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Semi-transparent perovskite solar cells are highly attractive for a wide range of applications, such as bifacial and tandem solar cells; however, the power conversion efficiency of semi-transparent devices still lags behind due to missing suitable transparent rear electrode or deposition process. Here we report a low-temperature process for efficient semi-transparent planar perovskite solar cells. A hybrid thermal evaporation–spin coating technique is developed to allow the introduction of PCBM in regular device configuration, which facilitates the growth of high-quality absorber, resulting in hysteresis-free devices. We employ high-mobility hydrogenated indium oxide as transparent rear electrode by room-temperature radio-frequency magnetron sputtering, yielding a semi-transparent solar cell with steady-state efficiency of 14.2% along with 72% average transmittance in the near-infrared region. With such semi-transparent devices, we show a substantial power enhancement when operating as bifacial solar cell, and in combination with low-bandgap copper indium gallium diselenide we further demonstrate 20.5% efficiency in four-terminal tandem configuration. Perovskite solar cells already exhibit large efficiencies above 20%. Here, the authors use a low temperature sputtering process to fabricate semi-transparent perovskite solar cells, demonstrating bifacial operation and a 4-terminal tandem with CIGS solar cells surpassing single junction cells.

The knowledge of minority carrier lifetime of a semiconductor is important for the assessment of its quality and design of electronic devices. Time-resolved photoluminescence (TRPL) measurements offer the possibility to extract effective lifetimes in the nanosecond range. However, it is difficult to discriminate between surface and bulk recombination and consequently the bulk properties of the semiconductor cannot be estimated reliably. Here we present an approach to constrain systematically the bulk and surface recombination parameters in semiconducting layers and reduces to finding the roots of a mathematical function. This method disentangles the bulk and surface recombination based on TRPL decay times of samples with different surface preparations. The technique is exemplarily applied to a CuInSe 2 and a back-graded Cu(In,Ga)Se 2 compound semiconductor, and upper and lower bounds for the recombination parameters and the mobility are obtained. Sets of calculated parameters are extracted and used as input for simulations of photoluminescence transients, yielding a good match to experimental data and validating the effectiveness of the methodology. A script for the simulation of TRPL transients is provided.

Cu(In,Ga)Se 2 -based solar cells have reached efficiencies close to 23%. Further knowledge-driven improvements require accurate determination of the material properties. Here, we present refractive indices for all layers in Cu(In,Ga)Se 2 solar cells with high efficiency. The optical bandgap of Cu(In,Ga)Se 2 does not depend on the Cu content in the explored composition range, while the absorption coefficient value is primarily determined by the Cu content. An expression for the absorption spectrum is proposed, with Ga and Cu compositions as parameters. This set of parameters allows accurate device simulations to understand remaining absorption and carrier collection losses and develop strategies to improve performances.

Cu(In,Ga)Se based solar cells have reached efficiencies close to 23%. Further knowledge-driven improvements require accurate determination of the material properties. Here, we present refractive indices for all layers in Cu(In,Ga)Se solar cells with high efficiency. The optical bandgap of Cu(In,Ga)Se does not depend on the Cu content in the explored composition range, while the absorption coefficient value is primarily determined by the Cu content. An expression for the absorption spectrum is proposed, with Ga and Cu compositions as parameters. This set of parameters allows accurate device simulations to understand remaining absorption and carrier collection losses and develop strategies to improve performances.

Calibration of flow devices is important in several areas of pharmaceutical, flow chemistry and microfluidic applications where dosage of process liquids or accurate measurement of flow rate is important. The process-oriented liquid itself might influence the performance of a flow device and the simultaneous determination of dynamic viscosity under flow conditions might provide valuable information for process parameters. To offer simultaneous calibration of the dynamic viscosity of a process-oriented liquid at the corresponding flowrate, METAS built a pipe viscometer for the traceable inline measurement of dynamic viscosity in current flow facilities for low flowrates from 1 μL/min to 150 mL/min and pressure drops up to 10 bar. The traceability of all measuring quantities as well as geometrical dimensions of the microtube guarantee the traceability of the pipe viscometer to SI units. The most challenging part is the traceable determination of the inner diameter of the microtube. This can be achieved by measuring the pressure drop as a function of flowrate using a pipe viscometer and applying the Hagen–Poiseuille law with a traceable dynamic viscosity of a reference liquid (water) or performing measurements by utilizing the μ-CT facility at METAS, where the inner diameter is determined using X-ray diffraction. The validation of the stated measurement uncertainty of the pipe viscometer was performed by calibrating the dynamic viscosity of several reference liquids with traceable density and kinematic viscosity. The setup of the facility, traceability as well as uncertainty calculation of the pipe viscometer for inline measurement of dynamic viscosity are discussed in this paper.

A 36-year-old man was treated with two intraarticular corticoid injections for intense pain and severely decreased range of motion of his left shoulder. After the second injection, he came back with fulminant arthritis. Microbiological examination revealed streptococcus pneumoniae. Open debridement, long-term antibiotics, and total shoulder replacement were necessary to restore acceptable shoulder function. The fulminant course with rapid destruction of the joint illustrates the risks of intraarticular corticoid injections. This case also shows that the diagnosis should be accurately made and risk factors excluded before considering injection as a treatment.