying mechanism of charge generation and J SC in ternary OSCs.

Chlorajaponins A—Q, Lindenane‐Related Sesquiterpenoid Dimers from Chloranthus japonicus and Their Biological Activities

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Chlorajaponins A—Q, Lindenane-Related Sesquiterpenoid Dimers from Chloranthus japonicus and Their Biological Activities

Seventeen new lindenane sesquiterpenoid dimers (LSDs), chlorajaponins A—Q (1—17), including two rearranged skeleton meroterpenoids (1—2), and 13 reported analogs (18—30) were isolated from the Chloranthus japonicus Sieb. Compounds 1, 2, and 18 demonstrated significant inhibitory effects on lipid accumulation, dose-dependently reduced TG and TC levels, and significantly downregulated expression of FASN and SERBP1 validated by western blot assay. Moreover, compounds 19—22 and 25 exhibited the most potent anti-inflammatory effects with IC50 values of 7.89, 6.25, 2.98, 10.77, and 3.60 μmol/L, respectively.


Comprehensive Summary

Seventeen undescribed lindenane-related sesquiterpenoid dimers, chlorajaponins A—Q (1—17), and 13 reported analogs (18—30) were isolated from Chloranthus japonicus Sieb. Compound 1 possesses an unprecedented 3/5/7/5/5/6/5/3 fused octacyclic scaffold, featuring a 6(5→4)-abeo-lindenane monomer, while 2 exhibits a 3/5/6/6/5/6/5/3 fused octacyclic scaffold. Their structures were determined through a combination of spectroscopic analyses and X-ray crystallography. Compounds 1, 2, and 18 demonstrated significant inhibitory effects on lipid accumulation and effectively reduced the levels of triglycerides and total cholesterol, as well as the levels of aspartate aminotransferase and alanine aminotransferase in a HepG2 cell model. In addition, compounds 1, 2, and 18 significantly suppressed the protein expression of the fatty acid synthase (FASN) and the sterol regulatory element-binding protein 1 (SREBP1). Moreover, the anti-inflammatory assay showed that compounds 19—22 and 25 inhibited the NO production induced by lipopolysaccharide in RAW 264.7 macrophages with IC50 values of 7.89 ± 0.44, 6.25 ± 0.46, 2.98 ± 0.29, 10.77 ± 0.60, and 3.60 ± 0.28 μmol/L.

Understanding the Interfacial Energy Structure and Electron Extraction Process in Inverted Organic Solar Cells with Phosphine‐Doped Cathode Interlayers

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Understanding the Interfacial Energy Structure and Electron Extraction Process in Inverted Organic Solar Cells with Phosphine-Doped Cathode Interlayers

A series of cross-linked and phosphine-doped cathode interlayers (CILs), namely c-NDI:P0, c-NDI:P1, c-NDI:P2, and c-NDI:P3, are developed for inverted organic solar cells. We elucidate the relationship between the depletion region width at the heterojunction interface and the electron extraction ability of CILs. By incorporating c-NDI:P0, a low depletion width of 0.8 nm along with a high power conversion efficiency (PCE) of 17.7% can be obtained in the inverted OSC based on PBDB-TF:BTP-eC9.


Comprehensive Summary

Cathode interlayers (CILs) play an essential role in achieving efficient organic solar cells (OSCs). However, the electronic structure at the electrode/CIL/active layer interfaces and the underlying mechanisms for electron collection remain unclear, which becomes a major obstacle to develop high-performance CILs. Herein, we investigate the relationship of the electron collection abilities of four cross-linked and n-doped CILs (c-NDI:P0, c-NDI:P1, c-NDI:P2, c-NDI:P3) with their electronic structure of space charge region at heterojunction interface. By accurately calculating the depletion region width according to the barrier height, doping density and permittivity, we put forward that the optimal thickness of CIL should be consistent with the depletion region width to realize the minimum energy loss. As a result, the depletion region width is largely reduced from 13 nm to 0.8 nm at the indium tin oxide (ITO)/c-NDI:P0 interface, resulting in a decent PCE of 17.7% for the corresponding inverted OSCs.

Asymmetric Synthesis of Dihydrospirotryprostatin B via a Silica Gel‐Mediated Cyclization of Tryptamine‐Ynamide

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Asymmetric Synthesis of Dihydrospirotryprostatin B via a Silica Gel-Mediated Cyclization of Tryptamine-Ynamide

An asymmetric synthesis of dihydrospirotryprostatin B was achieved through silica gel-mediated cyclization of tryptamine-ynamide based on a chiral pool strategy.


Comprehensive Summary

An asymmetric synthesis of dihydrospirotryprostatin B was achieved in 15 steps (8 purifications) from L-tryptophan. The main feature of our synthetic strategy is the efficient construction of spirocyclic oxindole intermediate containing a chiral quaternary carbon center, involving the silica gel-mediated cyclization of tryptamine-ynamide and oxidation under neat conditions.

Recent Advance in the Study on 5‐Formylcytosine (f5C) RNA Modification

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Recent Advance in the Study on 5-Formylcytosine (f5C) RNA Modification


Abstract

The widespread involvement of 5-formylcytosine f5C RNA in gene function regulation and its impact on crucial life processes like cell differentiation, embryonic development, and disease development underscores the significance of detecting this specific base modification. This detection holds great importance for basic epigenetics research and the early diagnosis and pathogenesis research of various diseases. This review aims to summarize recent research progress in f5C detection methods using selective chemical labeling, with the hope of aiding future research endeavors.

Investigating Ultrafast Electron Transfer in Graphene and Its Derivatives Composites by Femtosecond Transient Absorption Spectroscopy

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Investigating Ultrafast Electron Transfer in Graphene and Its Derivatives Composites by Femtosecond Transient Absorption Spectroscopy

D−A composites prepared from graphene and its derivatives (GNDs) with photo-sensitizers play an essential role in solar energy conversion. This review summarizes the recent progresses in characterizing GNDs-based composites using transient absorption spectroscopy (TAS) to assess the electronic properties of composites from a photophysical perspective. These enable the design of various more efficient solar energy conversion composites.


Abstract

As excellent functional materials, the composite materials based on graphene and its derivatives (GNDs) have lots of important application values in the emerging fields such as solar energy conversion, and the exploration of electron (or energy) transfer properties of those composites is the key for revealing their further applications. In this review, femtosecond transient absorption spectroscopy (TAS) has been introduced as an essential technique to understand the carrier behaviors in GNDs composites, as well as the advancements of TAS. The specific examples of electron transport in various composite materials characterized by TAS are summarized and discussed, which consist of GNDs with semiconductor quantum dots (QDs), organic dyes, organic polymers, perovskites and other materials, respectively. This review provides a deep insight into the electron transfer (ET) kinetics of various GNDs composites from the perspective of TAS.

Enhance the efficiency of perovskite solar cells using W doped SnO2 electron transporting layer

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Enhance the efficiency of perovskite solar cells using W doped SnO2 electron transporting layer

High quality W doped SnO2 electron transporting layer is prepared using molecular precursor containing SnC2O4 and (NH4)10W12O41 ⋅ xH2O, which could effectively modify the electric conductivity and energy band position of resulting SnO2 film. Therefore, power conversion efficiency of the perovskite solar cells with W doped SnO2 layer are impressively promoted.


Abstract

For low temperature (≤180 °C) processed perovskite solar cells (PSCs), SnO2 has been proven to be one of the most effective electron transporting layer. However, problems, such as poor electric conductivity and high defect density, inevitably exist in the SnO2 films which are fabricated using low temperature solution methods. Element doping of SnO2 film is a feasible strategy to alleviate the above problems. Herein, W doping of the SnO2 is realized through addition of ammonium tungstate hydrate into the molecular precursor of SnO2. The W doped SnO2 film exhibits higher conductivity, and can better extract and transport the electrons from the perovskite films. Hence, power conversion efficiency is boosted from 20.60 % for the reference PSCs to 21.83 % for PSCs fabricated on 2.5 mg mL−1 ammonium tungstate hydrate doped SnO2 films.

Chemical and photophysical properties of amine functionalized bis‐NHC‐pyridine‐RuII complexes

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Chemical and photophysical properties of amine functionalized bis-NHC-pyridine-RuII complexes

Amine substitution in the backbone of a room temperature (r. t.) luminescent C^N^C ruthenium(II) complex alters the excited energy landscape such that at low temperature (l.t.) the typical luminescent relaxation of the 3MLCT (metal-to-ligand charge transfer) to the 1GS (ground state) can occur, but at r. t. a dark relaxation pathway across the 3MC (metal centered) state is activated and a higher photostability is observed.


Abstract

The effects of backbone amine functionalization in three new homoleptic C^N^C type ruthenium(II) complexes bearing a tridentate bis-imidazole-2-ylidene pyridine ligand framework are characterized and studied by single crystal diffraction, electrochemistry, optical spectroscopy and transient absorption spectroscopy in combination with ab initio DFT calculations. Functionalization by dimethylamine groups in 4-position of the pyridine backbone significantly influences the properties of the complexes as revealed by comparison with the unfunctionalized references. As a result of the amine functionalization, a higher molar absorption coefficient of the MLCT bands, a decreased photoluminescence quantum yield at room temperature together with a shortened excited state lifetime but an improved photostability is observed. Introduction of electron donating and withdrawing groups at the NHC unit modifies the electronic and optical properties, such as the oxidation potential, absorption and emission properties, and the lifetimes of the excited states.

Synthesis and Characterization of Dearomatized Pyridine‐Derived Alkyl‐Amido‐tert‐Butylphosphine Iron(II) Complexes

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Synthesis and Characterization of Dearomatized Pyridine-Derived Alkyl-Amido-tert-Butylphosphine Iron(II) Complexes

Little is known about the reactivities of [PN‘−Fe−CH2R] complexes. Until recently, there was little reason to suspect anything interesting about them. However, recent ROMP precatalysts of the [PN‘−Fe−CH2R] formulation from the Milstein group justify fundamental coordination and reactivity studies and herein detail our own efforts.


Abstract

Neutral three-coordinate iron alkylidenes of the form PN−Fe=CHR have been proposed as viable candidates for alkene metathesis. Indeed, during the final stages of preparing this current study, a separate report disclosed that dearomatized PN−Fe-alkyl complexes are active precatalysts for ring-opening metathesis polymerization (ROMP) of norbornene implicating PN−Fe=CHR species as possible intermediates. In yet another separate report, we prepared Zn analogues of PN−Fe-alkyl complexes and herein provide an account for the synthesis, characterization, and reactivity of some new iron complexes with the same tBu substituted PN platform.

Water Adducts of the Lewis Superacids: Tris(pentafluoroethyl)gallane and ‐indane

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Water Adducts of the Lewis Superacids: Tris(pentafluoroethyl)gallane and -indane

Herein we report on the synthesis of tris(pentafluoroethyl)indane, In(C2F5)3. It is accessible in the form of its dihydrate [In(C2F5)3(OH2)2]. An improved synthesis for the gallium analogue [Ga(C2F5)3(OH2)2] is also reported. Due to their stability and convenient accessibility, the hydrates are ideal starting compounds for the chemistry of tris(pentafluoroethyl)gallium and -indium compounds, for example hydroxogallates and -indates.


Abstract

Lewis superacids (LSA) are defined by a fluoride ion affinity (FIA) that exceeds that of SbF5, and are thus characterized as hard according to the HSAB concept. Soft superacidity was defined for compounds exceeding the hydride ion affinity (HIA) of B(C6F5)3. Herein we report on the synthesis of a Lewis acid being superacidic only on the soft regime: tris(pentafluoroethyl)indane, In(C2F5)3. It is accessible in the form of its dihydrate [In(C2F5)3(OH2)2]. An improved synthesis for the gallium analogue [Ga(C2F5)3(OH2)2] is also reported. Tris(pentafluoroethyl)indane dihydrate, [In(C2F5)3(OH2)2], was fully characterized by IR and NMR spectroscopy, as well as by single crystal X-ray diffraction. Due to their stability and convenient accessibility, the hydrates are ideal starting compounds for the chemistry of tris(pentafluoroethyl)gallium and -indium compounds, for example hydroxogallates and -indates. An attempt to determine its gas-phase structure and that of the gallium analogue by electron diffraction demonstrates that they lose water ligands upon evaporation. The energetics of these processes were predicted by quantum-chemical calculations as was the nature of bonding in the free Lewis acids and their mono- and dihydrates. Furthermore, the synthesis and structural diversity of hydroxido tris(pentafluoroethyl) gallates and one indate are presented.