With regard to perovskite solar cells (PSCs), a zinc oxide (ZnO) planar architecture has significant advantages from the upscaling perspective in terms of cost effectiveness and low-temperature processing compared to architectures with a mesoporous titanium dioxide (TiO 2 ) layer. Nevertheless, the perovskite (PVK) materials are unstable on a ZnO electron transport layer (ETL) during the annealing process. Herein, we discovered that the PVK material on top of the ETL changes to lead iodide (PbI 2 ) because of the presence of oxygen agents on the surface of ZnO. To tackle this issue, a hybrid photoelectrode of ZnO/graphene quantum dots (GQDs) is prepared and used as an ETL. As a result, green synthesized GQDs not only passivate the oxygen agents on the surface of the ZnO but also extract electrons rapidly from the PVK film to decrease the recombination of electron−hole pairs. Herein, findings reveal that PSC on ZnO:GQD ETL shows a power conversion efficiency (PCE) of up to 17% on fluorine tin oxide (FTO) under AM1.5G illumination. Consequently, the introduction of multifunctional GQD as an additive in ZnO ETL in PSCs displays a new and efficient tool in terms of environmental impact and economic feasibility for PSC commercialization.
Hole transport material-free perovskite solar cells (HF-PSCs) offer low-cost photovoltaic devices. For development and commercialization, they are more attractive than the expensive HTLcontained perovskite solar cells. Herein, we focused on enhancing the stability and efficiency of HF-PSCs with the malonic acid (MA) addition to the methylammonium lead iodide. The introduced additive increases the perovskite crystallinity and assembles a perovskite layer with larger grains along with fewer surface defects. In addition, the MA-modified HF-PSCs show suppressed charge recombination within devices, and a lower charge trap density has been obtained for them. A considerable power conversion efficiency of 14.14% is achieved for MA-modified HF-PSCs, higher than the performance of 11.88% for the untreated HF-PSCs. Finally, MA-based HF-PSCs show higher shelf stability than the control HF-PSCs. It is because the MA-modified perovskite layer with passivated grain boundaries is better at repelling water.
Due to their outstanding performance and ease of processing in low temperature solutions, organometal hybrid perovskite solar cells (HPSCs) have recently become a hot topic. Current solution processes extensively use...
Polymethyl methacrylate (PMMA) mechanical strength still has a couple of disadvantages form long term denture. This work aims to evaluate the influence of Zirconium nanoparticle (ZrO2) with various concentrations (0.15, 0.35, 0.6, 0.9) on tensile, compression, fatigue strength, and hardness test. The rise of the ZrO2 nanoparticles ratio yielded to a proportional increase in the material composite strength of tensile. In addition, the compression test showed that the ZrO2 ratio rise increased the compressive strength of the compound material. As for the hardness test, it has been noted that the article has a high hardness ratio and is almost perfect. Moreover, the rate of fatigue test, which is a measure of the susceptibility of corrosion-resistant material, yielded good result in which the content has shown the ability to resist erosion for a long time. All over, the results mentioned above showed reliable capacity for denture base material with improved strength, fatigue, hardness and compression with the of addition ZrO2 nanoparticles to PMMA.
Elements of high purity (99.999) ,were used to prepare the alloy , Bi ,Sn,Zn and Cu .Two types alloy Bi – Sn – Zn and Bi – Sn – Cu were prepared by mechanical alloying technique (MA) .Annealing at 100 °Cfor 8 hours was applied for the resulting alloys . X-ray diffraction and differential scanning colorimetriy were tested for the two types of alloy before and after annealing. The best results was noticed in the ternary alloythat prepared at 4 hours milling time ,and annelid at 100 °C, for 8 hours ,under static air.
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