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Mukherjee S, Ghosh S, Biswas D, Ghosal M, De K, Mandal PK. Transforming exciton dynamics in perovskite nanocrystal through Mn doping. NANOSCALE 2023; 15:6947-6953. [PMID: 36974486 DOI: 10.1039/d3nr00241a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Zn-alloyed CsPb(Cl/Br)3 perovskite nanocrystals (PNCs) have been synthesized and used as a model system for Mn doping in order to understand the effect of Mn doping on exciton dynamics. While keeping the PL emission maximum and PLQY of both PNC samples nearly the same, the radiative decay rate of the host band decreases ∼6.5 times and the non-radiative decay rate increases ∼2.5 times upon Mn doping. Unlike reports in the literature in which the dopant emission decreases to near-zero, in the present case we observe ∼5.5-fold enhancement of the integrated PL intensity of the dopant emission when the temperature decreases from 290 K to 190 K. Interestingly, the FWHM of the host PL emission band increases with a decrease in temperature from 290 K to 190 K. A higher value of phonon energy in PNC2 (58 ± 2 meV) in comparison to CsPbBr3 has been noted. The low magnitude of the Huang-Rhys factor indicates less electron phonon coupling for the Mn-doped PNC system. Temperature-dependent dopant PL decay exhibits biexponential decay behaviour with time constants τ1 = 450-540 μs and τ2 = 1.1-1.2 ms. With a decrease in temperature from 290 K to 190 K, the amplitude of the faster component decreases from 80% to 60%; concomitantly, the amplitude of the slower component increases from 20% to 40%. Ultrasensitive single-particle spectroscopic analyses reveal that, although the probability density distributions (PDDs) of the durations of both ON and OFF events of PNC1 could be fitted with a truncated inverse power law (TIPL), however, for PNC2, both PDDs could be fitted with an inverse power law (IPL). A comparatively lower value of the power law exponent mON indicates a higher probability of longer ON events for PNC1 than for PNC2. Truncation in the PDDs of both ON and OFF events has been observed for PNC1, but not in the PDDs of either ON or OFF events for PNC2. The presence of shallow trap states is responsible for the truncation for PNC1, whereas the presence of deep dopant states does not allow truncation in the host PL emission of PNC2. All these observations clearly demonstrate that Mn doping transforms the host PL exciton dynamics for Zn-alloyed Mn-doped CsPb(Cl/Br)3 PNCs very significantly.
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Affiliation(s)
- Soumen Mukherjee
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
| | - Swarnali Ghosh
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
| | - Dibyendu Biswas
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
| | - Mainak Ghosal
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
| | - Kheyali De
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
| | - Prasun K Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
- Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India.
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Ghosh S, Mukherjee S, Mandal S, De CK, Mardanya S, Saha A, Mandal PK. Beneficial Intrinsic Hole Trapping and Its Amplitude Variation in a Highly Photoluminescent Toxic-Metal-Free Quantum Dot. J Phys Chem Lett 2023; 14:260-266. [PMID: 36595225 DOI: 10.1021/acs.jpclett.2c03373] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Intrinsic hole trapping as well as hole detrapping have not been observed for any quantum dot (QD) or perovskite nanocrystal (PNC) system. Moreover, amplitude variation of intrinsic hole trapping (or detrapping) has not been reported at all for any QD or PNC system. However, for a CuInS2-based core/alloy-shell (CAS) QD system, (a) both intrinsic hole trapping and detrapping have been observed and (b) very significant amplitude variations of hole trapping (∼16 to ∼42%) and hole detrapping (∼44 to 23%) have been observed. Unlike detrimental electron trapping, hole trapping has been shown to be beneficial, having a direct correlation toward increasing PLQY to 96%. Simultaneous electron and hole trapping has been shown to be quite beneficial for the CuInS2-based CAS QD system leading to the longest ON time (∼130 s) for which a nontoxic metal-based QD remains only in the ON-state without blinking.
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Divya P, Anagha G, Nharangatt B, Chatanathodi R, Sabrin H, Nourin N, Fausia KH, Padmakumar K, Jose D, Sandeep K. Anion Exchange Reaction of CsPbBr
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Perovskite Nanocrystals: Affinity of Halide Ion Matters. ChemistrySelect 2022. [DOI: 10.1002/slct.202203868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- P. Divya
- Department of Chemistry Government Victoria College Research Center under University of Calicut Palakkad 678001 India
| | - G. Anagha
- Department of Chemistry Government Victoria College Research Center under University of Calicut Palakkad 678001 India
| | - Bijoy Nharangatt
- Department of Physics National Institute of Technology Calicut, Kerala 673601 India
| | - Raghu Chatanathodi
- Department of Physics National Institute of Technology Calicut, Kerala 673601 India
| | - H. Sabrin
- Department of Chemistry Government Victoria College Research Center under University of Calicut Palakkad 678001 India
| | - N. Nourin
- Department of Chemistry Government Victoria College Research Center under University of Calicut Palakkad 678001 India
| | - K. H. Fausia
- Department of Chemistry Government Victoria College Research Center under University of Calicut Palakkad 678001 India
| | - K. Padmakumar
- Department of Chemistry Government Victoria College Research Center under University of Calicut Palakkad 678001 India
| | - Deepthi Jose
- Department of Chemistry Providence Women's College Calicut 673009 India
| | - K. Sandeep
- Department of Chemistry Government Victoria College Research Center under University of Calicut Palakkad 678001 India
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Roy D, De CK, Ghosh S, Mukherjee S, Mandal S, Mandal PK. Ultrafast dynamics and ultrasensitive single particle spectroscopy of optically robust core/alloy shell semiconductor quantum dots. Phys Chem Chem Phys 2022; 24:8578-8590. [PMID: 35355030 DOI: 10.1039/d1cp05780d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A "one-pot one-step" synthesis method of Core/Alloy Shell (CAS) quantum dots (QDs) offers the scope of large scale synthesis in a less time consuming, more economical, highly reproducible and high-throughput manner in comparison to "multi-pot multi-step" synthesis for Core/Shell (CS) QDs. Rapid initial nucleation, and smooth & uniform shell growth lead to the formation of a compositionally-gradient alloyed hetero-structure with very significantly reduced interfacial trap density in CAS QDs. Thus, interfacial strain gets reduced in a much smoother manner leading to enhanced confinement for the photo-generated charge carriers in CAS QDs. Convincing proof of alloy-shelling for a CAS QD has been provided from HRTEM images at the single particle level. The band gap could be tuned as a function of composition, temperature, reactivity difference of precursors, etc. and a high PLQY and improved photochemical stability could be achieved for a small sized CAS QD. From the ultrafast exciton dynamics in CdSe and InP CAS QDs, it has been shown that (a) the hot exciton thermalization/relaxation happens in <500 fs, (b) hot electron trapping dynamics occurs within a ∼1 ps time scale, (c) band edge exciton trapping occurs within a 10-25 ps timescale and (d) for CdSe CAS QDs the hot hole gets trapped in about 35 ps. From fast PL decay dynamics, it has been shown that the amplitude of the intermediate time constant can be correlated with the PLQY. A model has been provided to understand these ultrafast to fast exciton dynamical processes. At the ultrasensitive single particle level, unlike CS QDs, CdSe CAS QDs have been shown to exhibit (a) constancy of PLmax (i.e. no bluing) and (b) constancy of PL intensity (i.e. no bleaching) of the single CAS QDs for continuous irradiation for one hour under an air atmosphere. Thus, CAS QDs hold the promise of being a superior optical probe in comparison to CS QDs both at the ensemble and at the single particle level, leading to enhanced flexibility of the CAS QDs towards designing and developing next generation application devices.
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Affiliation(s)
- Debjit Roy
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India.
| | - Chayan K De
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India.
| | - Swarnali Ghosh
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India.
| | - Soumen Mukherjee
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India.
| | - Saptarshi Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India.
| | - Prasun K Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India. .,Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
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Roy D, Ghosh S, De CK, Mukherjee S, Mandal S, Mandal PK. Excitation-Energy-Dependent Photoluminescence Quantum Yield is Inherent to Optically Robust Core/Alloy-Shell Quantum Dots in a Vast Energy Landscape. J Phys Chem Lett 2022; 13:2404-2417. [PMID: 35257586 DOI: 10.1021/acs.jpclett.2c00157] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The importance of alloy-shelling in optically robust Core/Alloy-Shell (CAS) QDs has been described from structural and energetic aspects. Unlike fluorescent dyes, both Core/Shell (CS) and CAS QDs exhibit excitation-energy-dependent photoluminescence quantum yield (PLQY). For both CdSe and InP CAS QDs (with metal- and nonmetal-based alloy-shelling, respectively), with increasing excitation energy, (a) the ultrafast rise-time or relaxation-time to the band-edge increases and (b) the magnitude of the normalized bleach signal decreases. Ultrasensitive single-particle spectroscopic investigation results showed that with decreasing excitation energy, (a) the fraction of ON events increases, (b) the ratio of exciton-detrapping rate/trapping rate increases, and (c) the extent of beneficial hole trapping increases. A relative decrease in PLQY with increasing excitation energy is much less pronounced in CAS QDs than in CS QDs. Unless trap states are removed completely especially in the higher-energy landscape, PLQY will remain inherently dependent on excitation energy for QDs in the vast energy landscape. When reporting the PLQY of QDs, the magnitude of the excitation energy must be mentioned.
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Affiliation(s)
- Debjit Roy
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Swarnali Ghosh
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Chayan K De
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Soumen Mukherjee
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Saptarshi Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Prasun K Mandal
- Department of Chemical Sciences & Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
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Mandal S, Ghosh S, Mukherjee S, Roy D, De CK, Mukhuti K, Mandal PK. Near-Ergodic CsPbBr 3 Perovskite Nanocrystal with Minimal Statistical Aging. J Phys Chem Lett 2021; 12:10169-10174. [PMID: 34643402 DOI: 10.1021/acs.jpclett.1c02326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Optical robustness, uniformity, ergodicity, statistical aging, etc. dictate the applicability of nanocrystals. Based on a series of multimodal statistical analyses such as the Kolmogorov-Smirnov test, Lévy statistics, etc., we demonstrate that for CsPbBr3 perovskite nanocrystals (PNCs): (a) the extent of heterogeneity in the quality and associated physical processes is minimal; (b) the optical robustness is very high, and (c) indeed, a single PNC can depict optical behavior of its ensemble. In addition, toward prospective applications, an optically robust CsPbBr3 PNC exhibits (i) near-ergodicity and (ii) minimal statistical aging, which are extremely vital and complementary to its high defect tolerance.
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Affiliation(s)
- Saptarshi Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Swarnali Ghosh
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Soumen Mukherjee
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Debjit Roy
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Chayan K De
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Kingshuk Mukhuti
- Department of Physical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
| | - Prasun K Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
- Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, India 741246
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Mulder J, du Fossé I, Alimoradi Jazi M, Manna L, Houtepen AJ. Electrochemical p-Doping of CsPbBr 3 Perovskite Nanocrystals. ACS ENERGY LETTERS 2021; 6:2519-2525. [PMID: 34307881 PMCID: PMC8294022 DOI: 10.1021/acsenergylett.1c00970] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 06/15/2021] [Indexed: 05/21/2023]
Abstract
Lead halide perovskite nanocrystals have drawn attention as active light-absorbing or -emitting materials for opto-electronic applications due to their facile synthesis, intrinsic defect tolerance, and color-pure emission ranging over the entire visible spectrum. To optimize their application in, e.g., solar cells and light-emitting diodes, it is desirable to gain control over electronic doping of these materials. However, predominantly due to the intrinsic instability of perovskites, successful electronic doping has remained elusive. Using spectro-electrochemistry and electrochemical transistor measurements, we demonstrate here that CsPbBr3 nanocrystals can be successfully and reversibly p-doped via electrochemical hole injection. From an applied potential of ∼0.9 V vs NHE, the emission quenches, the band edge absorbance bleaches, and the electronic conductivity quickly increases, demonstrating the successful injection of holes into the valence band of the CsPbBr3 nanocrystals.
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Affiliation(s)
- Jence
T. Mulder
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, The Netherlands
| | - Indy du Fossé
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, The Netherlands
| | - Maryam Alimoradi Jazi
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, The Netherlands
| | - Liberato Manna
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, The Netherlands
- Department
of Nanochemistry, Istituto Italiano di Tecnologia
(IIT), Via Morego 30, 16163 Genova, Italy
| | - Arjan J. Houtepen
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, The Netherlands
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Ghosh S, Mandal S, Mukherjee S, De CK, Samanta T, Mandal M, Roy D, Mandal PK. Near-Unity Photoluminescence Quantum Yield and Highly Suppressed Blinking in a Toxic-Metal-Free Quantum Dot. J Phys Chem Lett 2021; 12:1426-1431. [PMID: 33522828 DOI: 10.1021/acs.jpclett.0c03519] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
There is no literature report of simultaneously achieving near-unity PLQY (ensemble level) and highly suppressed blinking (ultrasensitive single-particle spectroscopy (SPS) level) in a toxic-metal-free QD. In this Letter we report accomplishing near-unity PLQY (96%) and highly suppressed blinking (>80% ON fraction) in a toxic-metal-free CuInS2/ZnSeS Core/Alloy-Shell (CAS) QD. In addition, (i) gigantic enhancement of PLQY (from 15% (Core) to 96% (CAS QD)), (ii) ultrahigh stability over 1 year without significant reduction of PLQY at the ensemble level, (iii) high magnitude (nearly 3 times) of electron detrapping/trapping rate, and (iv) very long ON duration (∼2 min) without blinking at the SPS level enable this ultrasmall (∼3.3 nm) CAS QD to be quite suitable for single-particle tracking/bioimaging. A model explaining all these excellent optical properties has been provided. This ultrabright CAS QD has been successfully utilized toward fabrication of low-cost microcontroller-based stable and bright yellow and white QD-LEDs.
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