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High quality CH 3 NH 3 PbI (3-x) Br x perovskite film with full surface coverage and fewer trap states was prepared using a single-step deposition process and PbBr 2 doped perovskite precursor solution. Specifically, the thin film surface becomes rougher and the grain size gets larger as the PbBr 2 concentration was increased from 1% to 10 mol%. Ultraviolet–visible spectroscopy (UV–vis) and incident photon-to-current efficiency (IPCE) spectra show that abnormal absorption onset shifts to longer wavelength with increasing the content of PbBr 2 , because the larger grain size can reduce the stress accumulated in the lattice over the Pb–I bond angle. It is surprising to see that when 5 mol% of PbBr 2 was used, the CH 3 NH 3 PbI 3 (MAPbI 3) shows the best thermal stability, with the decomposition onset increased by about 20 °C. The photoluminescence (PL) peak of the CH 3 NH 3 PbI (3-x) Br x film shifts to smaller wavelength as more PbBr 2 was used owing to decreased trap states in perovskite films. It is found that at the optimal PbBr 2 content of 5 mol%, the CH 3 NH 3 PbI (3-x) Br x based solar cell gives open-circuit voltage of 1.08 V with power conversion efficiency (PCE) as high as 18.97%, about 16.6% higher than the device based on the MAPbI 3 without Br. • Abnormal absorption onset shift of CH 3 NH 3 PbI 3 film by adding PbBr 2. • Enhancement the crystalline quality and grain size of the CH 3 NH 3 PbI (3-x) Br x film. • The highest PCE of CH 3 NH 3 PbI (3-x) Br x perovskite solar cell is 18.97%. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the shear capacity performance for eight deep beams with HTRB600 reinforced high strength concrete under concentrated load to enable a better understanding of the effects of shear span–depth ratio, longitudinal reinforcement ratio, vertical stirrup ratio and in order to improve design procedures. The dimension of eight test specimens is 1600 mm × 200 mm × 600 mm. The effective span to height ratio l0/h is 2.0, the shear span–depth ratio λ is 0.3, 0.6 and 0.9, respectively. In addition, the longitudinal reinforcement ratio ρs is set to 0.67%, 1.05%, 1.27%, and the vertical stirrup ratio is taken to be 0%, 0.25%, 0.33%, 0.5%. Through measuring the strain of steel bar, the strain of concrete and the deflection of mid-span, the characteristics of the full process of shear capacity, the failure mode and the load deflection deformation curve were examined. The test results showed that the failure mode of deep beams with small shear span–depth ratio is diagonal compression failure, which is influenced by the layout and quantity of web reinforcement. The diagonal compression failure could be classified into two forms: crushing-strut and diagonal splitting. With decreasing of shear span–depth ratio and increasing longitudinal reinforcement ratio, the shear capacity of deep beams increases obviously, while the influence of vertical web reinforcement ratio on shear capacity is negligible. Finally, the shear capacity of eight deep beams based on GB 50010-2010 is calculated and compared with the calculation results of ACI 318-14, EN 1992-1-1:2004 and CSA A23.3-04, which are based on strut-and-tie model. The obtained results in this paper show a very good agreement with GB50010-2010 and ACI 318-14, while the results of EN 1992-1-1:2004 and CSA A23.3-04 are approved to be conservative. [ABSTRACT FROM AUTHOR]