Introduction Of Interfacial Layer Research Articles

Current Status and Future Prospects of Kesterite Cu2ZnSn(S,Se)4 (CZTSSe) Thin Film Solar Cells Prepared via Electrochemical Deposition

AbstractThe fabrication of kesterite Cu2ZnSn(S,Se)4 (CZTSSe) thin‐film solar cells using the electrochemical deposition (ED), which is valued for its industrial feasibility, offers a cost‐effective and environmentally friendly approach to the carbon‐free and clean energy production. However, the reported power conversion efficiency of approximately 10 % for electrodeposited CZTSSe thin‐film solar cells is lower compared to the alternative methods like sputtering and spin‐coating, which is mainly attributed to the phase inhomogeneity and the rough morphology generated during the ED process. Ensuring the microscopic and macroscopic uniformity of the electrodeposited films is crucial for the improvement of the film quality and the device performances. In this review, strategies to address these challenges including the intrinsic film control such as the deposition mode, pH, concentration of metal ions, and complexing agents, as well as the extrinsic approaches such as doping, substitution of metal elements, and the introduction of interfacial layers. In addition, the prospects for the electrochemically deposited CZTSSe solar cells were presented, focusing on the promising applications in tandem, flexible, and solar water‐splitting devices. Finally, this review will provide technical insights into the ED process for preparing CZTSSe solar cells, outlining a perspective for the future development of highly efficient CZTSSe thin film solar cells.

A New Interfacial Model for Transverse Mechanical Properties of Unidirectional Fiber Reinforced Composites

Transverse mechanical properties play an important role in the study of fiber reinforced composite materials. An experimental and numerical study on mechanical properties and damage behavior of unidirectional fiber reinforced composites under transverse load is presented. The quasi-static tensile and compressive tests were carried out to obtain mechanical properties of unidirectional fiber reinforced composites under transverse tension and compression. The fracture morphologies of the specimens were observed by scanning electron microscopy (SEM) to reveal their distinct damage mechanism. Considering the effects of interface, a new interfacial model is proposed. Two representative volume elements (RVEs) of basic and interfacial models are established for comparison analysis. The predicted results agree well with the experimental data. The introduction of interfacial layer has little effect on the prediction of transverse modulus, but can improve the accuracy of the predicted transverse strength. The fiber volume fraction has a great influence on the transverse mechanical properties of unidirectional fiber reinforced composites. As the fiber volume fraction increases, its transverse modulus increases, but both the transverse strength and the ultimate strain decrease.

Enhancing both strength and toughness of carbon/carbon composites by heat-treated interface modification

A simple method to increase both strength and toughness of carbon/carbon (C/C) composites is presented. This method is based on the heat treatment of the pre-deposited thin carbon coating, leading to the formation of more orderly pyrolytic carbon (PyC) as a functional interlayer between fiber and matrix that could optimize the interfacial sliding strength in C/C composites. Effects of such a heat-treated PyC layers on the microstructure, tensile strength and fracture behavior of unidirectional C/C composites were investigated. Results showed that although the in-situ fiber strength was deteriorated after the introduction of interfacial layer, tensile strength of the specimen was greatly improved by 38.5% compared with pure C/C composites without any treatment. The interfacial sliding stress sharply decreased, which was interpreted from finite element analysis and verified by Raman spectra. Therefore, the fracture behavior was changed from brittle fracture to multiple-matrix cracking induced non-linear mechanical behavior. Finally, the ultimate strength can be predicted by different models according to the interfacial sliding stress. Our research would provide a meaningful way to improve both strength and toughness of C/C composites.

Stability of Polymer Solar Cells

Organic photovoltaics (OPVs) evolve in an exponential manner in the two key areas of efficiency and stability. The power conversion efficiency (PCE) has in the last decade been increased by almost a factor of ten approaching 10%. A main concern has been the stability that was previously measured in minutes, but can now, in favorable circumstances, exceed many thousands of hours. This astonishing achievement is the subject of this article, which reviews the developments in stability/degradation of OPVs in the last five years. This progress has been gained by several developments, such as inverted device structures of the bulk heterojunction geometry device, which allows for more stable metal electrodes, the choice of more photostable active materials, the introduction of interfacial layers, and roll-to-roll fabrication, which promises fast and cheap production methods while creating its own challenges in terms of stability.