Direct Observation of Sub-picosecond Hole Injection from Lead Halide Perovskite by Differential Transient Transmission Spectroscopy

Efficient charge separation at the interfaces between the perovskite and with the carrier transport layers is crucial for perovskite solar cells to achieve high power conversion efficiency. We systematically investigate the hole injection dynamics from MAPbI$_3$ perovskite to three typical hole transport materials (HTMs) PEDOT:PSS, PTAA and NiO$_x$ by means of pump-probe transmission measurements. We photoexcite only near the MAPbI$_3$/HTM interface or near the back surface, and measure the differential transient transmission between the two excitation configurations to extract the carrier dynamics directly related to the hole injection. The differential transmission signals directly monitor the hole injections to PTAA and PEDOT:PSS being complete within 1 and 2 ps, respectively, and that to NiO$_x$ exhibiting an additional slow process of 40 ps time scale. The obtained injection dynamics are discussed in comparison with the device performance of the solar cells containing the same MAPbI$_3$/HTM interfaces.Comment: 5 pages, 5 figure

Development of a New Class of Thiocyanate-Free Cyclometalated Ruthenium(II) Complex for Sensitizing Nanocrystalline TiO 2

We designed and developed a new class of thiocyanate-free cyclometalated ruthenium sensitizers for sensitizing nanocrystalline TiO2 solar cells. This complex shows appreciably broad absorption range. Anchoring to nanocrystalline TiO2 films for light to electrical energy conversion in regenerative photoelectrochemical cells achieves efficient sensitization to TiO2 electrode. With this new sensitizer, there were a power conversion efficiency of 4.76%, a short-circuit photocurrent density of 11.21 mA/cm2, an open-circuit voltage of 0.62 V, and a fill factor of 0.68 obtained under standard AM 1.5 sunlight

Immune Functions of Former Poison Gas Workers I. Mitogenic response of lymphocytes and serum factors

The relation of depressed immune function to carcinogenesis has been estimated in the living body. The authors have measured the immunological parameters in former poison gas workers, a group having a high risk of carcinogenesis, for comparison with age matched normal controls and the following results were obtained. 1) With regard to serum factors, no significant difference could be demonstrated between normal controls and poison gas workers in such immunoglobulins as IgG, IgA, and IgM, in acute phase reactants such as α1-AT, α1-AG, α2-HS and C3 and in such tumor markers as CEA, ferritin, and β2-microglobulin. Furthermore, no difference could be observed in the positive rate of immune complex and in complement activity. 2) No difference could be observed between the two groups with regard to tuberculin skin reaction and number of lymphocytes, but the longer the duration of work at the poison gas factory, the more significant was the increase in those who showed negative tuberculin skin reaction. 3) In comparison with normal controls, mitogenic response to PHA showed a significant decrease in poison gas workers, but no significant difference could be seen in mitogenic response to Con A and PPD and in mixed lymphocyte reaction. 4) No significant difference could be demonstrated between the two groups in the inhibitory effects of serum on mitogenic response to PHA and Con A and on mixed lymphocyte reaction

Supercritical fluid processing of mesoporous crystalline TiO2 thin films for highly efficient dye-sensitized solar cells

In this study, a high light-to-electricity conversion efficiency of 5.14% was achieved by applying a TiO2 thin film with a thickness of 1.87 µm as an electrode material under an AM 1.5 solar light (100 mW cm−2). This high efficiency can be attributed to post-treatment by the supercritical fluid process and the addition of nanoparticles to the thin film. Supercritical fluid treatment is shown to significantly enhance the thermal stability of these thin films. Thus, the high porosity of the treated films was maintained even upon calcination at a high temperature. Additionally, the addition of crystalline light scattering nanoparticles in the thin film not only increases the crystallinity of the thin films but also ensures capture of the incident light and increases the efficiency of light harvesting. The thin film with well-preserved mesopores among the nanoparticles can capture the incident light efficiently and further increase efficiency of light harvesting, which leads to the remarkably high light-to-electricity conversion efficiency

Destruxin E Decreases Beta-Amyloid Generation by Reducing Colocalization of Beta-Amyloid-Cleaving Enzyme 1 and Beta-Amyloid Protein Precursor

Alzheimer-disease-associated beta-amyloid (A beta) is produced by sequential endoproteolysis of beta-amyloid protein precursor (beta APP): the extracellular portion is shed by cleavage in the juxtamembrane region by beta-amyloid-cleaving enzyme (BACE)/beta-secretase, after which it is cleaved by presenilin (PS)/gamma-secretase near the middle of the transmembrane domain. Thus, inhibition of either of the secretases reduces A beta generation and is a fundamental strategy for the development of drugs to prevent Alzheimer disease. However, it is not clear how small compounds reduce A beta production without inhibition of the secretases. Such compounds are expected to avoid some of the side effects of secretase inhibitors. Here, we report that destruxin E (Dx-E), a natural cyclic hexadepsipeptide, reduces A beta generation without affecting BACE or PS/gamma-secretase activity. In agreement with this, Dx-E did not inhibit Notch signaling. We found that Dx-E decreases colocalization of BACE1 and beta APP, which reduces beta-cleavage of beta APP. Therefore, the data demonstrate that Dx-E represents a novel A beta-reducing process which could have fewer side effects than secretase inhibitors. Copyright (C) 2009 S. Karger AG, Base

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

Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks

无线传感器网络，作为全球未来十大技术之一，集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术，可实时感知、采集、处理、传输网络分布区域内的各种信息数据，在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议，并针对大规模的无线传感器网络设计了一种树状路由协议，它根据节点地址信息来形成路由，从而简化了复杂繁冗的路由表查找和维护，节省了不必要的开销，提高了路由效率，实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR（AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位：工学硕士院系专业：信息科学与技术学院通信工程系_通信与信息系统学号：2332007115216

Computational Verification of So-Called Perovskite Solar Cells as PbI_6^<4−> -Aligned Solar Cells

Effective sensitizing components in so-called perovskite solar cells (PSC) are lead hexaiodide (PbI_6^) salts of PbI_6^ (MeNH_3^+)n (n = 2∼4). Density-functional-theory-based molecular modeling (DFT/MM) of X-ray crystalline structure of PbI_6^/MeNH_3^+ salt (FOLLIB) verifies that the packing unit of FOLLIB has UV/Vis absorption spectrum at λmax = 424 nm, giving pale yellow color as complementary color. DFT/MM of the horizontal component in the FOLLIB gives narrow energy gap of 0.3 eV, verifying remarkable semiconducting property through tight alignments of PbI_6^ components coupled with MeNH_3^+. DFT/MM of the central PbI_6^/MeNH_3^+ components verifies that the central component has UV/Vis absorption spectra with respective λmax = 570 nm, λmax = 762 nm and λmax = 945 nm, and plays an essential role as panchromatic sensitizers. In addition, their equilibrium geometric structures show slightly hypsochromic UV/Vis absorption spectra at respective λmax = 486 nm, λmax = 560 nm, and λmax = 563 nm as results of migration of MeNH_3^+ close to PbI_6^. DFT/MM also verifies that PbI_6^ components align tightly to nanocrystalline TiO_2 (nc-TiO_2) and to spiro-OMeTAD in PSC through electron density induced by van der Waals interaction. Electron density-based alignments of PbI_6^ components well explain unidirectional and leakage-free electron diffusion leading to high open-circuit voltage in PbI_6^-aligned solar cells. At the same time, the semiconducting and panchromatic sensitizing layer of PbI_6^/MeNH_3^+ components contribute to excellent short-circuit photocurrent of PbI_6^-aligned solar cells