Stable and Highly Flexible Perovskite Solar Cells with Power Conversion Efficiency Approaching 20% by Elastic Grain Boundary Encapsulation

Here,we show that flexible perovskite solar cells(PSCs)with high operational stability and power conversion efficiency(PCE)approaching 20%were achieved by elastic grain boundary(GB)encapsulation.An introduction of trimethyltrivinylcyclotrisiloxane(V3D3)and solvent annealing(SA)resulted in an in situ cross-linking reaction between GBs and enlarged grain size that enabled oriented charge-transport properties to be achieved synchronously,leading to reduced sheet resistance with a high fill factor(FF)up to 82.93%in flexible PSCs.

Effect of Microdomain Structure on the Mechanical Behavior of Binary Blends

The relationship between microphase structure and mechanical response of the binary blends consisting of polystyrene-block-polyisoprene-block-polystyrene copolymer and low molecular weight polystyrene has been investigated. Low molecular weight polystyrene was chosen to obtain uniformly solubilized nano-blends without macrophase separation. The specimens were solution-cast by adding different amounts of homo-polystyrene to acquire different microphase structures. Small angle X-ray scattering（SAXS）, transmission electron microscopy（TEM） and atom force microscopy（AFM） have been used to study the microdomain and grain structure. It is observed that the structural changes in d-spacing and grain size on account of different amounts of polystyrene alter the mechanical behavior in both monotonic tensile and cyclic tests. The elastic and the Mullins effects are strongly sensitive to the changes in d-spacing and grain sizes. Moreover, the sample with bi-continuous structure shows the largest tensile strength and Mullins effect. In addition, the Mooneye-Rivlin phenomenological model was used to evaluate and explore the relationship between the polymer topological networks and the rubber elasticity of these styrenic nano-blends.