An in-situ potassium (K)-doped copper–zinc–tin–sulfide (CZTS) precursor is prepared and annealed through selenization. After comprehensive optimization of the annealing, a cell with an efficiency of up to 12.62% is obtained,...
Alkali metal doping plays a great role in improving the efficiency of Cu2SnZn(S, Se)4 (CZTSSe) thin film solar cells. However, it is unclear how to realize the ideal distribution of alkali metal in CZTSSe films. Meanwhile, the mechanisms of alkali metal doping are still controversial. Herein, Na‐doped CZTSSe cells are fabricated by magnetron sputtering with Na‐containing Cu2SnZnS4 target which is in situ doping and annealing in selenization atmosphere. The incorporation of Na enhances the diffusion of K from the substrates to the absorbers. Na doping can increase the contact potential at the grain boundaries, which has beneficial effects on reducing the carrier recombination at the grain boundaries. Furthermore, Na incorporation modifies the conduction band offset at the CdS/CZTSSe interface from −0.07 to 0.03 eV. The defects and recombination in different regions are quantitatively extracted. It is demonstrated that the optimized grain boundary electrical properties and the heterojunction band alignment passivate the defects of the depletion region, the heterojunction interface, and the quasineutral region. Finally, a total‐area efficiency of 11.18% has been achieved in CZTSSe solar cell with an in situ Na doping concentration of 0.6 at%.
The ability to widely tune the optical properties of amorphous alloys is highly desirable especially for their potential applications in optoelectronic devices. In this work, we demonstrate that introducing oxygen into an amorphous alloy system of Co-Fe-Ta-B enables the formation of various amorphous derivatives ranging from metals to semiconductors, and eventually to insulators. These oxygencontaining amorphous derivatives gradually become transparent with the opened bandgaps, leading to a continuous increase in their optical transmittance. Furthermore, the reflective metal-type amorphous alloy and transparent insulator-type amorphous oxide of the system can be integrated together to realize the full-color tuning over the entire visible spectral range. This provides a new way to develop large-area color coatings with high design flexibility and full-color tunability. We envisage that the design concept proposed in this work is also applicable to many other amorphous alloy systems, from which all types of amorphous materials including alloys, semiconductors and insulators may be developed to show unprecedented optical functionalities.
The technological revolution, based on the big data, has exerted a huge impact on people's work and life styles. Currently, China has to simultaneously deal with the slowdown in economic growth, make difficult structural adjustments, and absorb the effects of previous economic stimulus policies, namely "the threestage superposition". In view of this, it is an inevitable way to use the big data to realize the economic transformation for the upgrading of resource-based cities. On this basis, by taking Jining City of Shandong Province as an example, this paper analyzes the economic development of resource-based cities, and discusses how to get an adequate understanding of the characteristics of the economic "new normal", how to adapt to "the new normal" from the stage characteristics of the current economic development, and how to use the big data technology to realize the transformation from the demand management to the supply management. With a commitment to put the structural adjustment in a more prominent position, and make good use of the decisive role of the market in the allocation of resources, it is urgent to take effective measures to encourage innovation, strengthen the training of the personnel, and develop the tertiary industry, so as to promote the overall upgrading of the industrial structure.
We developed a novel process for fabricating oxygen-rich Zn(O,S) buffer layers by magnetron reactive sputtering with a single oxygen-rich Zn(O,S) target, suitable for industrial all-dry production. Then, we successfully fabricated Cd-free Cu(In,Ga)(S,Se)2 (CIGSSe) solar cells. By varying the oxygen partial pressure during sputtering from 0 to 20%, we precisely controlled the Zn(O,S) composition, then systematically investigated its effects on the quality of oxygen-rich Zn(O,S) films, the properties of formed p–n junctions, and the performance of CIGSSe solar cells with Zn(O,S) buffer. We demonstrated that reactive sputtering with a Zn(O,S) target can generate a homogeneous, high-quality oxygen-rich Zn(O,S) buffer on large-area substrates. We observed a unique and unusual phenomenon: the appropriate content of secondary phase ZnSO4 and ZnSO3 improved the band alignment for oxygen-rich Zn(O,S). Combining our proposed schematic diagram of band alignmentat the Zn(O,S)/CIGSSe interface, we established a crucial correlation between the device performance and the interfacial properties at the p–n junction. For the CIGSSe device performance, the band alignment matching at the heterojunction plays a primary role, and the quality of oxygen-rich Zn(O,S) films plays a secondary role. Consequently, an excellent oxygen-rich Zn(O,S) buffer can be obtained with 10% Zn(O,S) deposition oxygen partial pressure , and the optimized device shows a higher V oc (447 mV) and a similar conversion efficiency (11.2%) than conventional CIGSSe devices with CdS buffer.
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