A Holistic Study on the Effect of Annealing Temperature and Time on CH3NH3PbI3-Based Perovskite Solar Cell Characteristics

International audienceThe time and annealing temperature for the film crystallization in perovskite solar cells (PSCs) is critical and is at the stake of device optimization. It governs the crystallization process, the film’s morphorlogy and texture and the level of non-radiative defects, which in whole control the power conversion efficiency (PCE). However, deciphering each of these parameters in the device cell characteristics remains not totally clear. In this work, we led a holistic study considering temperature and time for the MAPbI 3 crystallization as a free parameter to study how the latter is impacting on the film’s characteristics and how the device figure of merit is affected. The results suggest that the crystallinity level of the grains plays an important role in the photo-current value whereas the morphology and PbI 2 impurities resulting from the onset of thermal decomposition of MAPbI 3 penalizes the cell photovoltage and the fill factor values. Based on this study, it is highlighted that flash high temperature annealing is beneficial to limit out-of-plane substrate grain boundaries, resulting in a device exhibiting 18.8% power conversion efficiency compared to 18.0% when more standard post-annealing procedure is employed

Real-Time TEM Imaging of Moisture-Induced Degradation of Triple Cation Mixed Halide Perovskite

International audienc

Understanding long-term stability of hybrid Perovskites

National audienc

Molecular‐Level Insight into Correlation between Surface Defects and Stability of Methylammonium Lead Halide Perovskite Under Controlled Humidity

International audienc

Colloidal Dispersions of Oxide Nanoparticles in Ionic Liquids: Elucidating the Key Parameters

This work presents a novel and comprehensive approach to predict and understand the stabilisation mechanisms of dispersions of nanoparticles in ionic liquids which is at present unpredictable. This opens up applications with new materials combining the properties of both nanoparticles and ionic liquids.</p

Molecular‐Level Insight into Correlation between Surface Defects and Stability of Methylammonium Lead Halide Perovskite Under Controlled Humidity

International audienc

Examining a Year-Long Chemical Degradation Process and Reaction Kinetics in Pristine and Defect-Passivated Lead Halide Perovskites

International audienceAs a promising solar energy harvesting technology, solution-processed metal halide perovskites (MHPs) are of great current interest in developing low-cost and efficient photovoltaic cells. Despite their excellent optoelectronic properties and the nascent advancements in compositional tailoring and interfacial engineering to develop high-performance MHPs, issues associated with the long-term environmental stability of these materials are yet to be addressed. Here we examine the moisture-induced cascade degradation reactions over a year for methylammonium lead iodide (MAPbI3)- and formamidinium-rich [Cs0.05(MA0.17FA0.83)0.95Pb(Br0.17I0.83)3] formulations at 40 and 85% relative humidity (RH) in the air. The transformative reactions at 85% RH lead to chemical degradation process in both MA-rich and FA-rich perovskites, yielding to the different organic and inorganic byproducts within a few hours, but the exposure to 40% RH retains the longevity of these materials up to several months. The defect passivation by the tetrapropylammonium cation (TPA+) imparts enhanced stability of MAPbI3 particles, irrespective of the exposure conditions to water vapor. By resolving thin-film morphology at sub-nanometer to nanometer resolution using solid-state (ss)NMR spectroscopy and X-ray diffraction techniques, kinetics of degradation reactions and structural insights into the inorganic/organic interfaces and degradation products are obtained and compared. Our findings provide mechanistic details into the cascade degradation reactions in pristine and defect-passivated MHPs, enabling guidance for novel passivating and interfacial engineering strategies to further improve the robustness of the MHPs with respect to environmental stressors

Lentiviral Mediating Genetic Engineered Mesenchymal Stem Cells for Releasing IL-27 as a Gene Therapy Approach for Autoimmune Diseases

Objective: Autoimmune diseases precede a complex dysregulation of the immune system. T helper17 (Th17) and interleukin (IL)-17 have central roles in initiation of inflammation and subsequent autoimmune diseases. IL-27 significantly controls autoimmune diseases by Th17 and IL-17 suppression. In the present study we have created genetic engineered mesenchymal stem cells (MSCs) that mediate with lentiviral vectors to release IL-27 as an adequate vehicle for ex vivo gene therapy in the reduction of inflammation and autoimmune diseases. Materials and Methods: In this experimental study, we isolated adipose-derived MSCs (AD-MSCs) from lipoaspirate and subsequently characterized them by differentiation. Two subunits of IL-27 (p28 and EBI3) were cloned in a pCDH-513B-1 lentiviral vector. Expressions of p28 and EBI3 (Epstein-Barr virus induced gene 3) were determined by real time polymerase chain reaction (PCR). MSCs were transduced by a pCDH-CMV-p28-IRESEBI3- EF-copGFP-Pur lentiviral vector and the bioassay of IL-27 was evaluated by IL-10 expression. Results: Cell differentiation confirmed true isolation of MSCs from lipoaspirate. Restriction enzyme digestion and sequencing verified successful cloning of both p28 and EBI3 in the pCDH-513B-1 lentiviral vector. Real time PCR showed high expressions level of IL-27 and IL-10 as well as accurate activity of IL-27. Conclusion: The results showed transduction of functional IL-27 to AD-MSCs by means of a lentiviral vector. The lentiviral vector did not impact MSC characteristics

Defect Passivation via the Incorporation of Tetrapropylammonium Cation Leading to Stability Enhancement in Lead Halide Perovskite

International audienceImproving the performances of photovoltaic (PV) devices by suppressing non-radiative energy losses through the passivation of surface defects and enhancing perovskite solar cells stability to the level of standard PV materials represents one critical challenge in the field of perovskite solar cells. We report the beneficial features of introducing a tetrapropylammonium quaternary ammonium (TPA +) cation that combines two key functionalities, namely surface passivation of CH3NH3PbI3 nanocrystals through strong ionic/electrostatic interaction with the surface and bulk passivation via formation of type I heterostructure which acts as a barrier for recombination and reduces water ingress. As a result, non-encapsulated perovskite films with only 2 mol % of TPA + reached power conversion efficiencies over 17% under spectral irradiance corresponding to air mass (A.M.) 1.5G conditions. Furthermore, these films retain more than 85% of the initial 2 performance for over 1500 hours under ambient conditions, including a relative humidity of ~55±5%. The stability of these films is also significantly enhanced at 60 °C thermal stress or under 85% humidity storage. Perovskite thin films before and after the TPA + incorporation are characterized by X-ray diffraction, solid-state NMR spectroscopy, optical absorption spectroscopy and SEM imaging

Deltamethrin-impregnated bed nets and curtains in an anthroponotic cutaneous leishmaniasis control program in northeastern Iran

<b>Background: </b> Anthroponotic cutaneous leishmaniasis (ACL) has long been a significant public health prob-lem in northeastern Iran. The objective of this study was to determine the efficacy of deltamethrin-impregnated vs. nonimpregnated bed nets (NIBs) and curtains (NICs) in ACL control. <b> Patients: </b> Deltamethrin-impregnated bed nets (IBs) and curtains (ICs) with 25 mg ai/m²were distributed among 160 households in one district and NIBs and NICs were distributed among the same number of households in another district. A third district with a similar numbers of households served as a control. Health education mes-sages were disseminated to ensure the population&#x2032;s complicance with the proper use of bed nets and curtains. Sticky paper traps were used to assess the effect of insecticide-impregnated bed nets and curtains on the density of Phlebotomus sergenti. Deltamethrin susceptibility and also bioassay tests were carried out on the species by WHO standard method. Case findings were done by house-to-house visits once a season and all the inhabitants of the selected households in each district were examined. <b> Results: </b> IBs and ICs provided good protection against sandfly bites and reduced the transmission of ACL in the intervention district, while NIBs and NICs provided no protection. There was no significant difference in monthly density of P. sergenti indoors and outdoors among the districts (P>0.05). This species was susceptible to delta-methrin in the field population in the area. Bioassays confirmed that the nets treated with deltamethrin remained effective for more than 3 months. <b>Conclusion: </b> Personal protection is an effective and sustainable means of preventing and controlling ACL and can reduce dependence on insecticides. We encourage the use of IBs and ICs to control ACL in other high-risk areas of Iran and Afghanistan during the active season of sandflies