NEWS
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Congratulations Santu!!! Eighth Dr. from the group (February 2024 ).
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Congratulations Riyanka for winning the Best Thesis Award from INYAS Saransh! (1st prize)
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Congratulations Ajay for the Publication in Phys. Rev. Letters. (Jan, 2024)
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Congratulations Afreen for receiving PMRF fellowship (2023).
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Congratulations Naresh & Riyanka for the Publication in Phys. Rev. B. (Oct, 2023).
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Congratulations Riyanka for winning KVRSS Research Award 2023!! (Silver Medal).
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Congratulations Ajay for the Publication in Phys. Rev. Applied Letters. (Aug, 2023)
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Congratulations Ankit for achieving JSAP-Optica Travel Award (2023).
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Congratulations Pravrati for receiving SERB Travel Grant for ICMAT Singapore 2023.
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Congratulations Vinod for receiving CSIR Travel Grant for ICMAT Singapore 2023.
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Congratulations Dipendranath!!! Seventh Dr. from the group (May, 2023 ).
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Congratulations Vinod & Dipendranath for the publication in Phys. Rev. Applied.
OUR LATEST RESEARCH
Superfluorescence from Electron-Hole Plasma at Moderate Temperatures of 175 K
Recently, We report the first experimental observation of superfluorescence from the EHP in a coupled CsPbBrI2 quantum dots film via intense near-band gap excitation without any external stimuli even at temperatures of 175 K.
[Ajay K Poonia et. al., Phys. Rev. Lett. 132, 063803 (2024)]
Intervalley polaronic biexcitons in metal halide perovskite quantum dots
The strong band edge exciton-phonon interactions in metal halide perovskite quantum dots (QDs) offer a unique platform to explore many-body phenomena. Employing CsPbBr3 QDs as a perovskite model system, we report the observation of spin-selective polaronic biexcitons using collective excitations of two circularly polarized ultrafast lasers of a duration that is two orders of magnitude shorter than the exciton lifetime and one order of magnitude shorter than the spin relaxation time. The intervalley polaron pairing of charge carriers determines the anomalously strong exciton-exciton interactions, where the Haynes factor is an order of magnitude larger than the bulk and five times larger than the two-dimensional and quantum well semiconductors, demonstrating a very robust correlation of excitons. Our findings reveal a mechanism of generating highly stable biexciton states even at room temperature to realize higher-order correlations of charge carriers such as quantum droplets and Bose-Einstein condensates.
[Ajay K. Poonia et. al., Phys. Rev. B Lett. 104, L161407 (2021)]
Novel heterostructures with enhanced nonlinear optical response
The nonlinear optical absorbance of conventional materials is very weak, yet its magnitude dominates device performance in, for example, optical limiting and pulse shaping. Therefore, achieving a strong nonlinear optical response is a longstanding goal. We propose charge transfer between donor and acceptor materials as a means to greatly enhance nonlinear response, toward the realization of high-performance optical limiters. Excellent agreement between experiment and theory for a test hybrid material validates the idea, and guides the design and fabrication of an actual liquid-cell-based absorptive optical limiter, which outperforms benchmark devices.
[R. Yadav et. al., Phys. Rev. Applied 9, 044043 (2018)]
Exciton many body interactions in colloidal perovskite nanocrystals
Exciton many body interactions is the fundamental light–matter interaction which determines the optical response of the new class of colloidal perovskite nanocrystals of the general formula CsPbX3 [X = Cl or Br or I]. However, the understanding of exciton many body interactions manifested through the transient bi-excitonic Stark effect at the early time scales and the Auger recombination process in this new class of materials still remain rather incomplete. We are focussing on the many body exciton interactions under controlled conditions through ultrafast transient absorption spectroscopy. A large bi-excitonic redshift ∼30 meV to the effect of hot excitations on the excitonic resonance is observed at the early timescales. Fluence dependent studies show two-fold degenerate band edges. This explicit experimental evidence for the exciton many-body interactions in CsPbBr3 nanocrystals provides a powerful tool to explore the development of their prospective applications in light emitting devices, lasers, and solar cells.
[Aneesh J. et. al., J. Phys. Chem. C, 121 4734 (2017) ]