Synthesis and Micrometer-Scale Assembly of Colloidal CdSe/CdS Nanorods Prepared by a Seeded Growth Approach

Abstract

Key limitations of the colloidal semiconductor nanorods that have been reported so far are a significant distribution of lengths and diameters as well as the presence of irregular shapes produced by the current synthetic routes and, finally, the poor ability to fabricate large areas of oriented nanorod arrays. Here, we report a seeded-growth approach to the synthesis of asymmetric core-shell CdSe/CdS nanorods with regular shapes and narrow distributions of rod diameters and lengths, the latter being easily tunable up to 150 nm. These rods are highly fluorescent and show linearly polarized emission, whereby the emission energy depends mainly on the core diameter. We demonstrate their lateral alignment as well as their vertical self-alignment on substrates up to areas of several square micrometers.

Colloidal Quantum Nanostructures: Emerging Materials for Display Applications

“…The mixed 0D/1D CdSe/CdS dot‐in‐rod heterostructure discussed above is an interesting case in this context 83. It showed linearly polarized emission along its elongated axis, which was directly confirmed by using combined optical and atomic force microscopy to correlate the emission polarization with the orientation of single seeded nanorods (Figure 6 c) 86.…”

“…In 2003 a dot‐in‐rod architecture of a CdSe dot within a CdS rod was introduced,82 and later a seeded growth synthesis for this interesting system was reported 83, 84. This CdSe/CdS dot‐in‐rod heterostructure system has a mixed dimensionality as it integrates a 0D confined seed within a 1D confined system.…”

Nearly Temperature‐Independent Threshold for Amplified Spontaneous Emission in Colloidal CdSe/CdS Quantum Dot‐in‐Rods

“…[ 14 ] The optical and structural properties of the samples investigated are summarized in Table 1 . The core size (diameter) was varied from 2.2 nm to 3.3 nm.…”

“…The growth of the CdS shell provides surface passivation of the core and reduces the amount of surface defects, resulting in quasi type-II Qdots with high photoluminescence quantum effi ciency. [ 14 ] Additionally, it allows further extending the ASE spectral range as ASE in these systems can arise either from the core or the shell. [ 15 ] Indeed, Table 1 and Figure 1 (b) show that, by careful selection of the core and shell dimensions, the ASE can be tuned from a wavelength λ of 475 nm to 610 nm.…”

Type-tunable amplified spontaneous emission from core-seeded CdSe/CdS nanorods controlled by exciton–exciton interaction

“…With advances in the colloidal synthesis of CdSe/CdS core/shell NRs, it is possible to synthesize highly efficient and crystalline CdSe/CdS core/shell NRs having a narrow size distribution by nely controlling their shape and size. 15,16 Furthermore, due to shallow band offset for electrons in the CdSe/CdS core/shell material system, a partial separation of electron and hole wavefunctions is observed which is known as the quasi type-II electronic structure that contributes to the suppression of Auger recombination, which is highly critical for achieving lasing. 11,[16][17][18] The other advantage of having a lower energy barrier for electrons in CdSe/CdS NRs is that, by simply changing their core and shell sizes, it is possible to tailor the electron and hole wavefunction overlap and tune CdSe/CdS NRs from type-I-like to quasi-type-II-like band alignment, which can be an important design consideration when engineering the gain/loss mechanisms in practical lasing systems.…”