Polytypic Zn–(In,Ga)–Se Nanocrystals with Tunable Emission

While the polymorphism of chalcopyrite semiconductors has been widely studied, the wurtzite analogues of defect-chalcopyrite II-III2-VI4 compositions, such as Zn(In,Ga)2(S,Se)4, remain underexplored. Here, we report the synthesis of polytypic Zn-(In,Ga)-Se multipods via cation exchange using ZnSe as a template. With zinc-blende cores and wurtzite arms elongated along the hexagonal c-axis, the multipods retain the structure and morphology of the ZnSe template. Optical characterization reveals composition-dependent absorption and photoluminescence, tunable from the visible to the near-infrared region, with spectral features distinct from those of previously reported defect-chalcopyrite structures. Temperature-dependent measurements demonstrate strong emission at cryogenic temperatures, which is quenched near room temperature due to thermally activated nonradiative processes. We illustrate the use of ZnSe as a platform for cation exchange toward wurtzite multinary chalcogenides, unlocking access to novel structures with colorful optical properties.