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In-situ approach to fabricate BiOI photocathode with oxygen vacancies: Understanding the N2 reduced behavior in photoelectrochemical system
摘要： The adsorption and activation of N2 on the catalyst surface is a major problem in the process of photoelectrochemical (PEC) N2 reduction. Herein, we report a strategy to fabricate intrinsic BiOI (I-BiOI) photocathode with oxygen vacancies (OVs) (R-BiOI) by a facile in-situ method, and the R-BiOI was successfully selected as the model matrix for understanding the role of OVs in the PEC N2 reduction system for the first time. The correlation between carrier concentration/Lewis-base/active sites and OVs was in-depth demonstrated by Mott-Schottky plots and photoelectrochemical impedance spectroscopy (PEIS) results, meanwhile the Linear-sweep-voltammetry (LSV) data further confirmed the selectivity for active N2 over R-BiOI photocathode. The tandem built from BiVO4 photoanode and R-BiOI photocathode presented the desirable production rate of ammonia at about 1.4 mmol/m2/h, which is 1.3 and 2.9 times than that of I-BiOI (1.1 mmol/m2/h) and Pt (0.48 mmol/m2/h). Our findings have initially developed the proposed mechanism for the behavior of solar-electron-ammonia conversion and offered an alternative potential route for green N2 fixation.
关键词： Active sites,Lewis-base,Oxygen vacancies,BiOI,Photoelectrochemical (PEC) N2 fixation
更新于2025-09-23 15:23:52
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Exploring Lewis-Base Effects to Improve the Efficiency of [Co(bpy)3]2+/3+-Mediated Dye-Sensitized Solar Cells
摘要： The state-of-the-art cobalt(II/III) tris(bipyridyl) redox shuttles open a chapter for pursuing highly efficient dye-sensitized solar cells (DSSCs). Previous work has demonstrated that light exposure of the Co(III) along with the Lewis base additive, tert-butylpyridine (TBP) effectively improves the solar cell efficiency. With this as platform, a new Lewis base—tert-butylpyridine N-oxide (TBP-O) is introduced as an electrolyte co-additive instead of TBP alone. The resulting D35-sensitized solar cells exhibit an efficiency of 6.6% at full solar illumination, which further increases to 8.1% by exposing the new electrolyte mixture to the light and thus outperforms typical Li+-containing DSSCs. A mechanism with regard to the interactions between Co(III) and Lewis base additives supported by electrochemical and spectroscopic studies, is suggested to explain the performance improvement. The study illustrates negative effects of TBP on the charge- and mass-transfer kinetics at the electrode/electrolyte interface and reveals that the effects are eliminated by a light-induced reaction between Co(III) and TBP-O.
关键词： performance improvement,light exposure,dye-sensitized solar cells,Lewis base effects,cobalt electrolyte
更新于2025-09-23 15:21:01
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Characterizing Lewis Pairs Using Titration Coupled with In Situ Infrared Spectroscopy
摘要： Lewis acid-activation of carbonyl-containing substrates is a fundamental basis for facilitating transformations in organic chemistry. Historically, characterization of these interactions has been limited to models equivalent to stoichiometric reactions. Here, we report a method utilizing in situ infrared spectroscopy to probe the solution interactions between Lewis acids and carbonyls under synthetically relevant conditions. Using this method, we were able to identify 1:1 complexation between GaCl3 and acetone and a highly ligated complex for FeCl3 and acetone. The impact of this technique on mechanistic understanding is illustrated by application to the mechanism of Lewis acid-mediated carbonyl-olefin metathesis in which we were able to observe competitive binding interactions between substrate carbonyl and product carbonyl with the catalyst.
关键词： Lewis base,carbonyl,Lewis acid,infrared spectroscopy,titration,Issue 156,Chemistry,chemistry
更新于2025-09-19 17:13:59
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Novel Lewis Base Cyclam Self-Passivation of Perovskites without Anti-Solvent Process for Efficient Light-Emitting Diodes
摘要： Metal halide perovskites have been focused as a candidate applied as a promising luminescent material for next-generation high-quality lighting and high-definition display. However, as perovskite film formed, high density of defects would produce in solution processing inevitably, leading to low exciton recombination efficiency in light-emitting diodes (LEDs). Herein, a facile and novel self-passivation strategy to inhibit defects formation in perovskite film for constructing high performance LEDs is developed. For the first time, we introduce 1,4,8,11-tetraazacyclotetradecane (cyclam) in perovskite precursor solution and it spontaneously passivates defect states of CsPbBr3-based perovskite by coaction between amine and uncoordinated lead ions during spin-coating without anti-solvent process. Furthermore, as a delocalized system, cyclam also possesses chemical properties that facilitate exciton transportation. The proposed passivation strategy boosts the external quantum efficiency (EQE) from 1.25% (control device) to 16.24% (cyclam-passivated device). Further, defects passivation is also conductive to reduce LED degradation paths and improve device stability as the extrapolated lifetime (T50) of LEDs at an initial brightness of 100 cd/m2 is increased from 0.9 h to 127 h. These findings indicate the introduction of cyclam is highly effective to enhance the performance of LEDs, and such strategy in effectively reducing the defects could be also applied in other perovskite-based devices, such as lasers, solar cells, and photodetectors.
关键词： perovskites,self-passivation,light-emitting diodes,defect states,Lewis base cyclam
更新于2025-09-19 17:13:59
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Thioacetamide additive assisted crystallization of solution-processed perovskite films for high performance planar heterojunction solar cells
摘要： High-quality perovskite films with uniform coverage and large grains are indispensable to enhance the performance of perovskite solar cells with high efficiency and stability. However, solution-processed perovskite films usually possess small grains associated with abundant grain boundaries, which induce high trap state density and then seriously degrade the device performance. In this paper, the volatile Lewis base, thioacetamide (TAA), is employed as an additive to fabricate high-quality methylammonium lead iodide (MAPbI3) films. The average grain size of perovskite films increases continuously with increasing TAA content and reaches a maximum value of 960 nm in the sample with 1.0% TAA. However, the average gain size drops dramatically to the value of samples without TAA when TAA content increases to 2.0%, and then the average gain size keeps nearly unchanged upon further increasing TAA content up to 10%. This unusual grain size variation tendency is attributed to the volatility of additive, and a mechanism is proposed based on various characterizations to illustrate how volatile TAA improves perovskite film crystallization. Furthermore, the device based on the MAPbI3 film with 1.0% TAA shows a superior PCE of 18.9% and improved stability that the device with 1.0% TAA retains 88.9% of its initial performance after aging 816 h in the air with 25–35% relative humidity. The results strongly suggest that the TAA-modified MAPbI3 films as absorber layers can significantly enhance the performance of the perovskite solar cell due to large grains, high crystallization and reduced trap state density of the high quality TAA-modified MAPbI3 films.
关键词： Perovskite solar cells,Thioacetamide,Large grains,Lewis base,Thin film growth
更新于2025-09-19 17:13:59
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A universal approach for optimizing charge extraction in electron transporting layer-free organic solar cells <i>via</i> Lewis base doping
摘要： Although the improvement of power conversion efficiency (PCE) in organic photovoltaic cells (OSC) is due to the development of novel donors and non-fullerene acceptors, state-of-the-art devices commonly utilize charge transporting/extraction interlayers. Here we demonstrate a universal approach based on a series of tetraalkyl ammonium bromide (TXABr) Lewis bases as n-dopants for mediating electron extracting properties in a range of OSCs with non-fullerene or PCBM acceptors. Under optimal conditions, the TXABr-doped devices without electron transporting layers (ETLs) exhibit PCEs comparable to those of the ones based on a conventional device structure containing ETLs. We found that the doping efficiency of acceptors is intimately correlated with the chain length (Lchain) of dopants. In OSCs based on acceptors of ITIC derivatives (IT-4F, ITIC, ITM, and ITCC), similar Lchain-dependent doping efficiency and PCE modification are found, while for OSCs with acceptors bearing different structures in conjugated backbones or side chains, the selection rule of dopants to achieve the best performance enhancement is different. These correlations are explained by the mutual effects of electrostatic interaction in the dopants and steric hindrance between the dopants and acceptors, the latter of which is affected by the compatibility of side chains in the host and dopant. With TXABr doping, (quasi-)ohmic contacts for electrons are realized in these ETL-free devices, leading to expediting the charge sweepout with mitigated interfacial charge recombination. This work offers a promising pathway to realize high efficiency non-fullerene OSCs with simplified device architecture.
关键词： organic solar cells,power conversion efficiency,charge extraction,Lewis base doping,electron transporting layer-free
更新于2025-09-16 10:30:52
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Efficient and stable tin-based perovskite solar cells by introducing π-conjugated Lewis base
摘要： Tin-based perovskite solar cells (TPSCs) as the most promising candidate for lead-free PSCs have incurred extensive researches all over the world. However, the crystallization process of tin-based perovskite is too fast during the solution-deposited process, resulting in abundant pinholes and poor homogeneity that cause serious charge recombination in perovskite layer. Here, we employed the π-conjugated Lewis base molecules with high electron density to systematically control the crystallization rate of FASnI3 perovskite by forming stable intermediate phase with the Sn-I frameworks, leading to a compact and uniform perovskite film with large increase in the carrier lifetime. Meanwhile, the introduction of the π-conjugated systems also retards the permeation of moisture into perovskite crystal, which significantly suppresses the film degradation in air. These benefits contributed to a stabilizing power conversion efficiency (PCE) of 10.1% for the TPSCs and maintained over 90% of its initial PCE after 1000-h light soaking in air. Also, a steady-state efficiency of 9.2% was certified at the accredited test center.
关键词： FASnI3 perovskite,π-conjugated Lewis base,perovskite solar cells,power conversion efficiency,crystallization rate
更新于2025-09-12 10:27:22
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Improved Performance of Carbon Electrode Perovskite Solar Cells using Urea Treatment in Two Step Processing
摘要： Perovskite solar cell has made a steadily research progress with superior photovoltaic power conversion efficiency (PCE) over 25%. The quality of perovskite film is a key factor affecting device efficiency. Lewis bases such as urea, DMSO and thiourea etc. have been applied in perovskite precursor solutions for one-step processing to effectively control film morphology. Herein, we report urea treatment in a two-step processing for obtaining high quality methylammonium lead triiodide perovskite (CH3NH3PbI3) film. This is accomplished by immersing the PbI2 film into the mixture solution of urea/methylammonium iodide (MAI). The optimized urea concentration in the MAI solution is 0.4 mg/mL, attributing to larger-sized and better crystalline perovskite grains than that without urea additive. The main function of the urea additive is the formation of the adduct MAI·PbI2·O=C(NH2)2, retarding the crystallization process of the perovskite film. The steady-state and time-resolved photoluminescence measurements revealed that perovskite CH3NH3PbI3 grown using the optimized concentration of urea prolonged carrier lifetime and reduced carrier recombination. Finally, the carbon-based perovskite solar cells fabricated from the optimal urea concentration of 0.4 mg/mL achieved the enhanced photovoltaic performance with the highest PCE of 13.10% and an average value of 11.34%, in comparison to devices without urea treatment exhibiting an average PCE of only 8.67%.
关键词： Lewis base additive,grain size,carbon-based perovskite solar cell,urea
更新于2025-09-12 10:27:22
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Interface Engineering in Hybrid Iodide CH <sub/>3</sub> NH <sub/>3</sub> PbI <sub/>3</sub> Perovskites Using Lewis Base and Graphene toward High-Performance Solar Cells
摘要： Photovoltaic solar cells based on organic-inorganic hybrid halide perovskites have achieved a substantial breakthrough via advanced interface engineerings. Reports have emphasized that combining the hybrid perovskites with Lewis base and/or graphene can definitely improve the performance through surface trap passivation and band alignment alteration; the underlying mechanisms are not yet fully understood. Here, using density functional theory calculations, we show that upon the formation of CH3NH3PbI3 interfaces with three different Lewis base molecules and graphene, the binding strength with S -donors thiocarbamide and thioacetamide is higher than with O-donor dimethyl sulfoxide, while the interface dipole and work function reduction tend to increase from S -donors to O-donor. We provide evidences of deep trap states elimination in the S -donor perovskite interfaces through the analysis of defect formation on the CH3NH3PbI3(110) surface, and of stability enhancement by estimation of activation barriers for vacancy-mediated iodine atom migrations. These theoretical predictions are in line with the experimental observation of performance enhancement in the perovskites prepared using thiocarbamide.
关键词： Perovskite solar cells,ion diffusion,defect,Lewis base,work function,graphene
更新于2025-09-11 14:15:04
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Two Series of Microporous Lanthanide–Organic Frameworks with Different Secondary Building Units and Exposed Lewis Base Active Sites: Sensing, Dye Adsorption, and Magnetic Properties
摘要： Two series of new lanthanide complexes, {[Ln(L)1.5(H2O)]·DMA·4H2O}n (1-Ln, Ln = Tb, Gd, and Dy) and {[La2(L)3]·4H2O}n (2-La), were prepared successfully by Ln3+ ions and a N-heterocyclic dicarboxylic (2-pyrimidin-5-yl)terephthalic acid (H2L) ligand. The four complexes are three-dimensional (3D) microporous frameworks with different secondary building units (SBUs) and exposed Lewis base active sites. Topology analyses reveal that 1-Ln are the binodal (3,8)-connected tfz-d (43)2(46·618·84) nets and 2-La is a binodal (2,12)-connected (4)6(46·848·1212) net. The photoluminescence of 1-Tb, the dye adsorption of 1-Tb and 2-La, and the magnetism of 1-Dy have been well studied. The luminescent explorations indicate that 1-Tb is a highly efficient probe for sensing Fe3+ and Cr2O72?, respectively. Complexes 1-Tb and 2-La display the unique selective adsorption to Congo red (CR) dyes. Magnetic measurements further indicate that 1-Dy has a slow magnetic relaxation performance.
关键词： lanthanide complexes,dye adsorption,magnetism,photoluminescence,microporous frameworks,Lewis base active sites
更新于2025-09-04 15:30:14