Swift Electrofluorochromism of Donor–Acceptor Conjugated Polytriphenylamines

Electrofluorochromic (EFC) materials, which exhibit electrochemically controllable fluorescence, hold great promise in optoelectronic devices and biological analysis. Here we design such donor–acceptor (D−A) conjugated polymersP­(TPACO) and P­(TCEC)that contain the same electron-rich and oxidizable polytriphenylamine (PTPA) as π-backbone, yet with different electron-deficient ketone and cyano units as pendant groups, respectively. They both exhibit solvatochromic effects due to intrinsic characteristics of intramolecular charge transfer (ICT). Compared to P­(TPACO), P­(TCEC) shows stronger ICT, which leads to higher electrochemical oxidation potential and lower ion diffusion coefficient. Moreover, both polymers present simultaneous electrochromic (EC) and EFC behaviors with multistate display and remarkably rapid fluorescence response. The response time of P­(TPACO) is as short as 0.19 s, nearly 4-fold faster than that of P­(TCEC) (0.92 s). Such rapid response is found to be determined by the ion diffusion coefficient which is associated with the ICT nature. Finally, the EFC display device based on P­(TPACO) is successfully demonstrated, which shows green fluorescence ON/OFF switching upon applied potentials. This work has successfully demonstrated that swift EFCs can be achieved by rational modulation of the ICT effect in such D–A conjugated polymers

Non-Thermal Annealing Fabrication of Efficient Planar Perovskite Solar Cells with Inclusion of NH₄Cl

Non-Thermal Annealing Fabrication of Efficient Planar Perovskite Solar Cells with Inclusion of NH₄C

2D/1A Strategy to Regulate Film Morphology for Efficient and Stable Nonfullerene Organic Solar Cells

Recently, the ternary blend method has been successfully applied to nonfullerene organic solar cells (OSCs) and enhanced the device performance by utilizing complementary optical absorption. Here we demonstrate the two polymer donors and one small-molecule acceptor (i.e., 2D/1A) strategy to finely regulate the blend film morphology in fullerene-free OSCs. One crystalline polymer donor, PffBT4T–2OD, can act as an effective morphology regulator for a benchmark blend of PTB7–Th and ITIC, leading to appropriate phase-separated morphology, suppressed charge recombination, efficient charge transport and high carrier mobility. The resulting solvent additive- and annealing-free fabricated bulk-heterojunction OSCs show the best power conversion efficiency (PCE) of 8.22% with a significant increase of fill factor compared to their binary counterparts. Importantly, such ternary OSCs when processed under ambient condition retain excellent device performance with a PCE of 7.57%, indicative of good air-stability

Efficient and Balanced Charge Transport Revealed in Planar Perovskite Solar Cells

Hybrid organic–inorganic perovskites have emerged as novel photovoltaic materials and hold great promise for realization of high-efficiency thin film solar modules. In this study, we unveil the ambipolar characteristics of perovskites by employing the transport measurement techniques of charge extraction by linearly increasing voltage (CELIV) and time-of-flight (TOF). These two complementary methods are combined to quantitatively determine the mobilities of hole and electron of CH₃NH₃PbI₃ perovskite while revealing the recombination process and trap states. It is revealed that efficient and balanced transport is achieved in both CH₃NH₃PbI₃ neat film and CH₃NH₃PbI₃/PC₆₁BM bilayer solar cells. Moreover, with the insertion of PC₆₁BM, both hole and electron mobilities of CH₃NH₃PbI₃ are doubled. This study offers a dynamic understanding of the operation of perovskite solar cells

Light and Thermally Induced Evolutional Charge Transport in CH₃NH₃PbI₃ Perovskite Solar Cells

Pre-exposure of perovskite solar cells to light or heat can greatly improve their performance, yet the underlying physical mechanisms are still obscure. Herein we systematically investigate the influences of light soaking and thermal phase transition on charge transport dynamics in two-step fabricated CH₃NH₃PbI₃ perovskite solar cells. By applying the time-of-flight (TOF) measurement under various light illumination times, we not only confirm the existence of nondispersive charge transport in perovskite solar cells but also directly observe a shallow trap filling process and thus increased charge mobility upon light soaking. We further employ the delay-time-dependent charge extraction by linearly increasing voltage (CELIV) technique to reveal that dispersive bimolecular recombination is also largely inhibited. On the other hand, we conduct temperature-dependent TOF and electrical conductivity studies and surprisingly find a rapid change of both hole and electron mobilities during phase transition from tetragonal to cubic crystalline structures at around 310–330 K until reaching a balance of charge transport

Tunable Exciton Dissociation at the Organic/Metal Electrode Interface

Understanding of the dynamic optoelectronic processes at the organic/metal electrode interface is crucial to the interface engineering of organic electronics. Here we present the systematic studies of exciton dissociation of p-type organic semiconductor at the organic/Ag interface. The interfacial dissociation of photogenerated excitons at the <i>N</i>,<i>N</i>′-di­(1-naphthyl)-<i>N</i>,<i>N</i>′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB)/Ag interface was systematically investigated using the transient photovoltage technique as a proof-of-concept. The results indicate that two types of exciton dissociationtransfer of either electrons or holes to the metal electrodecoexist at the organic/metal electrode interface. This conclusion is further confirmed by two additional experimentsthe current response of the NPB/Ag interface to light illumination under constant biases and the successive light current–voltage measurements under constant illumination. Moreover, the proportion of two types of dissociations was found to be tunable upon the oxidation of the silver electrode or the insertion of a lithium fluoride interlayer to the NPB/Ag interface. These results may be useful for interface engineering of organic photovoltaic cells

Hot-Injection Synthesis of Cu-Doped Cu₂ZnSnSe₄ Nanocrystals to Reach Thermoelectric <i>zT</i> of 0.70 at 450 °C

As a new class of potential midrange temperature thermoelectric materials, quaternary chalcogenides like Cu₂ZnSnS₄ (CZTS) and Cu₂ZnSnSe₄ (CZTSe) suffer from low electrical conductivity due to insufficient doping. In this work, Cu-doped CZTSe nanocrystals consisting of polygon-like nanoparticles are synthesized with sufficient Cu doping contents. The hot-injection synthetic method, rather than the traditional one-pot method, in combination with the hot-pressing method is employed to produce the CZTSe nanocrystals. In Cu-doped CZTSe nanocrystals, the electrical conductivity is enhanced by substitution of Zn²⁺ with Cu⁺, which introduces additional holes as charge carriers. Meanwhile, the existence of boundaries between nanoparticles in as-synthesized CZTSe nanocrystals collectively results in intensive phonon-boundary scatterings, which remarkably reduce the lattice thermal conductivity. As a result, an average thermoelectric figure of merit of 0.70 is obtained at 450 °C, which is significantly larger than that of the state-of-the-art quaternary chalcogenides thermoelectric materials. The theoretical calculations from the Boltzmann transport equations and the modified effective medium approximation are in good agreement with the experimental data

Correlating Molecular Structures with Transport Dynamics in High-Efficiency Small-Molecule Organic Photovoltaics

Efficient charge transport is a key step toward high efficiency in small-molecule organic photovoltaics. Here we applied time-of-flight and organic field-effect transistor to complementarily study the influences of molecular structure, trap states, and molecular orientation on charge transport of small-molecule DRCN7T (D1) and its analogue DERHD7T (D2). It is revealed that, despite the subtle difference of the chemical structures, D1 exhibits higher charge mobility, the absence of shallow traps, and better photosensitivity than D2. Moreover, charge transport is favored in the out-of-plane structure within D1-based organic solar cells, while D2 prefers in-plane charge transport

Additional file 1 of Multi-omics reveal mechanisms of high enteral starch diet mediated colonic dysbiosis via microbiome-host interactions in young ruminant

Additional file 1: Table S1. Ingredient and chemical composition of the basal diet. Table S2. The specific primers for the qPCR of β-Actin and tested mRNAs. Table S3. Effects of different hindgut enteral starch diets on the rumen fermentation parameters in growing goats. Table S4. The origin of metabolites. Figure S1. The flow chart of the present study. Figure S2. Fecal evaluation system for dairy goats. Figure S3. The dry matter intake (DMI) and content of luminal nutrients (n = 20 for DMI, and n = 8 for luminal content of nutrients). Figure S4. The gene expression of colonic bile acids receptors (n = 6). Figure S5. Spearman correlation among the host phenotypes, nutrients, microbes, and microbial functions