The impact of CBz-PAI interlayer in various HTL-based flexible perovskite solar cells: A drift-diffusion numerical study.

In perovskite solar cells (PSCs), the charge carrier recombination obstacles mainly occur at the ETL/perovskite and HTL/perovskite interfaces, which play a decisive role in the solar cell performance. Therefore, this study aims to enhance the flexible PSC (FPSC) efficiency by adding the newly designed CBz-PAI-interlayer (simply CBz-PAI-IL) at the perovskite/HTL interface. In addition, substantial work has been carried out on five different HTLs (Se/Te-Cu2O, CuGaO2, V2O5, and CuSCN, including conventional Spiro-OMeTAD as a reference HTL with and without CBz-PAI-IL), using drift-diffusion simulation to find suitable FPSC design to attain the maximum PCE. Interestingly, PET/ITO/AZO/ZnO NWs/FACsPbBrI3/CBz-PAI/Se/Te-Cu2O/Au device architecture demonstrates the highest achievable power conversion efficiency (PCE) of 27.9 %. The findings of this study confirmed that the reference device (without IL) displays a large valence band edge (VBE)/highest occupied molecular orbital (HOMO) energy level misalignment compared to the modified interface device (with CBz-PAI-IL that reduces VBE/HOMO level mismatch) that eases the hole transport, simultaneously, it reduces the charge carrier recombinations at the interface, resulting in diminished Voc losses in the device. Furthermore, the influence of perovskite absorber thickness and defect density, parasitic resistances, and working temperature are systematically examined to govern the superior FPSC efficiency and concurrently understand the device physics.

Control of ZnO nanowires growth in flexible perovskite solar cells: A mini-review.

Due to their excellent properties, Zinc oxide nanowires (ZnO NW) have been attractive and considered as a promising electron-transporting layer (ETL) in flexible Perovskite Solar Cells (FPSCs). Since the first report on ZnO NWs-based FPSCs giving 2.6 % power conversion efficiency (in 2013), great improvements have been made, allowing to reach up to∼15 % nowadays. However, some issues still need to be addressed, especially on flexible substrates, to achieve uniform and well-aligned ZnO NWs via low-cost chemical solution techniques. Several parameters, such as the growing method (time, temperature, precursors concentration), addition of seed layer (thickness, roughness, annealing temperature) and substrate (rigid or flexible), play a crucial role in ZnO NWs properties (i.e., length, diameter, density and aspect ratio). In this review, these parameters allowing to control the properties of ZnO NWs, like the growth techniques, utilization of seed layers and the growing method (time or precursors concentration) have been summarized. Then, a particular focus on the ZnO NW's role in FPSCs as well as the use of these results on the development of ZnO NWs-based FPSCs have been highlighted.

Enhancing perovskite solar cell performance through PbI2 in situ passivation using a one-step process: experimental insights and simulations.

The in situ passivation of a methylammonium lead triiodide (MAPbI3) phase spin-coated via a one-step process was experimentally investigated to elucidate their fundamental properties. Structural analysis revealed that MAPbI3 adopts a tetragonal crystal structure with a small excess of PbI2 (0.03 M) segregating at grain boundaries. Optical characterization indicated a band gap of 1.53 eV, highlighting the material's potential as an effective visible light absorber. To facilitate the fabrication of efficient perovskite solar cells (PSCs), we employed a primary n-i-p planar structure (ITO/SnO2/MAPbI3/spiro-OMeTAD/Au) in drift-diffusion SCAPS-1D simulations using experimental data from MAPbI3 layers containing excess PbI2. The simulations predicted a high power conversion efficiency (PCE) of approximately 24%. We further analyzed the impact of series resistance, shunt resistance, MAPbI3 thickness, defect density, as well as radiative and Auger recombination on photovoltaic performance, aiming to identify optimal parameters for enhanced device efficiency. Additionally, the use of ohmic contacts with AZO and IZO as the front and rear contacts, respectively, in the optimized device structure (AZO/SnO2/MAPbI3/spiro-OMeTAD/IZO) resulted in a PCE of 26.03%. These findings provide valuable insights for future research aimed at achieving high-efficiency bifacial MAPbI3 perovskite solar cells.

Lead-free, formamidinium germanium-antimony halide (FA4GeSbCl12) double perovskite solar cells: the effects of band offsets.

Double halide perovskites have received massive attention due to their low toxicity, tunable bandgap, structural flexibility, and stability as compared to conventional 3D lead halide perovskites. Particularly, newly discovered formamidinium germanium-antimony halide (FA4GeSbCl12) double perovskites offer an excellent bandgap (∼1.3 eV) for solar cell (SC) applications. Therefore, in this study, for the first time, we have simulated FTO/TiO2/FA4GeSbCl12/Cu2O/Au planar SCs using SCAPS-1D, showing a maximum power conversion efficiency of 22.5% with Jsc = 34.52 mA cm-2, Voc = 0.76 V, and FF = 85.1%. The results show that the variation in valence and conduction band offsets (-0.4 to +0.2 eV and -0.4 to +0.57 eV) at the ETL/absorber and absorber/HTL interfaces dominate the SC performance. Also, different absorber defect densities (1 × 1014-1 × 1020 cm-3) and thicknesses (200-3000 nm) effectively influence the PCE. Moreover, simulated impedance spectroscopy (IS) data (through SCAPS-1D) were fitted using equivalent electrical circuits to extract relevant parameters, including Rs, RHF, and RLF, allowing us to better discuss the physics of the device. The fitted IS results strongly revealed that enhanced SC performance is associated with higher recombination resistance and a larger recombination lifetime. Likewise, a slight variation in the Rs (0 to 2.5 Ω cm2) highly impacts the PCE (22.5% to 19.7%). Furthermore, a tandem cell is designed by combining the top cell of ethylenediammonium-FASnI3 perovskite with the FA4GeSbCl12 bottom cell using a filtered spectrum strategy, which opens the door for multi-junction SC applications. These findings firmly reveal that the appropriate energy level alignment at interfaces with suitable material properties is the key to boosting SC performance.

Low-Temperature Hydrothermal Growth of ZnO Nanowires on AZO Substrates for FACsPb(IBr)3 Perovskite Solar Cells.

Electron and hole transport layers (ETL and HTL) play an essential role in shaping the photovoltaic performance of perovskite solar cells. While compact metal oxide ETL have been largely explored in planar n-i-p device architectures, aligned nanowires or nanorods remain highly relevant for efficient charge extraction and directional transport. In this study, we have systematically grown ZnO nanowires (ZnO NWs) over aluminum-doped zinc oxide (AZO) substrates using a low-temperature method, hydrothermal growth (HTG). The main growth parameters were varied, such as hydrothermal precursors concentrations (zinc nitrate hexahydrate, hexamethylenetetramine, polyethylenimine) and growing time, in order to finely control NW properties (length, diameter, density, and void fraction). The results show that ZnO NWs grown on AZO substrates offer highly dense, well-aligned nanowires of high crystallinity compared to conventional substrates such as FTO, while demonstrating efficient FACsPb(IBr)3 perovskite device performance, without the requirement of conventional compact hole blocking layers. The device performances are discussed based on NW properties, including void fraction and aspect ratio (NW length over diameter). Finally, AZO/ZnO NW-based devices were fabricated with a recent HTL material based on a carbazole moiety (Cz-Pyr) and compared to the spiro-OMeTAD reference. Our study shows that the Cz-Pyr-based device provides similar performance to that of spiro-OMeTAD while demonstrating a promising stability in ambient conditions and under continuous illumination, as revealed by a preliminary aging test.

The Provision of Dental Care to COVID-19 Survivors: A Concise Review.

AIMS: It has been reported that there are a certain percentage of COVID-19 patients who recover but suffer from devastating permanent organ damage or failure. Others suffer from long Covid syndrome, with prolonged symptoms that persist more than 12 weeks. However, there is scarcity of literature regarding the provision of dental treatment for these two groups of patients. This manuscript reviews the impact of multi-system involvement on the provision of dental care to these patients. MATERIALS AND METHODS: A search of literature was done in PubMed-Medline and Scopus databases to review the available literature on COVID-19 impacts on pulmonary, cardiovascular, haematologic, renal, gastrointestinal, endocrine, and neurologic systems and respective management in dental clinical settings. RESULTS: The literature search from PubMed-Medline and Scopus databases resulted in 74 salient articles that contributed to the concise review on COVID-19 effects on pulmonary, cardiovascular, haematologic, renal, gastrointestinal, endocrine, and neurologic systems and/or its respective dental management recommendations. CONCLUSIONS: This concise review covers the management of post COVID-19 patients with pulmonary, cardiovascular, haematologic, renal, gastrointestinal, endocrine, or neurologic system complications.