Molecular Dipole Engineering of Carbonyl Additives for Efficient and Stable Perovskite Solar Cells.

Carbonyl functional materials as additives are extensively applied to reduce the defects density of the perovskite film. However, there is still a lack of comprehensive understanding for the effect of carbonyl additives to improve device performance. In this work, we systematically study the effect of carbonyl additive molecules on the passivation of defects in perovskite films. After a comprehensive investigation, the results confirm the importance of molecular dipole in amplifying the passivation effect of additive molecules. The additive with strong molecular dipole possesses the advantages of enhancing the efficiency and stability of perovskite solar cells (PSCs). After optimization, the companion efficiency of PSCs is 23.20 %, and it can maintain long-term stability under harsh conditions. Additionally, a large-area solar cell module-modified DLBA was 20.18 % (14 cm2 ). This work provides an important reference for the selection and designing of efficient carbonyl additives.

Deeper Insight into the Role of Organic Ammonium Cations in Reducing Surface Defects of the Perovskite Film.

Organic ammonium salts (OASs) have been widely used to passivate perovskite defects. The passivation mechanism is usually attributed to coordination of OASs with unpaired lead or halide ions, yet ignoring their interaction with excess PbI2 on the perovskite film. Herein, we demonstrate that OASs not only passivate defects by themselves, but also redistribute excess aggregated PbI2 into a discontinuous layer, augmenting its passivation effect. Moreover, alkyl OAS is more powerful to disperse PbI2 than a F-containing one, leading to better passivation and device efficiency because F atoms restrict the intercalation of OAS into PbI2 layers. Inspired by this mechanism, exfoliated PbI2 nanosheets are adopted to provide better dispersity of PbI2 , further boosting the efficiency to 23.14 %. Our finding offers a distinctive understanding of the role of OASs in reducing perovskite defects, and a route to choosing an OAS passivator by considering substitution effects rather than by trial and error.

In-Situ Immobilization of Cd-Contaminated Soils Using Ferronickel Slag as Potential Soil Amendment.

The current study investigated the efficiency and mechanisms of in situ immobilization of artificially Cd-contaminated soils with ferronickel slag (FNS). The available Cd content of soil was measured and the modified European Community Bureau of Reference (BCR) sequential extraction procedure (SEP) was adopted to quantify the evolutions of Cd chemical speciation after the immobilization by the FNS. The results showed that the addition of FNS (5%‒15%) remarkably reduced the available Cd content and increased the pH and cation exchange capacity of soils. The passivation rate of Cd increased from 58.13% to 73.25% as the spiked Cd content rose from 10 to 120 mg kg‒1. The BCR SEP test revealed that the FNS addition substantially reduced the acid soluble fraction and increased the residual fraction of Cd, indicating the reduction of mobility and bioavailability of Cd in soils. The chemical precipitation, ion exchange and surface complexation might be involved in in situ immobilization of Cd-contaminated soils by the FNS.

Optimization of a Solution-Processed TiOx/(n)c-Si Electron-Selective Interface by Pre- and Postdeposition Treatments.

Developing a vacuum-free and low-temperature deposition technique for dopant-free carrier-selective materials without sacrificing their performance can reduce the fabrication cost and CO2 footprint of silicon heterojunction (SHJ) solar cells. In this contribution, to activate the full capacity of the solution-processed TiOx as an electron-selective passivation contact, the effects of various pre- and postdeposition treatments on the passivation quality and contact resistivity are investigated simultaneously. It is demonstrated that the electrical properties of a thin TiOx layer spin-coated on an n-type silicon substrate can be remarkably improved through tailor-made pre- and postdeposition treatments. A notable low surface recombination velocity (SRV) of 6.54 cm/s and a high implied open-circuit voltage (iVoc) of 706 mV are achieved. In addition, by inserting a 1 nm LiFx buffer layer between TiOx and Al metal contact, a low contact resistivity (ρc) of 15.4 mΩ·cm2 is extracted at the n-Si/SiOx/TiOx heterojunction. Our results bring the solution-processed TiOx electrical properties to a level on par with those of state-of-the-art pure TiOx layers deposited by other techniques. Chemical and electrical characterizations elucidate that the improved electrical properties of the investigated Si/SiOx/TiOx heterojunction are mediated by the concomitant involvement of chemical and field-effect passivation.

Study on the Water-Sensitivity Passivation Effect and Mechanism of PA-ES Composite Materials.

The water-sensitive effect of expansive soil (ES) poses a serious challenge to the safety and durability of infrastructure. To reduce the effect of water sensitivity on expansive soil, a new powder soil passivator with polyacrylic (PA) as the main component was proposed. In this paper, a series of macroscopic and microscopic tests were conducted to evaluate the water-sensitive passivation effect and mechanism of PA-ES composites. The results showed that PA significantly attenuated the water sensitivity of ES. With the increase in PA content in the PA-ES composites, the water sensitivity of the composites decreased, swelling and shrinkage deformation decreased, and the strength of the composites increased significantly. In addition, when the content of PA in the PA-ES composite is 6%, it can significantly alleviate the deformation of the composite and improve the saturated shear strength of the composite, meeting the requirements of ES engineering disposal. Finally, the results show that the mechanism of PA passivation of ES water-sensitive effect mainly includes adsorption, binding, and filling. The study shows that PA has a broad engineering application prospect as an ES passivator.

Understanding the cadmium passivation and nitrogen mineralization of aminated lignin in soil.

Aminated lignin (AL) was prepared and first applied to remediation of cadmium (Cd) pollution in soil. Meanwhile, the nitrogen mineralization characteristics of AL in soil and its effect on soil physicochemical properties were elucidated by soil incubation experiment. The results showed that the Cd availability was dramatically lowered in soil by adding the AL. The DTPA-extractable Cd content of AL treatments was considerably reduced by 40.7-71.4 %. The soil pH (5.77-7.01) and absolute value of zeta potential (30.7-34.7 mV) enhanced simultaneously as the AL additions increased. The content of soil organic matter (SOM) (99.0-264.0 %) and total nitrogen (95.9-301.3 %) were gradually enhanced due to high C (63.31 %) and N (9.69 %) content in AL. Moreover, AL significantly elevated the content of mineral nitrogen (77.2-142.4 %) and available nitrogen (95.5-301.7 %). The first-order kinetic equation of soil nitrogen mineralization revealed that AL greatly enhanced nitrogen mineralization potential (84.7-143.9 %) and reduced environmental pollution by lowering the loss of soil inorganic nitrogen. AL could effectively reduce the availability of Cd through direct (self-adsorption) and indirect effects (improvement of soil pH, SOM and reduction of soil zeta potential), thereby achieving passivation of Cd in soil. In short, this work will develop a novel approach and technical support for soil heavy metal remediation, which is of great significance for improving the sustainable development of agricultural production.

Efficient and safe use of a slow-release Mn material for three sequential crops of rice in Cd-contaminated paddy soils.

Traditional passivators reduce the effectiveness of Cd by ion exchange, chemisorption, and complexation in soil. However, traditional passivators have defects such as easy aging and poor durability, which not only reduce the treatment efficiency but also increase the risk of primary soil environmental pollution. For this reason, considering that Mn and Cd have physiological antagonism in rice, sepiolite-supported manganese ferrite (SMF) was prepared in this study to improve passivation persistence. The passivation mechanism, effect and duration of SMF were explored. The results showed that SMF has a dense and small pore structure and that the surface is rough, which provides abundant adsorption sites for Cd2+ adsorption. When the SMF adsorbs Cd2+, ions or functional groups in the material, such as MnOOH*, will exchange with Cd2+ to form Cd(OH)2 and other internal complexes. Indoor pure soil cultivation experiments showed that 0.1 % SMF can reduce the effective Cd content of soil by 41.32 %, demonstrating the efficiency of SMF. The three-crop rice experiments in pots showed that SMF could increase soil pH and continuously increase the content of available Mn in soil. Increasing the content of available Mn reduces the ability of rice to absorb Cd. In addition, the three-cropping rice experiments also indicated that the passivation effect of SMF materials on Cd-contaminated paddy fields was long-lasting and stable and that SMF is a more efficient and safe Cd passivation agent.

Application of a Perovskite NIR-LED with Highly Stable FAPbI3@SiO2 Core-Shell Nanocomposites in a SPR Sensing Platform.

In recent years, the demand for detection and diagnostic methods has consistently risen due to the aging of the population and the increase in the number of patients with chronic diseases. Label-free biomedical detection techniques have emerged as indispensable instruments for diagnosing a variety of diseases. The development of label-free and highly sensitive near-infrared (NIR) biomedical detection technology has attracted considerable attention. As a label-free, swift, and cost-effective analytical technique, it has demonstrated immense potential for a wide range of applications. We successfully assembled FAPbI3 near-infrared perovskite quantum dots (NIPQDs) into SiO2 shells using a rapid room-temperature atmospheric synthesis method, obtaining monodisperse FAPbI3@SiO2 nanocomposites (NCs) with a high photoluminescence quantum yield (PLQY) of 72%. Additionally, the incorporation of hydrophobic multi-branched trioctylphosphine oxide effectively passivated the surface defects of FAPbI3 NIPQDs and suppressed the hydrolysis rate of tetraethoxysilane, enabling the formation of a highly stable and high PLQY nanoscale-particle level within the FAPbI3@SiO2 core-shell structure. Notably, we successfully incorporated FAPbI3@SiO2 core-shell NCs onto InGaN blue chip as NIR excitation light sources for surface plasmon resonance sensing platforms, providing a novel platform for bioanalytical detection. With a detection sensitivity of 6302.5 nm/RIU, the system demonstrated high sensitivity, stability, and dependability. This achievement expands the biomedical research field's capacity for diagnosis, monitoring, and treatment.

Development of Conductive SiCx:H as a New Hydrogenation Technique for Tunnel Oxide Passivating Contacts.

Conductive hydrogenated silicon carbide (SiCx:H) is discovered as a promising hydrogenation material for tunnel oxide passivating contacts (TOPCon) solar cells. The proposed SiCx:H layer enables a good passivation quality and features a good electrical conductivity, which eliminates the need of etching back of SiNx:H and indium tin oxide (ITO)/Ag deposition for metallization and reduces the number of process steps. The SiCx:H is deposited by hot wire chemical vapor deposition (HWCVD) and the filament temperature (Tf) during deposition is systematically investigated. Via tuning the SiCx:H layer, implied open-circuit voltages (iVoc) up to 742 ± 0.5 mV and a contact resistivity (ρc) of 21.1 ± 5.4 mΩ·cm2 is achieved using SiCx:H on top of poly-Si(n)/SiOx/c-Si(n) stack at Tf of 2000 °C. Electrochemical capacitance-voltage (ECV) and secondary ion mass spectrometry (SIMS) measurements were conducted to investigate the passivation mechanism. Results show that the hydrogenation at the SiOx/c-Si(n) interface is responsible for the high passivation quality. To assess its validity, the TOPCon stack was incorporated as rear electron selective-contact in a proof-of-concept n-type solar cells featuring ITO/a-Si:H(p)/a-Si:H(i) as front hole selective-contact, which demonstrates a conversion efficiency up to 21.4%, a noticeable open-circuit voltage (Voc) of 724 mV and a fill factor (FF) of 80%.

[Hydrocalumite Passivation Effect and Mechanism on Heavy Metals in Different Cd-Contaminated Farmland Soils].

Hydrocalumite (Ca-Al-LDHs) is a new type of layered composite metal hydroxide that has a large specific surface area, high anion exchange performance, and high stability. This study focuses on the application of hydrocalumite to remediate different Cd-contaminated farmland soils. These were collected from the Lanping County in the Yunnan Province (highly polluted), Kunshan City in the Jiangsu Province (medium polluted), and Nanjing City in the Jiangsu Province (lowly polluted). Changes in the available Cd, Pb, Zn, and the morphological transformations of these heavy metals in the three soils were investigated through a passivation experiment; moreover, the immobilization mechanism of hydrocalumite was explored by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results showed that hydrocalumite could increase the soil pH and reduce the content of available Cd, Pb, and Zn:the maximum reduction in the available Cd reached 97.7%, 96.3%, and 91.8% in each of the three polluted soils, respectively. The easily exchangeable heavy metals were converted into carbonates, as well as into Fe-Mn oxide organic and residual forms following the addition of hydrocalumite:the passivation effect was more evident in the highly Cd-polluted soil than in the low and medium Cd-polluted soils. Since hydrocalumite possess several adsorption sites, the presence of carbonate impurities and reactive groups (e.g., hydroxyl and carboxyl groups) easily coordinated with Cd, Pb, and Zn can lead to a considerable reduction of heavy metal availability in the soils. Therefore, we conclude that hydrocalumite can be effectively applied to the remediation of farmland soils characterized by different Cd pollution levels.

Mechanism of PbI2 in Situ Passivated Perovskite Films for Enhancing the Performance of Perovskite Solar Cells.

Perovskite solar cells (PSCs) have gained tremendous research interest because of their tolerance of defects, low cost, and facile processing. In PSC devices, PbI2 has been utilized to passivate defects at perovskite film surfaces and GBs; however, a systematic mechanism of PbI2 in situ passivation for enhancing the solar cells efficiency has not been fully explored. Here, this work, we systematically studies the effect of the precise PbI2 ratio and the PbI2 in situ passivation mechanism based on trap density, carrier lifetime, Fermi level, and so forth. This study finds the appropriate ratio of I/Pb to be around 2.57:1 using energy-dispersive spectroscopy. After the moderate excess PbI2 in situ passivation, the trap density is reduced from 6.12 × 1016 to 3.38 × 1016 cm-3, and the carrier lifetime is extended from 168.35 to 368.77 ps by using fs-TA spectroscopy. This result indicates that the moderate excess PbI2 in situ passivation can reduce the trap density and suppress the nonradiative recombination. The efficiency of solar cell has shown a nearly 11.3% improvement of 19.55% for an I/Pb ratio of 2.57:1 compared with 2.69:1. It also demonstrates that the efficiency of PSCs can be enhanced effectively by PbI2 in situ passivation.