Search

Miniaturized spectrometers that are absent of bulky dispersive optical elements have received more and more attention. However, most of these advancements have been demonstrated in the visible spectrum. Among the various near‐infrared (NIR) absorbers, organic donor–acceptor blends exhibit a distinctive red‐shifted intermolecular charge‐transfer (CT) state absorption, allowing for the detection of NIR photons below the distinct molecular band edge. Nevertheless, the sub‐bandgap absorption cross‐section has been rather limited. In this study, this challenge is addressed by integrating a metal–dielectric (M–D) microcavity into a prototype (PM6:Y6) model system, with a band‐edge positioned at 869 nm. As a result, an amplified narrowband detection, demonstrating an external quantum efficiency of ≈26% at 905 nm is achieved. Furthermore, the manipulation of the cavity lengths enables easy fine‐tuning of the narrowband spectral response within the 850–960 nm range. Leveraging a spectrum reconstruction algorithm, a spectral detector with 10 nm resolution under a zero bias, validating the potential of utilizing sub‐bandgap CT state absorption for efficient narrowband detectors and micro‐spectrometers is obtained. [ABSTRACT FROM AUTHOR]

Many practical industrial processes require gas–liquid mass transfer in highly viscous liquids, and liquid viscosity affects bubble characteristics and gas–liquid mass transfer. The current study investigated the effects of liquid viscosity on bubble dynamics and gas–liquid mass transfer via shadow imaging and dynamic oxygen dissolution methods, and the influence of fluid viscosity on the hydrodynamic effect when using a wire mesh-coupled solid particles method. The coupling strategy was associated with a bubble size regulation effect, with greater viscosity increasing the gas–liquid interface area by 27%–55% compared with unreinforced gas–liquid flow, which was superior to embedded wire mesh and added solid particles methods. Increased viscosity weakened the mass transfer enhancement effect of the coupling method, but the coupling method still effectively enhanced the gas–liquid mass transfer process, increasing the volumetric mass transfer coefficient (KLa) by 80%–130% compared to non-enhanced gas–liquid flow. Novel empirical KLa correlation equations were developed to predict the effects of the coupling method on gas–liquid mass transfer processes, and those equations exhibited good reliability and predictive capacity. [ABSTRACT FROM AUTHOR]

Pinpointing the origin of inefficiency can expedite the process of optimizing the efficiency of perovskite photovoltaics. However, it is challenging to discern and quantify the different loss pathways in a complete perovskite photovoltaic device under operational conditions. To address this challenge, a modified diode (MD) model is proposed that can quantify bulk/interface defect‐assisted recombination and series/shunt resistive losses. By adopting drift‐diffusion simulation as the benchmark, the physical meanings of the MD model parameters are explored and the performance of the model for simulation parameters spanning many orders of magnitude is evaluated. The evaluation shows that in most practical cases, the proposed model can accurately quantify all the aforementioned losses, and in some special cases, it is possible to identify the predominant loss pathway. Moreover, the MD model is applied to lab‐produced devices (based on Cs0.05FA0.95PbI3 perovskites), demonstrating its effectiveness in quantifying entangled losses in practice. Finally, a set of guidelines for applying the MD model and interpreting the results is provided. [ABSTRACT FROM AUTHOR]

Inorganic tin–lead alloyed perovskite solar cells with optimal bandgap have gained increasing attention because of their higher theoretical efficiency limit, inherently robust stability, and potentials in all‐inorganic perovskite tandems. However, their efficiency has far lagged from their Pb‐based counterparts owing to some intractable problems such as poor crystallization and facile Sn2+ oxidation. Here, a small amount of 2D perovskite PEAPb0.7Sn0.3I4 is utilized to regulate the crystallization process of 3D CsPb0.7Sn0.3I3 based on the temperature‐gradient annealing method. The X‐ray diffraction results show that a stable intermediate phase composed of 3D perovskite seeds and 2D phases is formed under a lower annealing temperature of 50 °C, and the pre‐crystallized 3D perovskites can promote the subsequent crystallization upon 80 °C annealing to attain high quality film. It is interesting that the 2D perovskite phase is ultimately mainly located between the 3D perovskite phase and hole transport layer as revealed by the time of flight‐secondary ion mass spectrometry. The resulting perovskite exhibits a lower extent of non‐radiative recombination and better stability. Consequently, the device achieves a champion efficiency of 14.6% setting a new record for inorganic tin‐lead perovskite solar cells (PSCs). This work sheds more light on the future progress of inorganic tin‐lead PSC. [ABSTRACT FROM AUTHOR]

Ion migration is regarded as the chief culprit for the long-term instability in perovskite solar cells (PSCs), and iodine ions are the most subjects to migration in PSCs. Strategies, such as grain size engineering, chemical bonding engineering, steric impediment effect, and interface passivation, are employed to suppress the iodine migration but unfortunately are unable to completely eliminate it. Here, the influence of the dipole moment of A-site ions on iodine migration has been comprehensively investigated for perovskite films based on different A-site cations via a transient ion drift (TID) method. TID results demonstrate that the decrease in the strength of the dipole moment of A-site ions can lead to a decrease in the activation energy (EA) of iodine ions. Therefore, this work suggests that increasing the strength of dipole moment of A-site ions can be utilized as an effective strategy for suppressing iodine migration in perovskite films providing critical insight for enhancing the long-term stability for PSCs. [ABSTRACT FROM AUTHOR]

Lead halide perovskites possess heavy elements and excellent mobility‐lifetime (µτ) product, becoming desirable candidates for X‐ray detectors. However, current perovskite photoconduction detectors (PCDs) with vertical geometry, where electronic signals and mobile ions share the same conduction path, are facing with extremely challenging ion‐migration issue. Herein, a hybrid X‐ray detector device structure, in which perovskite is vertically stacked onto an indium oxide (In2O3) transistor with lateral transport geometry is designed, perovskite mainly acts as X‐ray sensitizer to activate In2O3 conduction channel, the actual electrical signal is conducted and collected in the lateral metal‐oxide device. With the decoupled ionic and electronic transportation, hybrid detectors are insensitive to the ionic motion of perovskite, hence demonstrating no hysteresis and almost no shifting of baseline that are often observed in PCDs, hybrid detectors also exhibit reduced dark current, improved response time, and four times higher photocurrent signals. Finally, array integration of hybrid detectors and preliminary X‐ray imaging is realized. The work provides an effective device strategy in addition to the mere material alternations to attain high‐performance perovskite‐based X‐ray detectors and arrays. [ABSTRACT FROM AUTHOR]

The traditional way to stabilize α‐phase formamidinium lead triiodide (FAPbI3) perovskite often involves considerable additions of methylammonium (MA) and bromide into the perovskite lattice, leading to an enlarged bandgap and reduced thermal stability. This work shows a seed‐assisted growth strategy to induce a bottom‐up crystallization of MA‐free perovskite, by introducing a small amount of α‐CsPbBr3/DMSO (5%) as seeds into the pristine FAPbI3 system. During the initial crystalization period, the typical hexagonal α‐FAPbI3 crystals (containing α‐CsPbBr3 seeds) are directly formed even at ambient temperature, as observed by laser scanning confocal microscopy. It indicates that these seeds can promote the formation and stabilization of α‐FAPbI3 below the thermodynamic phase‐transition temperature. After annealing not beyond 100 °C, CsPbBr3 seeds homogeneously diffused into the entire perovskite layer via an ions exchange process. This work demonstrates an efficiency of 22% with hysteresis‐free inverted perovskite solar cells (PSCs), one of the highest performances for MA‐free inverted PSCs. Despite absented passivation processes, open‐circuit voltage is improved by 100 millivolts compared to the control devices with the same stoichiometry, and long‐term operational stability retained 92% under continuous full sun illumination. Going MA‐free and low‐temperature processes are a new insight for compatibility with tandems or flexible PSCs. [ABSTRACT FROM AUTHOR]

Nucleic acids are natural macromolecules with the ability to store and transmit information based on the strict base‐pairing principle. Beyond the natural nucleic acid double helixes, various DNA/RNA nanostructures with customized geometries and functionalities have been fabricated. Featured with programmability and sequence‐dependent responsiveness, DNA/RNA nanostructures have been employed for the rational design and construction of logic devices. When stimulated by internal molecular triggers and/or external stimuli, these logic gate devices can operate at nanoscale level in complex biological environments, performing logic operations and producing corresponding outputs. In this minireview, we summarize the recent advances of nucleic acid logic devices, which are responsive to various stimuli, including DNA/RNA strands, metal ions, small molecules, peptides, proteins, photo‐irradiation, pH changes, and so forth. The applications of these devices in biosensing and biofunction regulation are also included. In the last part of the present study, we discuss the remaining challenges and perspectives of nucleic acid logic devices. [ABSTRACT FROM AUTHOR]

Achieving high efficiency at high luminance is one of the most important prerequisites towards practical application of any kind of light‐emitting diode (LED). Herein, we report highly emissive organic fluorescent molecules based on phenanthroimidazole‐benzothiadiazole derivatives capable of maintaining high external quantum efficiency (EQE) at high luminance enabled by triplet–triplet fusion (TTF) in doped organic LEDs. The PIBzP‐, PIBzPCN‐, and PIBzTPA‐based devices showed EQEs of 8.27, 9.15, and 8.64 %, respectively, at luminance of higher than 1000 cd m−2, with little efficiency roll‐off. [ABSTRACT FROM AUTHOR]

Red emission is one of the three primary colors and is indispensable for full color displays. Fluorescent materials that can generate efficient red electroluminescence (EL) are limited and need to be developed. In this work, we report efficient red emitters based on phenanthro[9,10‐d]imidazole‐naphtho[2,3‐c][1,2,5]thiadiazole donor‐acceptor derivatives. The molecules, abbreviated as PINzP and PINzPCN, exhibited high photoluminescence quantum yield (PLQY) up to unity in doped films. They can also reach a relatively high PLQY of ∼30% in neat films. PINzP and PINzPCN were capable of generating efficient red EL in doped devices with a maximum external quantum efficiency (EQE) of 6.96% and 5.92%, respectively. [ABSTRACT FROM AUTHOR]

Behaviors of BDE-28 and BDE-47 in two distinct soils (Phaeozem and Acrisol) as affected by the separate addition of root exudate components (i.e., oxalic acid, glycine, and fructose) were investigated by a soil microcosm incubation experiment. The results showed that root exudate components promoted the desorption of BDE-28 (57.6-235.0 %) and BDE-47 (56.9-223.7 %) from the soils due to the enhancement of their water solubilities. The addition of root exudate components increased the n-butanol extractability of BDE-28 and BDE-47 by 20.3-72.5 and 48.6-169.2 %, respectively, which had a positive correlation with the concentrations of dissolved organic carbon (DOC) in the soils ( p < 0.01), suggesting that the increase of DOC in the soils by root exudate components was the major factor to enhance the extractability. Fructose and oxalic acid promoted the desorption and increased the availability of BDE-28 and BDE-47 in the soils more efficiently than glycine. The addition of different root exudate components resulted in distinct shifts in soil microbial community structure ( p < 0.05). Oxalic acid caused the greatest impacts on the soil bacterial communities and increased the degradation rates of BDE-28 and BDE-47 most obviously. The findings of this study clarified the roles of root exudate components in affecting the behaviors of polybrominated diphenyl ethers (PBDEs) in soils. [ABSTRACT FROM AUTHOR]

This study presents a detailed kinetic investigation on the uptake, acropetal translocation and transformation of BDE-47, 6-OH-BDE-47 and 6-MeO-BDE-47 in maize ( Zea mays L.) by hydroponic exposure. Root uptake followed the order: BDE-47 > 6-MeO-BDE-47 > 6-OH-BDE-47, while 6-OH-BDE-47 was the most prone to acropetal translocation. Debromination rates of BDE-47 were 1.31 and 1.46 times greater than the hydroxylation and methoxylation rates, respectively. Transformation from BDE-47 to lower brominated OH/MeO-PBDEs occurred mainly through debromination first followed by hydroxylation or methoxylation. There was no transformation from 6-OH-BDE-47 or 6-MeO-BDE-47 to PBDEs. Methylation rate of 6-OH-BDE-47 was twice as high as that of 6-MeO-BDE-47 hydroxylation, indicating methylation of 6-OH-BDE-47 was easier and more rapid than hydroxylation of 6-MeO-BDE-47. Debromination and isomerization were potential metabolic pathways for 6-OH-BDE-47 and 6-MeO-BDE-47 in maize. This study provides important information for better understanding the mechanism on plant uptake and transformation of PBDEs. [ABSTRACT FROM AUTHOR]

Metal(loid)s in sewage sludge (SS) are effectively immobilized after pyrolysis. However, the bioavailability and fate of the immobilized metal(loid)s in SS-derived biochar (SSB) following land application remain largely unknown. Here, the speciation and bioavailability evolution of SSB-borne Cr and Zn in soil were systematically investigated by combining pot and field trials and X-ray absorption spectroscopy. Results showed that approximately 58% of Cr existing as Cr(III)-humic complex in SS were transformed into Fe (hydr)oxide-bound Cr(III), while nano-ZnS in SS was transformed into stable ZnS and ferrihydrite-bound species (accounting for over 90% of Zn in SSB) during pyrolysis. All immobilized metal(loid)s, including Cr and Zn, in SSB tended to be slowly remobilized during aging in soil. This study highlighted that SSB acted as a dual role of source and sink of metal(loid)s in soil and posed potential risks by serving a greater role of a metal(loid) source than a sink when applied to uncontaminated soils. Nevertheless, SSB could impede the translocation of metal(loid)s from soil to crop compared to SS, where coexisting elements, including Fe, P, and Zn, played critical roles. These findings provide new insights for understanding the fate of SSB-borne metal(loid)s in soil and assessing the viability of pyrolyzing SS for land application.

Upconverting infrared light into visible light via the triplet-triplet annihilation process in solid state is important for various applications including photovoltaics, photodetection, and bioimaging. Although inorganic semiconductors with broad absorption and negligible exchange energy loss have emerged as promising alternative to molecular sensitizers, currently, they have exclusively suffered from low efficiency and contained toxic elements in near-infrared (NIR)-to-visible upconversion. Here, we report an ultrathin bilayer film for NIR-to-visible upconversion based on atomically thin two-dimensional (2D) monolayer semiconductors. The atomic flatness and strong light absorption of 2D monolayer semiconductors enable ultrafast energy transfer and robust NIR-to-visible emission with a high upconversion quantum yield (1.1 ± 0.2%) at modest incident power (260 mW cm -2 ). Increasing layer thickness adversely quenches the upconversion emission, highlighting the 2D advantage. Considering the whole library of 2D semiconductors, the facile large-scale production and the ultrathin solid-state architecture open a new research field for solid-state upconversion applications.

Achieving high efficiency at high luminance is one of the most important prerequisites towards practical application of any kind of light-emitting diode (LED). Herein, we report highly emissive organic fluorescent molecules based on phenanthroimidazole-benzothiadiazole derivatives capable of maintaining high external quantum efficiency (EQE) at high luminance enabled by triplet-triplet fusion (TTF) in doped organic LEDs. The PIBzP-, PIBzPCN-, and PIBzTPA-based devices showed EQEs of 8.27, 9.15, and 8.64 %, respectively, at luminance of higher than 1000 cd m -2 , with little efficiency roll-off., (© 2021 Wiley-VCH GmbH.)

Red emission is one of the three primary colors and is indispensable for full color displays. Fluorescent materials that can generate efficient red electroluminescence (EL) are limited and need to be developed. In this work, we report efficient red emitters based on phenanthro[9,10-d]imidazole-naphtho[2,3-c][1,2,5]thiadiazole donor-acceptor derivatives. The molecules, abbreviated as PINzP and PINzPCN, exhibited high photoluminescence quantum yield (PLQY) up to unity in doped films. They can also reach a relatively high PLQY of ∼30% in neat films. PINzP and PINzPCN were capable of generating efficient red EL in doped devices with a maximum external quantum efficiency (EQE) of 6.96% and 5.92%, respectively., (© 2021 Wiley-VCH GmbH.)

The gas pumping method (GP) holds the potential of outperforming the antisolvent method (AS) for fabricating perovskite solar cells (PSCs) in many ways such as free of toxic solvents, improved film uniformity, and device reproducibility. Most of the highest power conversion efficiencies (PCEs) of PSCs are still achieved by AS. Successful demonstrations of inverted PSCs produced by GP as well as the corresponding mechanisms are still lacking. Herein, we fabricate highly efficient inverted PSCs by GP delivering an overall efficiency of 21.54%, on par with that of the devices by AS (21.41%), and a superior reproducibility at the optimal film thickness. Nevertheless, as the perovskite film thickness increases, the PCE of GP devices slightly dropped while the AS devices decreased significantly. We found that the AS method tends to produce horizontal grain boundaries due to the heterogeneous solvent extraction while they can be effectively suppresed by the GP method.

Polybrominated diphenyl ethers (PBDEs), methoxylated PBDEs (MeO-PBDEs), and hydroxylated PBDEs (OH-PBDEs) are widely found in various environmental media, which is of concern given their biological toxicity. In this study, the phytotoxicities of BDE-47, 6-MeO-BDE-47, and 6-OH-BDE-47 to maize (Zea mays L.) were investigated by an in vivo exposure experiment. Results showed that BDE-47, 6-MeO-BDE-47, and 6-OH-BDE-47 inhibited seed germination and seedling development, and elevated malondialdehyde (MDA), carbonyl groups, and phosphorylated histone H2AX levels in maize roots, suggesting the inducement of lipid peroxidation, protein carbonylation, and DNA damage to maize. Exposure to BDE-47, 6-MeO-BDE-47, and 6-OH-BDE-47 caused the overproduction of H2O2, O2(•-), and •OH, and elevated the activities of antioxidant enzymes in the roots. In addition, 6-OH-BDE-47 caused more severe damage and reactive oxygen species (ROS) generation in maize than did BDE-47 and 6-MeO-BDE-47. These results demonstrated the phytotoxicities of BDE-47, 6-OH-BDE-47, and 6-MeO-BDE-47 to maize, and clarified that overproduction of ROS was the key mechanism leading to toxicity. This study offers useful information for a more comprehensive understanding of the environmental behaviors and toxicities of PBDEs, MeO-PBDEs, and OH-PBDEs.