Ruddlesden–Popper Perovskite for Stable Solar Cells

Three-dimensional metal-halide perovskites have emerged as promising light harvesting materials for converting sunlight to electricity in the last few years.High power conversion efficiency of 23.3%has been demonstrated.However,the main challenge that currently limits the application of the perovskite solar cells is the long-term stability,which has ambient,thermal,and photo stability weaknesses.

Facile deposition of high-quality Cs2AgBiBr6 films for efficient double perovskite solar cells

Lead-free double perovskite,Cs2AgBiBr6,with higher stability and lower toxicity than those of its lead counterparts,has been considered a promising alternative for next-generation photovoltaic materials.For practical applications,a facile deposition method that could be used to fabricate high-quality double perovskite films with large grain size is highly desired.However,such kind of facile method has never been established for Cs2AgBiBr6.Herein,high-quality Cs2AgBiBr6thin films with an average grain size of approximately 0.5μm were successfully deposited via a simple onestep spin-coating method by using dimethyl sulfoxide(DMSO)-N,N-dimethylformamide(DMF)mixture with optimized volume ratio as the solvent and chlorobenzene(CB)as the antisolvent.On the basis of satisfactory quality of the film efficient(>1%)Cs2AgBiBr6perovskite solar cells were constructed.Furthermore,the photo-generated charge-carrier transfer from Cs2AgBiBr6to the adjacent carrier extraction layers was systematically investigated via femtosecond transient spectroscopies.This study offers a new pathway to acquiring high-quality Cs2AgBiBr6thin films and provides a useful guide toward the development of high-efficiency double perovskite solar cells in the future.

Self-assembly Behavior of Metal Halide Perovskite Nanocrystals

The self-assembled metal halide perovskite(MHP)nanocrystal superlattices have attracted many researchers due to their exceptional optical and electrical properties.The bottom-up self-assembly can be facile to generate ideal and periodic structures.The superlattices’stability can be improved and the photoluminescence lifetime can be extended by an order of magnitude.However,due to lack of a comprehensive and systematic understanding of the internal interactions on self-assembled processes now,superlattices cannot be obtained controllably and play full use of their advantages.Therefore,gaining a deep insight of interaction forces about self-assemblies is the premise of designing and controlling the degree of self-assembly so as to prepare ideal materials.In this review,the definitions and functions of driving forces including van der Waals forces,electrostatic interactions and hydrogen bonds are discussed.Subsequently,we aim to explore the dominant factors affecting the driving forces,which can make a difference in the process of MHP self-assembly.Based on current researches,we emphasize on three aspects−the core of nanocrystals,surface ligands and solvents−to clarify their critical roles in controlling the driving forces.Finally,the outlooks and perspectives of how to facilitate the MHP self-assembly and their application on blue light emitting diodes are discussed.

Nonlinear finite element analysis of short-limbed wall

Combined with the actual project,this paper carries out a nonlinear finite element analysis on 2 groups,6 short-limbed shear walls,through the finite element calculation software ANSYS.The stress-strain relation of the models,and the effects of the type of sections and the axial compression ratios on the models can be obtained,providing a reference for future design.