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Photoinduced carriers recombine almost twice slower and diffuse 20% faster in the disordered, β-phased samples than in the ordered, γ-phased ones.

Lead halide perovskite solar cells (PSCs) have achieved great progress and become one of the most promising candidates for next-generation low-cost and high-efficiency photovoltaics (PVs). There ar...

Achieving reduced defect density and efficient charge carrier extraction plays a vital role for efficient and stable perovskite solar cells (PSCs). Over the course of technical development, it is desired to use one single material or approach to synergistically passivate defects and enhance the charge extraction. In this work, we developed an effective strategy for obtaining efficient and stable PSCs via incorporating quasi-monolayer two-dimensional WSe2 into the MAPbI3 perovskite layer. The addition of WSe2 helps with the formation of perovskite film with higher quality and also passivates the Pb-related defects through Pb-Se coordination bonding. MAPbI3/WSe2 shows a more matched energy-level alignment between the perovskite layer and hole transport layer for accelerated hole extraction. Consequently, the performances of PSCs significantly improved with power conversion efficiency increase from 19.2% to 21.2% after the incorporation of WSe2. Accordingly, the MAPbI3/WSe2-based PSCs exhibit well-improved photostability with suppression of Pb0 defect formation.

Sequential Cs incorporation strategy is developed to decouple crystallization of FACs perovskite with reduced electron-phonon coupling, resulting in highly stable FACs tri-iodide perovskite photovoltaics with record efficiency. Although pure formamidinium iodide perovskite (FAPbI(3)) possesses an optimal gap for photovoltaics, their poor phase stability limits the long-term operational stability of the devices. A promising approach to enhance their phase stability is to incorporate cesium into FAPbI(3). However, state-of-the-art formamidinium-cesium (FA-Cs) iodide perovskites demonstrate much worse efficiency compared with FAPbI(3), limited by the different crystallization dynamics of formamidinium and cesium, which result in poor composition homogeneity and high trap densities. We develop a novel strategy of crystallization decoupling processes of formamidinium and cesium via a sequential cesium incorporation approach. As such, we obtain highly reproducible, highly efficient and stable solar cells based on FA(1)(-)(x)Cs(x)PbI(3) (x = 0.05-0.16) films with uniform composition distribution in the nanoscale and low defect densities. We also revealed a new stabilization mechanism for Cs doping to stabilize FAPbI(3), i.e. the incorporation of Cs into FAPbI(3) significantly reduces the electron-phonon coupling strength to suppress ionic migration, thereby improving the stability of FA-Cs-based devices. Funding Agencies|National Natural Science Foundation of China [22025505]; Program of Shanghai Academic/Technology Research Leader [20XD1422200]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]

Black-phase formamidinium lead iodide (FAPbI

The chemical instability of metal halide perovskite materials can be ascribed to their unique properties of softness, in which the chemical bonding between metal halide octahedral frameworks and cations is the weak ionic and hydrogen bonding as in most perovskite structures. Therefore, various strategies have been developed to stabilize the cations and metal halide frameworks, which include incorporating additives, developing two-dimensional perovskites and perovskite nanocrystals, etc. Recently, the important role of utilizing steric hindrance for stabilizing and passivating perovskites has been demonstrated. In this perspective, we summarize the applications of steric hindrance in manipulating and stabilizing perovskites. We will also discuss how steric hindrance influences the fundamental kinetics of perovskite crystallization and film formation processes. The similarities and differences of the steric hindrance between perovskite solar cells and perovskite light emission diodes are also discussed. In all, utilizing steric hindrance is a promising strategy to manipulate and stabilize metal halide perovskites for optoelectronics., Manipulation on steric hindrance can influence the fundamental kinetics of perovskite crystallization and film formation, therefore stabilizing and passivating perovskite structures, and promoting the commercialization of stable perovskite devices.

The in-situ formation of reduced dimensional perovskite layer via post-synthesis ion exchange has been an effective way of passivating organic-inorganic hybrid perovskites. In contrast, cesium ions in Cs based inorganic perovskite with strong ionic binding energy cannot exchange with those well-known organic cations to form reduced dimensional perovskite. Herein, we demonstrate that tetrabutylammonium (TBA + ) cation can intercalate into CsPbI 3 to effectively substitute the Cs cation to form one-dimensional (1D) TBAPbI 3 layer in the post-synthesis TBAI treatment. Such TBA cation intercalation leads to in-situ formation of TBAPbI 3 protective layer to heal defects at surface of inorganic CsPbI 3 perovskite. The TBAPbI 3 -CsPbI 3 perovskite exhibited enhanced stability and lower defect density, and the corresponding perovskite solar cell devices achieved an improved efficiency up to 18.32% compared to the control one's efficiency of 15.85%. Our findings would inspire further investigation and development of reduced dimensional perovskite protection strategy for inorganic perovskites.

The simultaneous improvement of photovoltaic performance and stability is crucial for further commercial development of MAPbI3 perovskites. Here we report a dual-ion exchange and alloying method using DMACl (dimethylammonium chloride) to improve the stability and charge transport ability. The synergetic effect of the DMA cation and Cl anion induces the re-growth of perovskite crystals and forms cubic phase MA1−xDMAxPbI3. As a result, the efficiency and stability of DMACl-based MAPbI3 perovskite solar cells are significantly improved. Such dual-function of DMA cation doping and the Cl anion additive provides an effective strategy for the control of MAPbI3 perovskite crystallization.

5-Ammonium valeric acid iodide (AVAI) has been widely known as a stabilizer to enhance the stability of MAPbI3 perovskite, but its role and function is still under exploration. The typical 2D perovskites of AVA2PbI4 have been proposed as the capping layer for stabilization. Here, a novel AVA-MA mixed-cation perovskite of AVAMAPbI4 is found to show a more even and compact coverage than the typical 2D perovskite of AVA2PbI4. A simple post-treatment on MAPbI3 films by using AVAI isopropanol solution can fabricate such a mixed-cation 2D perovskite capping layer on the MAPbI3 sample. This AVAMAPbI4 capping layer effectively passivates surface defects of MAPbI3 perovskite films and reduces the charge-carrier recombination, enabling AVAI-MAPbI3 perovskite films to exhibit improved stability against thermal and moisture stress. Finally, the AVAI-MAPbI3-based perovskite solar cells also show an enhanced photovoltaic performance with a champion PCE up to 20.05% with enhanced stability.

Lead halide perovskites have been widely studied for successful photovoltaic applications because of their exceptional optoelectronic properties, high photoconversion efficiencies, facile solution process and low cost. However, both organic–inorganic hybrid perovskite and all-inorganic perovskite solar cells still face the challenges with respect to higher photovoltaic performances and long-term stabilities against various environmental factors. To address these stability issues, solution-processed colloidal perovskite nanocrystals have been introduced into perovskite solar cells either as the sole light absorber material, or a surface additive for bulk perovskite films. The incorporation of perovskite quantum dots onto bulk perovskite thin films has shown great potential on improving the band alignment in solar cell structures, passivating bulk and surface defects, and enhancing overall device performances. Here in this perspective, we summarize the recent development on integrating semiconductor nanocrystals, including perovskite and metal chalcogenide quantum dots, onto bulk perovskite thin films for solar cell device fabrication. We also highlight and provide an outlook of the ongoing research studies regarding how the function and mechanism of this nanocrystal incorporation, the distribution of the added components, as well as the processing route, the chemical composition and the morphology of the nanocrystal can affect the fabricated device performances.

A broad-based interlaboratory study of glycosylation profiles of a reference and modified IgG antibody involving 103 reports from 76 laboratories., Graphical Abstract Highlights A broad-based interlaboratory study of the glycosylation of a reference antibody: NISTmAb. 103 reports were received from 76 diverse laboratories worldwide. Analysis involved two samples, the NISTmAb and an enzymatically modified sample, enabling within-lab separation of random and systematic errors using the “Youden two-sample” method. Consensus values were derived and similar performance across all experimental methods was noted., Glycosylation is a topic of intense current interest in the development of biopharmaceuticals because it is related to drug safety and efficacy. This work describes results of an interlaboratory study on the glycosylation of the Primary Sample (PS) of NISTmAb, a monoclonal antibody reference material. Seventy-six laboratories from industry, university, research, government, and hospital sectors in Europe, North America, Asia, and Australia submitted a total of 103 reports on glycan distributions. The principal objective of this study was to report and compare results for the full range of analytical methods presently used in the glycosylation analysis of mAbs. Therefore, participation was unrestricted, with laboratories choosing their own measurement techniques. Protein glycosylation was determined in various ways, including at the level of intact mAb, protein fragments, glycopeptides, or released glycans, using a wide variety of methods for derivatization, separation, identification, and quantification. Consequently, the diversity of results was enormous, with the number of glycan compositions identified by each laboratory ranging from 4 to 48. In total, one hundred sixteen glycan compositions were reported, of which 57 compositions could be assigned consensus abundance values. These consensus medians provide community-derived values for NISTmAb PS. Agreement with the consensus medians did not depend on the specific method or laboratory type. The study provides a view of the current state-of-the-art for biologic glycosylation measurement and suggests a clear need for harmonization of glycosylation analysis methods.

Upcycling plastic waste pollution for sustainable resources and energy is an ideal solution to plastic waste-related environmental issues. Polyethylene terephthalate (PET), one of the most prominent single-use daily plastics with up to millions of tons produced annually, has recently been explored with respect to chemical recycling to ameliorate its environmental impact. In this work, we report an electrochemical upcycling approach to electrocatalytic oxidation of PET hydrolysate using Cu-based nanowire catalysts. We demonstrate that the electrocatalyst can catalyze the ethylene glycol (EG) molecule derived from PET waste toward formate with high selectivity and exhibit a lower onset potential for EG oxidation than for water oxidation. Experimental and density functional theory calculation results reveal that the oxidation pathway of EG on CuO can selectively break the C-C bond to generate formic acid. This work sheds light on employing earth-abundant metal catalysts to convert PET plastic waste to produce valued chemicals and green hydrogen.

Although pure formamidinium iodide perovskite (FAPbI3) possesses an optimal gap for photovoltaics, their poor phase stability limits the long-term operational stability of the devices. A promising approach to enhance their phase stability is to incorporate cesium into FAPbI3. However, state-of-the-art formamidinium-cesium (FA-Cs) iodide perovskites demonstrate much worse efficiency compared with FAPbI3, limited by different crystallization dynamics of formamidinium and cesium, which result in poor composition homogeneity and high trap densities. We develop a novel strategy of crystallization decoupling processes of formamidinium and cesium via a sequential cesium incorporation approach. As such, we obtain highly reproducible and highly efficient solar cells based on FA1-xCsxPbI3 films, with uniform composition distribution and low defect densities. In addition, our cesium-incorporated perovskites demonstrate much enhanced stability compared with FAPbI3, as a result of suppressed ionic migration due to reduced electron-phonon coupling.

All-inorganic perovskites with comparable optoelectronic properties but improved intrinsic stability to organic-inorganic hybrid perovskites have attracted increasing amount of attention over years for applicational advances in perovskite solar cells (PSCs) and various optoelectronics including light-emitting devices (LEDs). Cesium lead halide perovskites of tunable I/Br ratio that possess bandgap aligning with the sunlight region are promising candidates for PSC. As impressive progress has been made on fabrication methods with device efficiency improved from the initial 2.9% with low phase stability to over 20% with high stability, there still are many on-going discussions regarding the perovskite crystal growth mechanism, especially at low temperatures with the assistance of external factors. In this review, we summary recent developments of using organic matrix, including the addition and usage of organic ions, polymers and solvent molecules to achieve the crystallization of black phase inorganic perovskites at temperatures lower than the phase transition point. Secondly, we discuss the possible mechanisms of this low-temperature crystallization and their effects on the stability of black phase perovskites. In the end, we outlook and perspective a more comprehensive understanding that can help with further development of fabricating large-scale inorganic perovskite for optoelectronic applications.

This paper presents a survey and implementation of BERT language models by analyzing and summarizing its superiority or limitations in relevant tasks and the reasons for it. On this basis, a family of BERT-like models is collected to address these limitations - namely, ERNIE 2.0 (Baidu) by adding and refining pre-training tasks and MT-DNN (MICROSOFT) by introducing multi-task learning downstream. By comparing the changes in the native models with controlling variables for specific tasks and the impact of pre-training on the models in real-world applications with the same language model architecture, we summarize and outlook the potential directions and characteristics of future technological iterations in the field of natural language processing in language modeling.

Inorganic CsPbI

ConspectusOwing to the remarkable progress achieved over the past decade with research efforts from the perspectives of material synthesis, device configuration, and theoretical investigation, metal halide perovskites have emerged as a revolutionary class of light-absorbing semiconductors. The perovskite photovoltaic devices have demonstrated an impressive increase in power conversion efficiency. For single-junction perovskite solar cells, the value has risen from the initial one-digit maximum to the state-of-art record of 25.5%. Among various chemical and structural variations of perovskites, inorganic lead halides possess a more favorable operational stability and hold greater potential for perovskite/silicon tandem photovoltaics' top cells. At the initial stage of exploring all-inorganic perovskites for optoelectronic applications, many concepts, technical routes, and modification strategies were directly adopted from research on the more-developed field of organic-inorganic hybrid perovskite (OIHP). However, as understandings on inorganic perovskite deepen with research experience gained from both experimental and theoretical progression, it has been found that the difference between the asymmetric, volatile organic cations and the spherical, stable inorganic cations can lead to drastic changes on overall material properties and the subsequent device performances. In detail, the disparities reflect the crystalline and phase profiles of the material, the fabrication and passivation rationales of perovskite thin films, and the photophysics in the assembled optoelectronic devices. Therefore, the discussions of all-inorganic perovskites have their own exclusivity and are worthy of a specialized scrutinization.Here in this Account, the latest progress on the stabilization of inorganic lead halide perovskites for efficient photovoltaic applications is highlighted. A library of chemical compositions will be discussed with a focus on notable works about CsPbI3, which possesses a more favorable bandgap as a tandem to commercialized silicon solar cells. To underscore the influence of the crystal phase on the stability of inorganic perovskites, fundamental investigations regarding the chemical and physical properties, including experimental and theoretical studies, will be summarized as a means of phase control. The stability of inorganic lead halide perovskites can also be improved by the strategic introduction of external components to the light-absorbing layer, such as the incorporation of inorganic halides, organic cations, OIHPs with low dimension, etc. These strategies can synergistically improve the stability and efficiency of the fabricated devices from the perspectives of compositional tuning, dimensional engineering, surface termination, and low-dimension capping. On the basis of a careful examination and an analysis of works achieved in these categories from our group and others, we will then discuss some promising approaches toward achieving more stable and efficient photovoltaics using inorganic lead halide perovskites.

Recently, lead halide perovskite solar cells have become a promising next-generation photovoltaics candidate for large-scale application to realize low-cost renewable electricity generation. Although perovskite solar cells have tremendous advantages such as high photovoltaic performance, low cost and facile solution-based fabrication, the issues involving lead could be one of the main obstacles for its commercialization and large-scale applications. Lead has been widely used in photovoltaics industry, yielding its environmental and health issues of vital importance because of the widespread application of photovoltaics. When the solar cell panels especially perovskite solar cells are damaged, lead would possibly leak into the surrounding environment, causing air, soil and groundwater contamination. Therefore, lots of research efforts have been put into evaluating the lead toxicity and potential leakage issues, as well as studying the encapsulation of lead to deal with leakage issue during fire hazard and precipitation in photovoltaics. In this review, we summarize the latest progress on investigating the lead safety issue on photovoltaics, especially lead halide perovskite solar cells, and the corresponding solutions. We also outlook the future development towards solving the lead safety issues from different aspects.

Defect-triggered phase degradation is generally considered as the main issue that causes phase instability and limited device performance for CsPbI

Achieving reduced defect density and efficient charge carrier extraction plays a vital role for efficient and stable perovskite solar cells (PSCs). Over the course of technical development, it is desired to use one single material or approach to synergistically passivate defects and enhance the charge extraction. In this work, we developed an effective strategy for obtaining efficient and stable PSCs via incorporating quasi-monolayer two-dimensional WSe

The relationship between phosphonic acid (PA) binding strength, surface coverage, and quantum rod or dot aspect ratio was studied. Seven nanocrystals with an aspect ratio (l/w) between 1.0 and 11.7, including five CdSe with l/w between 1.0 and 5.2 and two CdSe/CdS with dot-in-rod and rod-in-rod microstructures with l/w between 7.5 and 11.7, were synthesized. The nature of phosphonic acid binding was studied in situ using one-dimensional 1H nuclear magnetic resonance (NMR) spectroscopy as well as two-dimensional diffusion ordered spectroscopy (DOSY) and relaxation ordered spectroscopy (ROSY). The DOSY results were used to separate strongly binding phosphonic acid signatures from weakly binding ones, thus allowing for estimates of ligand densities (LDs) to be calculated, which showed a significant drop from LD = 2.21 nm–2 for spherical CdSe with l/w = 1.0 to LD = 0.23 nm–2 for CdSe/CdS with l/w = 11.7. Interestingly, intermediate l/w = 1.7 showed a higher LD of 4.81 nm–2. The results suggest a wrapping or relatively flat binding by phosphonic acids on the sides of the rods, leading to decent surface coverage for low aspect ratios but lower LD for more elongated rods. This model was further confirmed using ROSY, which revealed similar relaxation times (T1) for each proton of the phosphonic acids on the rods, indicating similar ligand–quantum rod (QR) interface.

The in situ formation of reduced dimensional perovskite layer via post-synthesis ion exchange has been an effective way of passivating organic-inorganic hybrid perovskites. In contrast, cesium ions in Cs-based inorganic perovskite with strong ionic binding energy cannot exchange with those well-known organic cations to form reduced dimensional perovskite. Herein, we demonstrate that tetrabutylammonium (TBA

Low-bandgap formamidinium-cesium (FA-Cs) perovskites of FA 1- x Cs x PbI 3 ( x < 0.1 ) are promising candidates for efficient and robust perovskite solar cells, but their black-phase crystallization is very sensitive to annealing temperature. Unfortunately, the low heat conductivity of the glass substrate builds up a temperature gradient within from bottom to top and makes the initial annealing temperature of the perovskite film lower than the black-phase crystallization point (~150°C). Herein, we take advantage of such temperature gradient for the diffusional growth of high-quality FA-Cs perovskites by introducing a thermally unstable MA + cation, which would firstly form α -phase FA-MA-Cs mixed perovskites with low formation energy at the hot bottom of the perovskite films in the early annealing stage. The natural gradient annealing temperature and the thermally unstable MA + cation then lead to the bottom-to-top diffusional growth of highly orientated α -phase FA-Cs perovskite, which exhibits 10-fold of enhanced crystallinity and reduced trap density ( ~ 3.85 × 10 15 c m − 3 ). Eventually, such FA-Cs perovskite films were fabricated into stable solar cell devices with champion efficiency up to 23.11%, among the highest efficiency of MA-free perovskite solar cells.

A ~20 nm thick compact TiO2 was deposited on patterned FTO (TEC-7) by spray pyrolysis of 0.2 M Ti (IV) bis(ethylacetoacetate)-diisopropoxide 1-butanol solution at 450 ºC followed by annealing at 450 ºC for one hour. The perovskite precursor solution was prepared by dissolving CsI, FAI, PbI2 and DMAI in 1 mL DMF and was deposited on 70 ℃ preheated c-TiO2/FTO substrate by spin coating at 3000 rpm for 30 s. The obtained precursor film was annealed at 170℃ for 40 min. A hole-transport material (HTM) solution containing 0.1 M spiro-OMeTAD, 0.035 M Li-TFSi, and 0.12 M 4-tert-butylpyridine (tBP) in chlorobenzene solution was then spin coated onto the perovskite film at 4000 rpm for 20 s. Finally, a 100 nm thick Ag was deposited as contact layer via thermal evaporator.

Research on chemically stable inorganic perovskites has achieved rapid progress in terms of high efficiency exceeding 19% and high thermal stabilities, making it one of the most promising candidates for thermodynamically stable and high-efficiency perovskite solar cells. Among those inorganic perovskites, CsPbI

Inorganic CsPbI3 perovskite with high chemical stability is attractive for efficient deep-red perovskite light-emitting diodes (PeLEDs) with high color purity. Compared to PeLEDs based on ex-situ-synthesized CsPbI3 nanocrystals/quantum dots suffering from low conductivity and efficiency droop under high current densities, in situ deposited 3D CsPbI3 films from precursor solutions can maintain high conductivity but show high trap density. Here, it is demonstrated that introducing diammonium iodide can increase the size of colloids in the precursor solution, retard the phase-transition rate, and passivate trap states of the in-situ-formed cuboid crystallites. The PeLED based on the one-step-formed 3D CsPbI3 cuboid crystallite films shows a peak external quantum efficiency (EQE) value up to 15.03% because of the high conductivity and reduced trap states. Furthermore, this one-step method also has a wide processing window, which is attractive for flow-line production of large-area PeLED modules. The fabrication of a 9 cm2 PeLED that exhibits a peak EQE of 10.30% is successfully demonstrated.

Defect-triggered phase degradation is generally considered as the main issue that causes phase instability and limited device performance for CsPbI3 inorganic perovskites. Here, a defect compensation in CsPbI3 perovskite through crystal secondary growth of inorganic perovskites is demonstrated, and highly efficient inorganic photovoltaics are realized. This secondary growth is achieved by a solid-state reaction between a bromine salt and defective CsPbI3 perovskite. Upon solid-state reaction, the Br- ions can diffuse over the entire CsPbI3 perovskite layer to heal the undercoordinated Pb2+ and conduct certain solid-state I/Br ion exchange reaction, while the organic cations can potentially heal the Cs+ cation vacancies through coupling with [PbI6 ]4- octahedra. The carrier dynamics confirm that this crystal secondary growth can realize defect compensation in CsPbI3 . The as-achieved defect-compensated CsPbI3 not only improves the charge dynamics but also enhances the photoactive phase stability. Finally, the CsPbI3 -based solar cell delivers 20.04% efficiency with excellent operational stability. Overall, this work proposes a novel concept of defect compensation in inorganic perovskites through crystal secondary growth induced by solid-state reaction that is promising for various optoelectronic applications.

High cell density is an important factor in achieving high bioreactor productivity. To meet the oxygen demand with density at >100 × 106 cells/mL, a frit sparger is often used. In this study, the impact of Pluronic® F68 on a perfusion process using a frit sparger was studied. The perfusion process was developed using an alternating tangential flow device with a 0.2 µm PES hollow fiber filter. Pluronic® F68 at 2 g/L was sufficient in preventing cell damage at gas flow rate of ~0.20 vvm from a drilled hole sparger (0.5 mm) but inadequate at ~0.025 vvm from a frit sparger (20 µm). Increase of Pluronic® F68 concentration to 5 g/L prevented cell death at up to ~0.10 vvm from the frit sparger and was able to maintain high cell density at high viability in the range of 60–80 × 106 cells/mL. Such positive effect was demonstrated in both 3- and 200-L bioreactors. Supplementing additional Pluronic® F68 was also effective in restoring cell growth/viability from low viability cultures. Increased Pluronic® F68 concentration had no adverse impact on target antibody, HCP, and Pluronic® F68 transmissions.