Organic–inorganic
perovskite solar cells have attracted significant attention due to
their remarkable performance. The use of alternative metal-oxide charge-transport
layers is a strategy to improving device reliability for large-scale
fabrication and long-term applications. Here, we report solution-processed
perovskite solar cells employing nickel oxide hole-extraction layers
produced in situ using an atmospheric pressure spatial atomic-layer
deposition system, which is compatible with high-throughput processing
of electronic devices from solution. Our sub-nanometer smooth (average
roughness of ≤0.6 nm) oxide films enable the efficient collection
of holes and the formation of perovskite absorbers with high electronic
quality. Initial solar-cell experiments show a power-conversion efficiency
of 17.1%, near-unity ideality factors, and a fill factor of >80%
with negligible hysteresis. Transient measurements reveal that a key
contributor to this performance is the reduced luminescence quenching
trap density in the perovskite/nickel oxide structure.
This article reports the synthesis of PEG-b-(PAA-g-PLA) amphiphilic brush polymers by the combination of RAFT polymerization and organocatalytic ROP, which could self-assemble into spheres for sustained release of doxorubicin.
The analysis of acoustic wave propagation in fluid-filled porous media based on Biot and homogenization theories has been adapted to calculate dispersion and attenuation of guided waves trapped in low-velocity layered media. Constitutive relations, the balance equation, and the generalized Darcy law of the modified Biot theory yield a coupled system of differential equations which governs the wave motion in each layer. The displacement and stress fields satisfy the boundary conditions of continuity of displacements and tractions across each interface, and the radiation condition at infinity. To avoid precision problems caused by the growing exponential in individual matrices for large wave numbers, the global matrix method was implemented as an alternative to the traditional propagation approach to determine the periodic equations. The complex wave numbers of the guided wave modes were determined using a combination of two-dimensional bracketing and minimization techniques. The results of this work indicate that the acoustic guided wave attenuation is sensitive to the in situ permeability. In particular, the attenuation changes significantly as the in situ permeability of the low-velocity layer is varied at the frequency corresponding to the minimum group velocity (Airy phase). Alternatively, the attenuation of the wave modes are practically unaffected by those permeability variations in the layer at the frequency corresponding to the maximum group velocity.
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