Recently, researchers in the institute of solid state physics (ISSP), have succeeded in phase and energy band manipulation of a series of multinarymetal chalcogenidenanocrystals. The materials exhibit excellent electrocatalytic, thermoelectric, dielectric and NIR absorbing properties.
Multinary metal chalcogenides are one of research focuses of recent years, due to their important applications in the fields of photovoltaic cell, electrocatalytic system, thermoelectric conversion, photothermal usage, non-linear optics, optical storage and so on. Among these materials, copper zinc tin sulfide (Cu2ZnSnS4, simply as CZTS) and its derivatives are especially important considering their earth abundant composition for cost-effective solar cells, photo detectors and thermoelectric devices. However, multinary metal chalcogenides are usually accompanied during synthesis by binary or ternary impurities, which harm their performance. It is a great challenge for synthetic method to inhibit impurity formation and therefore guarantee the phase purity of product material with simultaneous size-tuning of nanocrystals. Moreover, applications of multinary metal chalcogenides in various fields such as photovoltaic cell and electrocatalytic system entail tunability of semiconductor band gap and position in certain range, which is challenging for material design.
Members in Professor ChanghuiYe¡¯s group, ISSP, have adopted a hot injection method to fabricate AgBiS2 and Cu3SbS3 nanocrystals. Through control of reaction dynamics, phase purity and size uniformity of the nanocrystals have been realized, and the nanocrystals have particular dielectric and NIR absorbing properties. The results have been published in CrystEngComm (CrystEngComm 15, 7644, 2013; CrystEngComm DOI:10.1039/C3CE41861H), one of the Royal Chemical Society journals.
To go a step further, through controllable element doping, the whole composition of Cu2ZnSn(S1-xSex)4, from CZTS to CZTSe, have been fabricated. The band positions of these CZTSSe nanocrystals have been systematically determined by experiment, which lays a good foundation for efficient solar cells (rainbow solar cells, for example) and catalytic systems. The result has been published in Scientific Reports (Scientific Reports 3, 2733, 2013), one journal of Nature Publishing Group. Three national invention patents based on the work have been accepted (201210124738.X, 201210156367.3, 201210294934.1).
All the research work is sponsored by National Basic Research Program of China, National Natural Science Foundation of China, and the Hundred Talent Program of the Chinese Academy of Sciences.
Figure: Multinary metal chalcogenide nanocrystals and band positions of CZTSSe nanocrystals.