Influence of the Porosity of the TiO 2

The structure of mesoporous TiO2 (mp-TiO2) films is crucial to the performance of mesoporous perovskite solar cells (PSCs). In this study, we fabricated highly porous mp-TiO2 films by doping polystyrene (PS) spheres in TiO2 paste. The composition of the perovskite films was effectively improved by modifying the mass fraction of the PS spheres in the TiO2 paste. Due to the high porosity of the mp-TiO2 film, PbI2 and CH3NH3I could sufficiently infiltrate into the network of the mp-TiO2 film, which ensured a more complete transformation to CH3NH3PbI3. The surface morphology of the mp-TiO2 film and the photoelectric performance of the perovskite solar cells were investigated. The results showed that an increase in the porosity of the mp-TiO2 film resulted in an improvement in the performance of the PSCs. The best device with the optimized mass fraction of 1.0 wt% PS in TiO2 paste exhibited an efficiency of 12.69%, which is 25% higher than the efficiency of the PSCs without PS spheres

Online Modelling and Calculation for Operating Temperature of Silicon-Based PV Modules Based on BP-ANN

The operating temperature of silicon-based solar modules has a significant effect on the electrical performance and power generation efficiency of photovoltaic (PV) modules. It is an important parameter for PV system modeling, performance evaluation, and maximum power point tracking. The analysis shows that the results of physics-based methods always change with seasons and weather conditions. It is difficult to measure all the needed variables to build the physics-based model for the calculation of operating temperature. Due to the above problem, the paper proposes an online method to calculate operating temperature, which adopts the back propagation artificial neural network (BP-ANN) algorithm. The comparative analysis is carried out using data from the empirical test platform, and the results show that both the BP-ANN and the support vector machine (SVM) method can reach good accuracy when the dataset length was over six months. The SVM method is not suitable for the temperature modeling because its computing time is too long. To improve the performance, wind speed should be taken as one of the models’ input if possible. The proposed method is effective to calculate the operating temperature of silicon-based solar modules online, which is a low-cost soft-sensing solution

Ultrafast Electron Injection from Photoexcited Perovskite CsPbI3 QDs into TiO2 Nanoparticles with Injection Efficiency near 99%

Photoexcited electron injection dynamics from CsPbI3 quantum dots (QDs) to wide gap metal oxides are studied by transient absorption spectroscopy. Experimental results show under a low excitation intensity that ∼99% of the photoexcited electrons in CsPbI3 QDs can be injected into TiO2 with a size-dependent rate ranging from 1.30 × 1010 to 2.10 × 1010 s–1, which is also ∼2.5 times faster than that in the case of ZnO. A demonstration QD-sensitized solar cell based on a CsPbI3/TiO2 electrode is fabricated that delivers a power conversion efficiency of 5%

Highly Luminescent Phase-Stable CsPbI3 Perovskite Quantum Dots Achieving Near 100% Absolute Photoluminescence Quantum Yield

Perovskite quantum dots (QDs) as a new type of colloidal nanocrystals have gained significant attention for both fundamental research and commercial applications owing to their appealing optoelectronic properties and excellent chemical processability. For their wide range of potential applications, synthesizing colloidal QDs with high crystal quality is of crucial importance. However, like most common QD systems such as CdSe and PbS, those reported perovskite QDs still suffer from a certain density of trapping defects, giving rise to detrimental nonradiative recombination centers and thus quenching luminescence. In this paper, we show that a high room-temperature photoluminescence quantum yield of up to 100% can be obtained in CsPbI3 perovskite QDs, signifying the achievement of almost complete elimination of the trapping defects. This is realized with our improved synthetic protocol that involves introducing organolead compound trioctylphosphine–PbI2 (TOP–PbI2) as the reactive precursor, which also leads to a significantly improved stability for the resulting CsPbI3 QD solutions. Ultrafast kinetic analysis with time-resolved transient absorption spectroscopy evidence the negligible electron or hole-trapping pathways in our QDs, which explains such a high quantum efficiency. We expect the successful synthesis of the “ideal” perovskite QDs will exert profound influence on their applications to both QD-based light-harvesting and -emitting devices

Colloidal Synthesis of Air-Stable Alloyed CsSn1–xPbxI3 Perovskite Nanocrystals for Use in Solar Cells

Organic–inorganic hybrid perovskite solar cells have demonstrated unprecedented high power conversion efficiencies in the past few years. Now, the universal instability of the perovskites has become the main barrier for this kind of solar cells to realize commercialization. This situation can be even worse for those tin-based perovskites, especially for CsSnI3, because upon exposure to ambient atmosphere the desired black orthorhombic phase CsSnI3 would promptly lose single crystallinity and degrade to the inactive yellow phase, followed by irreversible oxidation into metallic Cs2SnI6. By alloying CsSnI3 with CsPbI3, we herein report the synthesis of alloyed perovskite quantum dot (QD), CsSn1–xPbxI3, which not only can be phase-stable for months in purified colloidal solution but also remains intact even directly exposed to ambient air, far superior to both of its parent CsSnI3 and CsPbI3 QDs. Ultrafast transient absorption spectroscopy studies reveal that the photoexcited electrons in the alloyed QDs can be injected into TiO2 nanocrystals at a fast rate of 1.12 × 1011 s–1, which enables a high photocurrent generation in solar cells

The Main Progress of Perovskite Solar Cells in 2020–2021

Perovskite solar cells (PSCs) emerging as a promising photovoltaic technology with high efficiency and low manufacturing cost have attracted the attention from all over the world. Both the efficiency and stability of PSCs have increased steadily in recent years, and the research on reducing lead leakage and developing eco-friendly lead-free perovskites pushes forward the commercialization of PSCs step by step. This review summarizes the main progress of PSCs in 2020 and 2021 from the aspects of efficiency, stability, perovskite-based tandem devices, and lead-free PSCs. Moreover, a brief discussion on the development of PSC modules and its challenges toward practical application is provided

BMP-6 promotes E-cadherin expression through repressing δEF1 in breast cancer cells

<p>Abstract</p> <p>Background</p> <p>Bone morphogenetic protein-6 (BMP-6) is critically involved in many developmental processes. Recent studies indicate that BMP-6 is closely related to tumor differentiation and metastasis.</p> <p>Methods</p> <p>Quantitative RT-PCR was used to determine the expression of BMP-6, E-cadherin, and δEF1 at the mRNA level in MCF-7 and MDA-MB-231 breast cancer cells, as well as in 16 breast cancer specimens. Immunoblot analysis was used to measure the expression of δEF1 at the protein level in δEF1-overexpressing and δEF1-interfered MDA-MB-231 cells. Luciferase assay was used to determine the rhBMP-6 or δEF1 driven transcriptional activity of the E-cadherin promoter in MDA-MB-231 cells. Quantitative CHIP assay was used to detect the direct association of δEF1 with the E-cadherin proximal promoter in MDA-MB-231 cells.</p> <p>Results</p> <p>MCF-7 breast cancer cells, an ER⁺cell line that expressed high levels of BMP-6 and E-cadherin exhibited very low levels of δEF1 transcript. In contrast, MDA-MB-231 cells, an ER^-cell line had significantly reduced BMP-6 and E-cadherin mRNA levels, suggesting an inverse correlation between BMP-6/E-cadherin and δEF1. To determine if the same relationship exists in human tumors, we examined tissue samples of breast cancer from human subjects. In 16 breast cancer specimens, the inverse correlation between BMP-6/E-cadherin and δEF1 was observed in both ER⁺cases (4 of 8 cases) and ER^-cases (7 of 8 cases). Further, we found that BMP-6 inhibited δEF1 transcription, resulting in an up-regulation of E-cadherin mRNA expression. This is consistent with our analysis of the E-cadherin promoter demonstrating that BMP-6 was a potent transcriptional activator. Interestingly, ectopic expression of δEF1 was able to block BMP-6-induced transactivation of E-cadherin, whereas RNA interference-mediated down-regulation of endogenous δEF1 in breast cancer cells abolished E-cadherin transactivation by BMP-6. In addition to down-regulating the expression of δEF1, BMP-6 also physically dislodged δEF1 from E-cadherin promoter to allow the activation of E-cadherin transcription.</p> <p>Conclusion</p> <p>We conclude that repression of δEF1 plays a key role in mediating BMP-6-induced transcriptional activation of E-cadherin in breast cancer cells. Consistent with the fact that higher level of δEF1 expression is associated with more invasive phenotype of breast cancer cells, our collective data suggests that δEF1 is likely the switch through which BMP-6 restores E-cadherin-mediated cell-to-cell adhesion and prevents breast cancer metastasis.</p

Dye-sensitized Solar Cells

Для функционирования всего во Вселенной необходим особый „материал“ - энергия. Земля не является исключением. На земле существует много видов источников энергии. Но откуда берется энергия Земли? Ответ заключается в том, что все растет под солнцем. Развитие возобновляемых источников энергии имеет стратегическое значение для достижения устойчивого энергоснабжения. Имитация естественного фотосинтеза является конечной целью эффективного преобразования солнечной энергии. Фотоэлектрические технологии широко используются в промышленности и в будущем станут одним из основных источников энергии. Разрабатывая новые материалы и структуры, эффективность фотоэлектрического преобразования солнечных элементов будет повышаться день ото дня и солнечные элементы будут привлекать все больше и больше внимания. В этой книге представлены принципы преобразования солнечной энергии в фотоэлектрическую и описываются связанные с этим физические и химические процессы. Также обсуждаются механизмы, влияющие на работу солнечных элементов.Используемые программы Adobe AcrobatThe operation of everything in the universe needs a special „material“-energy. The earth is no exception. There are many kinds of energy sources on earth. But where does the earth‘s energy come from? The answer is that everything grows under the sun. Developing renewable energy is of strategic importance to achieve sustainable energy supply. Simulating natural photosynthesis is the ultimate goal of effi cient solar energy conversion. Photovoltaic technology has been widely used in industry and will be one of the major energy sources in the future. Developing new materials and structures, the photoelectric conversion effi ciency of solar cells will be improved day by day, and solar cells will attract more and more attention. This book presents principles of solar photovoltaic conversion, and introduces the physical and chemical processes involved. Mechanisms which affect solar cell performance are also discussed.Presents a comphensive overview for Dye-sensitized Solar CellIntroduces theoretical and technica