Navigation/traffic control satellite mission study. Volume 3 - System concepts

Satellite network for air traffic control, solar flare warning, and collision avoidanc

Efficiency Potential and Voltage Loss of Inorganic CsPbI2Br Perovskite Solar Cells

Inorganic perovskite solar cells show excellent thermal stability, but the reported power conversion efficiencies are still lower than for organic inorganic perovskites. This is mainly caused by lower open circuit voltages VOCs . Herein, the reasons for the low VOC in inorganic CsPbI2Br perovskite solar cells are investigated. Intensity dependent photoluminescence measurements for different layer stacks reveal that n i p and p i n CsPbI2Br solar cells exhibit a strong mismatch between quasi Fermi level splitting QFLS and VOC. Specifically, the CsPbI2Br p i n perovskite solar cell has a QFLS e amp; 8201; VOC mismatch of 179 amp; 8201;meV, compared with 11 amp; 8201;meV for a reference cell with an organic inorganic perovskite of similar bandgap. On the other hand, this study shows that the CsPbI2Br films with a bandgap of 1.9 amp; 8201;eV have a very low defect density, resulting in an efficiency potential of 20.3 with a MeO 2PACz hole transporting layer and 20.8 on compact TiO2. Using ultraviolet photoelectron spectroscopy measurements, energy level misalignment is identified as a possible reason for the QFLS e amp; 8201; VOC mismatch and strategies for overcoming this VOC limitation are discussed. This work highlights the need to control the interfacial energetics in inorganic perovskite solar cells, but also gives promise for high efficiencies once this issue is resolve

Perfluorinated Self Assembled Monolayers Enhance the Stability and Efficiency of Inverted Perovskite Solar Cells

Perovskite solar cells are among the most exciting photovoltaic systems as they combine low recombination losses, ease of fabrication, and high spectral tunability. The Achilles heel of this technology is the device stability due to the ionic nature of the perovskite crystal, rendering it highly hygroscopic, and the extensive diffusion of ions especially at increased temperatures. Herein, we demonstrate the application of a simple solution-processed perfluorinated self-assembled monolayer (p-SAM) that not only enhances the solar cell efficiency, but also improves the stability of the perovskite absorber and, in turn, the solar cell under increased temperature or humid conditions. The p-i-n-type perovskite devices employing these SAMs exhibited power conversion efficiencies surpassing 21%. Notably, the best performing devices are stable under standardized maximum power point operation at 85 °C in inert atmosphere (ISOS-L-2) for more than 250 h and exhibit superior humidity resilience, maintaining ∼95% device performance even if stored in humid air in ambient conditions over months (∼3000 h, ISOS-D-1). Our work, therefore, demonstrates a strategy towards efficient and stable perovskite solar cells with easily deposited functional interlayers

Root length and alveolar bone level of impacted canines and adjacent teeth after orthodontic traction: a long-term evaluation

Abstract Objective The aim of this retrospective study was to evaluate the long-term effects of orthodontic traction on root length and alveolar bone level in impacted canines and adjacent teeth. Material and Methods Sample consisted of 16 patients (nine males and seven females), mean initial age 11 years and 8 months presenting with unilaterally maxillary impacted canines, palatally displaced, treated with the same surgical and orthodontic approach. Teeth from the impacted-canine side were assigned as Group I (GI), and contralateral teeth as control, Group II (GII). The mean age of patients at the end of orthodontic treatment was 14 years and 2 months and the mean post-treatment time was 5 years and 11 months. Both contralateral erupted maxillary canines and adjacent teeth served as control. Root length and alveolar bone level (buccal and palatal) were evaluated on cone-beam computed tomography (CBCT) images. The comparison of root length and alveolar bone level changes between groups were assessed by applying paired t-test, at a significance level of 5% (p<0.05). Results There were no statistically significant differences in root length and buccal and palatal bone levels of canines and adjacent teeth among groups. Conclusions Impacted canine treatment by closed-eruption technique associated with canine crown perforation, has a minimal effect on root length and buccal and palatal alveolar bone level in both canine and adjacent teeth, demonstrating that this treatment protocol has a good long-term prognosis