Perovskite heterojunction based on CH3NH3PbBr3 single crystal for high-sensitive self-powered photodetector

Perovskite single crystals exhibit extraordinary optoelectronic performances due to their advantages such as low trap-state densities, long carrier diffusion, and large absorption coefficient, and thus, photodetectors based on perovskite single crystals have attracted much research interest. Unlike the reported one-component single-crystal perovskite photodetectors, here, we have developed a facile two-step approach to fabricate a core-shell heterojunction based on the CH3NH3PbBr3 single crystal. A photodetector made of the as-prepared perovskite heterojunction renders the feature of self-power attributed to a built-in electric field in the junction and exhibits a wavelength-dependent responsivity with a peak responsivity up to 11.5 mA W−1 under 450 nm irradiation at zero bias, which is one order of magnitude higher than the CH3NH3PbBr3 single crystal and shows a maximum external quantum efficiency of 3.17%, also higher than the reported 0.2% of the CH3NH3PbBr3 single crystal. Our work may lead to more efficient self-powered heterojunction systems based on perovskite single crystals.Publisher PDFPeer reviewe

ANALYSIS OF FACTORS CAUSING WATER DAMAGE TO LOESS DOUBLE-ARCHED TUNNEL BASED ON TFN-AHP

In order to analysis the factors causing water damage to loess double-arched tunnel, this paper conducts field investigation on water damage to tunnels on Lishi-Jundu Expressway in Shanxi, China, confirms its development characteristics, builds an index system (covering 36 evaluation indexes for construction condition, design stage, construction stage, and operation stage) for the factors causing water damage to loess double-arched tunnel, applies TFN-AHP (triangular fuzzy number-analytic hierarchy process) in calculating the weight of indexes at different levels, and obtains the final sequence of weight of the factors causing water seepage to loess double-arched tunnel. It is found out that water damage to loess double-arched tunnel always develops in construction joints, expansion joints, settlement joints, and lining joints of tunnel and even around them; there is dotted water seepage, linear water seepage, and planar water seepage according to the trace and scope of water damage to tunnel lining. The result shows that water damage to loess double-arched tunnel mainly refers to linear water seepage, planar water seepage is also developed well, and partition and equipment box at the entrance and exit of tunnel are prone to water seepage; construction stage is crucial for controlling water damage to loess double-arched tunnel, atmospheric precipitation is the main water source, and the structure defect of double-arched tunnel increases the possibility of water seepage; the final sequence for weight of various factors is similar to the actual result

Experimental Free-Space Distribution of Entangled Photon Pairs over a Noisy Ground Atmosphere of 13km

We report free-space distribution of entangled photon pairs over a noisy ground atmosphere of 13km. It is shown that the desired entanglement can still survive after the two entangled photons have passed through the noisy ground atmosphere. This is confirmed by observing a space-like separated violation of Bell inequality of $2.45 \pm 0.09$. On this basis, we exploit the distributed entangled photon source to demonstrate the BB84 quantum cryptography scheme. The distribution distance of entangled photon pairs achieved in the experiment is for the first time well beyond the effective thickness of the aerosphere, hence presenting a significant step towards satellite-based global quantum communication.Comment: 4 pages, 3 figure

Genesis of the Yangjiakuang gold deposit, Jiaodong peninsula, China: Constraints from S-He-Ar-Pb isotopes, and Sm-Nd and U-Pb geochronology

Located in the Penglai-Qixia-Fushan Gold Belt, the Yangjiakuang gold deposit formed in the marble of the Paleoproterozoic Fenzishan Group is different from the previous altered rock-type gold deposits whose host gold-bearing rocks are Archean gneiss and Mesozoic granite. Two gold orebodies have been explored within the Yangjiakuang gold deposit, and both of them were controlled by the Yangjiakuang syncline. Three ore-forming stages have been recognized, including the pyrite-sericite stage (I), the gold, polymetallic sulfide, and quartz stage (II), and quartz-calcite stage (III). The calcites, which represent the main metallogenic stage (II) at Yangjiakuang gold deposit, yielded a Sm-Nd isochron age of 123.5 ± 8.1 Ma (MSWD = 0.042). Subsequent geologic events were recorded by quartz diorite porphyrite dyke which are dated at 122.75 ± 0.66 Ma (MSWD = 1.5) by zircon LA-ICP-MS U-Pb dating. It is suggested that the gold mineralization took place in the early period of Early Cretaceous. The in situ δ34S values of pyrites from two stages have a narrow range from + 5.65 to + 9.63‰ with an average value of 8.14‰, which indicate that the source of δ34S is related to the Guojialing granite and the Fenzishan Group. The lead isotopic compositions of pyrites (206Pb/204Pb = 16.615 to 16.832; 207Pb/204Pb = 15.275 to 15.403; 208Pb/204Pb = 36.829–37.470) show a consistent origin of the lower crust. The measured 3He/4He (40Ar/36Ar) of hydrothermal fluids in pyrites are 0.641–1.132 Ra (637.5–1162.7), indicating that the ore-forming fluid originating from a mixing of crustal and mantle components. It is suggested that the gold mineralization is associated with extensional tectonic inversion caused by the rollback of the subducting Izanagi Plate during the early Cretaceous, which triggered partial melting of mantle and lower crust, and subsequent magma mixing and exsolution of ore-bearing fluids. These fluids extracted ore-forming materials from the enclosing rocks of the Jiaodong Group, the Fenzishan Group, and the Guojialing granite to form the ore-forming fluids