The shape-controlled synthesis of alloyed CdS_xSe_1−x nanocrystals and their applications in LEDs

Abstract

Alloy nanocrystals (NCs) provide access and control of the parameters for nanoscale engineering because their physical and optical properties depend on size, shape, and composition. Here, alloy CdS x Se1−x NCs with different shapes were synthesised via a one-pot method using cadmium acetate, sulfur, and selenium as precursors in trioctylphosphine solution. The luminescence and shapes of NCs were characterised by fluorescence spectroscopy and transmission electron microscopy, respectively. It was found that the modification of precursor concentration resulted in NC shape variation, including branched NCs, long and short nanorods. Consequently, a series of alloy CdS x Se1−x NCs with different shape-based light emitting devices (LEDs) were fabricated and their operation characteristics were also compared. The obtained luminance and luminous efficiency showed that the control of NC shape is the key factor for the improvement of LED performance. We anticipate that this work will provide further insight into the design of CdSxSe1−x NCs-based LEDs with shape variation.

Colloidal semiconductor nanocrystals: from bottom-up nanoarchitectonics to energy harvesting applications

“…49 This approach has been successful in producing alloyed nanocrystals of CdS x Se 1Àx , CdSe x Te 1Àx , and CdS x Te 1Àx . 49,132 Our group demonstrated the synthesis of high quality homogeneous CuCdS alloyed NCs using colloidal hot injection synthesis route. 41 The fabrication of high-efficiency light emitting diodes using CuCdS alloyed NCs as an active layer were demonstrated.…”

“…49 The exact structure of the alloy is highly dependent on the reactivity of the precursors. 49,132,163 The synthesis of CdSe x S 1Àx alloyed NCs via successive ionic layer adsorption and reaction (SILAR) method was reported for photovoltaic applications. 164 A noninjection route has also been shown to be effective for synthesizing CdSe 0.45 Te 0.55 NCs, leading to reasonable photovoltaic performance.…”

“…328 We have demonstrated that a large Stokes shift can also be obtained by designing suitable alloyed NCs. 49,132 Such allowed NCs of CuCdS NCs showed excellent emitting properties when used as an active layer in the LEDs. 41 Simple device architecture contained orange color emitting CuCdS NCs as an active layer, which was sandwiched between the TPD/PEDOT:PSS-coated indium tin oxide (ITO) anode and ZnO/Al cathode (Fig.…”