Influence of defect states on the performances of planar tin halide perovskite solar cells

Although tin halide perovskite has shown excellent photoelectric performance, its efficiency of solar cell is low compared with that of lead halide. In order to enhance the efficiency of tin halide perovskite solar cell, a deep understanding of the role of the defects in the perovskite absorption layer and at the electron transport layer(ETL)/absorber or absorber/hole transport layer(HTL) interface is very necessary. In this work, the planar heterojunction-based CH_3NH_3SnI_3 perovskite solar cells were simulated with the SCAPS-1D program. Simulation results revealed a great dependence of device efficiency on defect density and interface quality of the perovskite absorber. The defect density at the front interface is critical for high efficiency, and the polarity of the interface charge has a different impact on the device efficiency. Strikingly, an efficiency over 29% was obtained under the moderate simulation conditions.

Time-dependent evolution process of Sb_2Te_3 from nanoplates to nanorods and their Raman scattering properties

High-quality SbTenanostructures are synthesized by a simple hydrothermal method. The morphologies of the nanostructures change from hexagonal nanoplates to nanorods with the extension of growth time. Secondary nucleation is the dominant factor responsible for the change of the morphologies. Structural analyses indicate that all the obtained nanostructures are well crystallized. IR-active phonons are mainly observed in the Raman spectra of the nanoplates and nanorods. The slight deviations are observed in the Raman modes between the nanoplates and nanorods, which could originate from confinement effect in the nanostructures.

Annealing-enhanced interlayer coupling interaction in GaS/MoS2 heterojunctions

Fabrication of large-area atomically thin transition metal dichalcogenides is of critical importance for the preparation of new heterojunction-based devices.In this paper, we report the fabrication and optical investigation of large-scale chemical vapor deposition(CVD)-grown monolayer MoS2 and exfoliated few-layer GaS heterojunctions.As revealed by photoluminescence(PL) characterization, the as-fabricated heterojunctions demonstrated edge interaction between the two layers.The heterojunction was sensitive to annealing and showed increased interaction upon annealing at 300℃ under vacuum conditions, which led to changes in both the emission peak position and intensity resulting from the strong coupling interaction between the two layers.Low-temperature PL measurements further confirmed the strong coupling interaction.In addition, defect-related GaS luminescence was observed in our few-layer GaS, and the PL mapping provided evidence of edge interaction coupling between the two layers.These findings are interesting and provide the basis for creating new material systems with rich functionalities and novel physical effects.

Reduced graphene oxide-based calcium alginate hydrogel as highly efficient solar steam generation membrane for desalination

Solar-driven evaporation has been considered as one of the potentialmethods for desalination and sewage treatment.However,optical concentrators andcomplex multi-component systems are essential in advanced technologies,resulting inlow efficiency and high cost.Here,we synthesize a reduced graphene oxide-basedporous calcium alginate(CA-rGO)hydrogel which exhibits good performance in lightabsorption.More than 90%of the light in the whole spectrum can be absorbed.Meanwhile,the water vapor escapes from the CA-rGO film extremely fast.The waterevaporation rate is 1.47 kg·m^(-2)·h^(-1),corresponding to the efficiency 77%under only 1 kW'm 2 irradiation.The high evaporation efficiency is attributed to the distinctive structureof the film,which contains inherent porous structure of hydrogel enabling rapid watertransport throughout the film,and the concave water surfaces formed in the hydrophilicpores provide a large surface area for evaporation.Hydrophobic rGO divides theevaporation surface and provides a longer three-phase evaporation line.The test onmultiple cyclic radiation shows that the material has good stability.The CA-rGO hydrogelmay have promising application as a membrane for solar steam generation indesalination and sewage treatment.