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HELLO! I'M Uday.

Udayabhaskararao Thumu joined INL in 2017 and he is currently working as a Research Fellow through Marie Curie action (NanoTRAINforGrowth II) and studying the optical properties of nanodevices based on colloidal semiconductor and perovskite nanocrystals for photovoltaic applications.

 

 
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About Uday 

Udayabhaskararao Thumu joined INL in 2017 and he is currently working as a Research Fellow through Marie Curie action (NanoTRAINforGrowth II) and studying the optical properties of nanodevices based on colloidal semiconductor and perovskite nanocrystals for photovoltaic applications.

Prior to joining INL, in Braga, his postdoctoral research focused on the thermodynamic control of phase transformations and photophysics of perovskite nanocrystals at Department of Physics of Complex System, Weizmann Institute of science, Israel. His first postdoctoral research was conducted at the Department of Organic Chemistry, Weizmann Institute of Science on the self-assembly of binary nanocrystals and the post modifications for bottom-up nanofabrication. He also experienced in noble metal nanocluster research, synthesis & characterisations and their catalytic, sensing applications during his doctoral research at Indian Institute of technology Madras, India. Prior to joining Ph.D, he completed his Master’s degree in Chemistry from Andhra University, Vishakhapatnam, India.

 

 

The Cofund project

Creation of new materials always fascinates researchers as it provides immense opportunities to scientific understanding and technological advancement. In this project, we aim to fabricate and investigate novel hybrid nanomaterials. Hybrid materials, consisting of two components having significantly different physical properties, often exhibit emergent properties which are absent in either one of the separate components. Colloidal semiconductor quantum dots (QDs) and cesium lead halide perovskite nanocrystals (CsPbX3 NCs, X = Cl, Br, I)) are two classes of novel materials. Semiconductor QDs have been intensively studied in the last few years in various contexts, ranging from fundamental optical properties to device engineering. On the other hand, CsPbX3 NCs are the newest addition to the family of organic‒inorganic perovskite materials. My research involves the development ofmethodologies to couple QD and perovskite interfaces and unifying them as one material and study their interesting optical properties. This research aims to reduce non-radiative recombination processes in nanocrystal solids to enhance charge-carrier separation and potential applications in solar light harvesting.

Selected publications:

1. Udayabhaskararao T.; Altantzis T.; Lothar H.; Marc C.; Judith L.; Ronit P.; Liz-Marzán L. M.; Lela V.; Petr K.; Sara B.; Rafal K.; Science 2017, 358, 514-518.

2. H. Zhao, S. Sen, Udayabhaskararao, T.; M. Sawczyk, K. Kučanda, D. Manna, P. K. Kundu, J.-W. Lee, P. Král, R. Klajn, Nature Nanotech. 2015, 11, 82.

3. Kundu, P. K.; Leizrowice, R.; Margulis, B.; Borner, M.; Hui, Z.; Udayabhaskararao, T. Rafal, K. Nature Chem. 2015, 7, 646.

4. Udayabhaskararao, T.; Pradeep, T. Angew. Chem. Int.Ed. 2010, 49, 3925.

5. Udayabhaskararao, T.; Nataraju, B.; Pradeep, T. J. Am. Chem. Soc. 2010, 132, 16304.

6. Udayabhaskararao, T.; Sun, Y.; Goswami, N.; Pal, S. K.; Balasubramanian, K.; Pradeep, T. Angew. Chem. Int. Ed. 2012, 51, 2155.

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Mixed-dimensional Perovskites

The estimated global lighting energy bill has reached totalling approximately $230 billion per year and worldwide, lighting accounts 20% of total electricity production. Perovskite and related materials are newly developing as promising materials for white LED chip driving luminescent materials. For example, even at its early stages of research, the green-emitting three dimensional (3D) CsPbBr3 perovskite nanocrystal (NCs) based LED device has achieved record-breaking external quantum efficiency, EQE, of 10.43%. The perovskite NCs are highly crystalline and typically available in cube structure (Figure 1a). Despite the rising interest, the stability of these NCs is much poorer than that of the commercially available phosphors or QDs. Their inherent poor stability at ambient atmospheric conditions such as exposure to oxygen, light, variable humidity, solvent dilutions, and temperature. Such conditions can cause drastic PL quenching and phase transitions. The reason for their instability is due to their ionic character, labile surfaces, and metastable structures. The superior photophysical properties of perovskite NCs can be further improved through surface treatment strategies. Immobilized inorganic passivation could graft better than organic passivation for effective stabilization of CsPbBr3 NCs. In my research, I have developed hybrid structures of 3D CsPbBr3 NCs nucleates within the Cs4PbBr6 crystals (Figure 1b) through simple wet chemical procedures.  It is worth noting that the Cs4PbBr6 is a large band gap (≈3.9 eV) semiconductor or an insulator and CsPbBr3, with a bandgap of about 2.48 eV (Figure 1c).  The high band gap Cs4PbBr6 matrix cannot act as effective recombination centers which can result in high efficient light emission from CsPbX3 NCs within the hybrid structures. As a result, photoluminescence quantum yield, stability, and device performance can increase substantially. Photophysical properties of these hybrid structures and the device performance is currently in progress.

  Figure 1.  (a)  High - angle annular dark - field scanning transmission electron microscopy  (HAADF-STEM) image of perovskite NCs. (b) STEM analysis showing hybrid nanostructures composed of 3D perovskites (CsPbBr3) in OD perovskite matrix (Cs4PbBr6). High-contrast particles in the dotted circle represent the 3D perovskite and the rest of lattice corresponds to 0D perovskite matrix. (c) Absorption spectra of 0D and 3D perovskite structures with different band gaps.

Figure 1. (a) High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of perovskite NCs. (b) STEM analysis showing hybrid nanostructures composed of 3D perovskites (CsPbBr3) in OD perovskite matrix (Cs4PbBr6). High-contrast particles in the dotted circle represent the 3D perovskite and the rest of lattice corresponds to 0D perovskite matrix. (c) Absorption spectra of 0D and 3D perovskite structures with different band gaps.