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Seminar Notice


Department of Chemistry
Multi-storey building
6th Floor
IIT Delhi
Tel: +91 11 2659 1501
        +91 11 2659 6599
Fax: +91 11 2658 1102


Department of Chemistry
Indian Institute of Technology Delhi

Synthesis, Assembly and Optoelectronic Applications of Branched Semiconductor Nanocrystals


Dr. Nimai Mishra

Department of Nanochemistry, Italian Institute of Technology-Genova, Italy

   Date  : April 20th 2017 (Thursday)   
                                                    Time  : 3:30 pm     
                                        Venue : Committee Room, Chemistry Department, 6th Floor

While conventional spherical colloidal nanocrystals have shown promise in these fields due to their ease of fabrication, processibility and salient optical properties, it may be envisaged that more applications may emerge if nanocrystals can be synthesized in shapes of higher complexity and therefore increased functionality. Here I will present a systematic, surfactant-driven hot injection method to synthesize CdSe seeded CdS nanoheterostructures with very high yield.1,2 This was extended to other systems such as CdSe/CdTe and CdTe/CdS or PbSe/PbS and Ag2Se/Ag2S via cation exchange techniques. I will discuss conditions in which the metal nanoparticle can be deposited precisely at the tip of one of four arms of tetrapods with symmetric reactivity.1 Afterward, I utilized these particles to overcome some of the key problems in the assembly of anisotropic shaped nanoparticles.2 CdSe/CdTe tetrapods immobilized on oleylamine-functionalized reduced graphene oxide (rGO) sheets can be homogeneously mixed with an organic dye (PCDTBT) to form donor–acceptor dispersed heterojunctions solar cell devices.3 Next, I will discuss a single active layer quantum dot light-emitting diode device based on colloidal CdSe (core)/CdS (arm) tetrapod nanostructures capable of simultaneously producing room temperature electroluminesence (EL) peaks at two spectrally distinct wavelengths, namely, at500 and660 nm.4 At the end I will discuss our recent investigation of single-tetrapod (single-emitter) level optical properties of CdSe/CdS tetrapods to reveal a strong blinking suppression and, in some structures, a unique two-color emission that can be blinking-free.6




            (1) Mishra et al. “Unusual Selectivity of Metal Deposition on Tapered Semiconductor Nanostructures.” Chem. Mater.    2012, 24 (11), 2040–2046.

            (2) Mishra, * et al. “Continuous Shape-Tuning of Nanotetrapods: Towards Shape Mediated Self-Assembly.” Chem.  Mater. 2016. 28 (4), 1187-1195 (* corresponding author)

            (3) Tong, S. W.; Mishra, N. et al. “High-Performance Hybrid Solar Cell Made from CdSe/CdTe Nanocrystals Supported on Reduced Graphene Oxide and PCDTBT.” Adv. Funct. Mater. 2014, 24 (13), 1904–1910.

            (4) Wong, J. I.*; Mishra, N.* et al. “Dual Wavelength Electroluminescence from CdSe/CdS Tetrapods.” ACS Nano 2014, 8 (3), 2873–2879. (* equal contribution)

(5) Mishra, * et al. “Cation Exchange Synthesis of PbSe/PbS Core/Shell Tetrapods and their Use as Near-   Infrared Photodetectors” Nanoscale, 2016,8, 14203-14212, (*corresponding author)

(6) Mishra et al. "Using shape to turn off blinking for two colour multiexciton emission in CdSe/CdS tetrapods" Nature Communications, 2017, Just accepted.

All are cordially invited to attend

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Department of Chemistry, Indian Institute of Technology Delhi