Riyanka Karmakar

@iiserb.ac.in

Senior Research Fellow, Department of Physics, Indian Institute of Science Education and Research Bhopal, 462066 India
Department of Physics, Indian Institute of Science Education and Research Bhopal, 462066 India

Riyanka Karmakar


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https://researchid.co/riyanka16
11

Scopus Publications

Scopus Publications

  • Multiple Carrier Generation at an Exceptionally Low Energy Threshold
    Riyanka Karmakar, Pravrati Taank, Debjit Ghoshal, Pushpendra Yadav, Dipendranath Mandal, et al.
    Physical Review Letters, 2025
  • Exciton many-body interactions and charge transfer in CsPbBr3 /graphene derivatives
    Naresh Chandra Maurya, Riyanka Karmakar, Rajesh Kumar Yadav, Pravrati Taank, Santu K. Bera, et al.
    Physical Review B, 2023
  • Exciton recombination in few-layer MoS2 nanosheets: Role of free carriers and defects
    Pravrati Taank, Riyanka Karmakar, K. V. Adarsh
    Surface and Interface Analysis, 2023
  • Defect-mediated carrier dynamics and third-order nonlinear optical response of WS2 quantum dots
    Riyanka Karmakar, Dipendranath Mandal, Megha Shrivastava, K. V. Adarsh
    Optics Letters, 2022
    In this Letter, we report the third-order absorptive and refractive nonlinear optical response of highly luminescent WS2 quantum dots (QDs) in the off-resonant femtosecond and nanosecond pulses, which is beneficial for optical limiting and quantum information processing. For 800 nm femtosecond excitation, QDs show two-photon absorption (β = (107 ± 2)×10−3 cm/GW) with positive nonlinearity originating from bound carriers. This picture changes significantly for 532 nm nanosecond excitation, where it shows reverse saturable absorption with negative nonlinearity primarily originating from the sequential absorption of two single photons through the shallow defects, creating free carriers. Our results provide a promising route toward low-dimensional optoelectronic devices.
  • An Insightful Picture of Multi-Particle Recombination in Few-Layer MoS2 Nanosheets
    Pravrati Taank, Riyanka Karmakar, Rituraj Sharma, Rajesh Kumar Yadav, Megha Shrivastava, et al.
    Journal of Physical Chemistry C, 2022
  • Third-Order Nonlinear Optical Response and Optical Limiting of WS2 Quantum Dots
    Optics Infobase Conference Papers, 2022
  • Trapped carrier hopping and unusual bottleneck in coalescence dynamics of MoS2few layers
    Riyanka Karmakar, Pravrati Taank, K. V. Adarsh
    Aip Conference Proceedings, 2021
    Unravelling the qualitative descriptions of ultrafast energy relaxation dynamics in transition metal dichalcogenides (TMDCs) is very important for the fundamental understanding of the nature of photoexcited carriers. Herein, we discuss the temporal evolution of B-exciton dynamics of colloidal MoS2 few layers by using femtosecond transient pump-probe absorption spectroscopy. We observe trapped carrier hopping and bimolecular recombination, which is portrayed as phonon-assisted coalescence through indirect bandgap at lower carrier-density and an unconventional bottleneck in decay kinetics above a critical density (⁓ 40 × 1013 cm-2). Also, we propose a new model describing the mechanistic origin of dynamical characterization of exciton relaxation with unprecedented carrier-densitydependent phenomena. This model is feasible to explain the physics behind the obscured nature of quenching of photoluminescence quantum yield of TMDCs and will provide powerful insight for fabricating defect-free optoelectronic devices in the near future.
  • Ultrafast Charge-Transfer Mediated Indirect-Excitons in CsPbBr3/MoS2Heterostructure
    2021 Conference on Lasers and Electro Optics CLEO 2021 Proceedings, 2021
  • Ultrafast charge-transfer mediated indirect-excitons in CsPbBr3/MoS2 heterostructure
    Optics Infobase Conference Papers, 2021
  • Unravelling the Role of Trap States on Carrier Dynamics of WS2 Quantum Dots
    Conference Proceedings Lasers and Electro Optics Society Annual Meeting LEOS, 2020
  • Unravelling the role of trap states on carrier dynamics of WS2 quantum dots
    Riyanka Karmakar, K.V. Adarsh
    Optics Infobase Conference Papers, 2020