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Mn-Doped Semiconductor Nanocrystals: 25 Years and Beyond
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host,1 gradually this was extended to other binary,4 ternary, alloyed,22 and also to complex nanostructures.23 Other leading findings include the size-dependent evolution of Mn d−d emission from CdSe,8 efficient doping in alloy nanocrystals,22 thermal stability in doped ZnSe,24 temperature-dependent emission switching in doped complex type core−shell structures,6 doping in CuInS2−ZnS and AgInS2−ZnS multinary systems,25 etc. In addition, by tuning the synthetic strategies and using different spectroscopic techniques, the origin of the exciton-dopant−state energy transfer leading to the spin inverted d−d emission was extensively studied. Furthermore, the doped nanocrystals were also explored for water dispersion,26 bioimaging,27 photovoltaics,28 solar concentrators,29 fluorescence resonance energy transfer,30 and solar water splitting.31 Although, theoretically, it was established that the emission is nontunable; but, by tuning the ligand field energy, the emission could also be tuned beyond the 50 nm spectral window.32 It is indeed difficult to summarize the entire developments reported by thousands of research papers, but some of the important findings of several leading research group leaders are summarized as follows: Bhargava (1994): Predominate Mn d−d emission from Mn-doped ZnS nanocrystals.1 Bawendi (2000): Mn dopants in surface doping in wurtzite phase CdSe can be washed out.3 Norris (2001): High-quality Mn d−d emission from Mndoped ZnS by following high-temperature organometallic synthesis approach.4 Erwin (2005): Doping Mn(II) is a surface adsorption phenomenon.33 Peng (2005): Doping with pure dopant emission in ZnSe can be possible; reported the exclusive Mn d−d emission measured at room temperature.34 Cao (2006): Radial position−dependent efficient exciton energy transfer from host to dopant states.35 Gamelin (2010): Obtaining Mn d−d emission from CdSe: size of the host matters.6 Sarma (2008): Alloys can give better room for dopants. The group studied Mn-doping in CdZnS.22 Kamat (2012): Mn doping in semiconductor can result in better solar cell efficiency.28 Meijerink (2012): Doping Mn in magic-size ZnTe clusters.36 Dong (2015): Hot electrons from doped nanocrystals can exhibit enhanced photocatalytic activity in H2 production reaction.31 Hyeon (2015): Smallest doped nanocrystals synthesized for CdSe host.37 Klimov (2017): Doping Mn in CsPbCl3 can result in efficient Mn d−d emission.10
oping Mn(II) in high bandgap semiconductor hosts is widely known for its yellow-orange emission, typically centered within 580−600 nm. The unique feature of this emission that identifies its origin from Mn(II) is its longer excited-state decay lifetime. As an optically active dopant in nanocrystalline materials, it has been studied for 25 years and achieved several milestones. The doping was first performed with different chalcogenide materials, and it has also been extended to recently emerged perovskite nanocrystals. Analyzing the entire journey of this Mn(II) dopant in different nanocrystal hosts, this Viewpoint provides several achievements obtained, from fundamentals to applied research, and also quotes important findings of some of the leading researchers. From literature reports, it is revealed that the first milestone in focusing the intensive research on Mn(II) doping was the Mn-doped ZnS nanocrystals reported by Bhargava and coworkers1 in 1994. This work presents for the first time the intense Mn d−d emission achieved from the host excitation. By this time, in 1993, Bawendi and co-workers2 had already reported the high-temperature organometallic synthesis route for obtaining high-quality CdSe nanocrystals. Hence, this method was further adopted for continuing the doping in different nanocrystal hosts. Unfortunately, solid evidence of Mn being retained in the wurtzite−CdSe phase could not be established.3 However, in 2001, following this organometallic route for the high-temperature colloidal synthesis, the Norris group successfully achieved doping in ZnSe and discussed the location of Mn(II) ions.4 Then, this became an emerging field, and intensive research had been carried out on understanding the concept of doping, the physical insights of doping, phaseselective doping, diffusion doping, and understanding the optical properties of the doped nanocrystals.5−9 Recently, this was also extended to perovskites and layered perovskite nanostructures.10−18 Schematic presentations of the placement of Mn(II) in the tetrahedral and octahedral lattices in chalcogenides and perovskite nanostructures are shown in Figure 1a,b. Digital images showing the illuminated dispersed solution of different Mn-doped nanocrystals are shown in Figure 2a−e. Figure 3a presents histogram profiles of number of publications versus year of publication obtained from the search words “Mn doped nanocrystals”. From these data, it is revealed that a rise in the number of publications was noticed after the year 2000 and became steady during 2013−2018. This was presumably because of the familiarity of the hightemperature colloidal synthesis approach due to developments of several simplified methods other than use of organometallic compounds. A similar trend is also observed for the search with words “Mn doped,” which included the bulk material and related contents (Figure 3b), and the trend also remained the same. Several reviews on Mn doping were also reported, and the developments from fundamentals to applications have been summarized.20,21 Although the first reports were with a ZnS © 2019 American Chemical Society
Received: April 18, 2019 Accepted: May 3, 2019 Published: May 16, 2019 2574
DOI: 10.1021/acs.jpclett.9b01107 J. Phys. Chem. Lett. 2019, 10, 2574−2577
Viewpoint
The Journal of Physical Chemistry Letters
Figure 1. (a) Atomic model showing Mn-doped ZnS, where orange and blue tetrahedrons indicate Mn and Zn centers, respectively. Single tetrahedrons of undoped and doped lattices are also shown with an arrow. (b) Atomic model showing Mn-doped CsPbCl3 crystal, where blue octahedrons have Pb and orange have Mn in their centers.
Figure 2. Digital images of (a) Mn:ZnS, (b) Mn:ZnSe, (c) Mn: CsPbCl3 (180 °C temperature synthesis), (d) Mn:CsPbCl3 (260 °C temperature synthesis), (e) thiol-treated Mn-doped ZnSe nanocrystals under illumination. Images in panels b, c, and d are reproduced from refs 11, 17, and 19. Copyright American Chemical Society for panel b and d. Copyright Wiley VCH for panel c.
Figure 3. Histograms showing the number of publications versus publication year with the search words (a) “Mn doped nanocrystals” and (b) “Mn doped”. These data were obtained from the Web of Science search database.
have suggested that some properties also differ.40 For example, the trend in the temperature-dependent emission intensities varies from chalcogenides to 3D perovskites and again from 3D to 2D perovskite nanostructures.13 Hence, there is still more rooms for understanding and investigating the fundamentals of the emission properties of these materials. The hosts are typically high-bandgap materials, so the doped nanocrystals have minimum self-absorption; hence, these might be ideal for future applications in solid-state lighting technology. However, developing methodologies for suppressing the interference of defect states, achieving stability in different dispersive mediums, searching for new kinds of hosts for providing
In addition, a large number of young research groups also added significant research contributions on Mn-doping, but because of space constraints, it would be difficult to list them all. Besides the chalcogenide hosts, recent developments on Mn doping in perovskite nanocrystals were also extensively studied. In recent reviews, several achievements on doping in perovskites and also the challenges ahead are summarized.38,39 Although some of the emission properties (position, excitedstate decay lifetime, fwhm, etc.) of the Mn dopant remain unique for all kinds of hosts, such as binary, ternary, or complex nanostructures, either in the nanodimension or bulk, and in chalcogenide or perovskite hosts; but, recent studies 2575
DOI: 10.1021/acs.jpclett.9b01107 J. Phys. Chem. Lett. 2019, 10, 2574−2577
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The Journal of Physical Chemistry Letters
(13) Dutta, S. K.; Dutta, A.; Das Adhikari, S.; Pradhan, N. Doping Mn2+ in single-crystalline layered perovskite microcrystals. ACS Energy Lett. 2019, 4, 343−351. (14) Mir, W. J.; Jagadeeswararao, M.; Das, S.; Nag, A. Colloidal MnDoped Cesium Lead Halide Perovskite Nanoplatelets. ACS Energy Lett. 2017, 2, 537−543. (15) Xu, W.; Li, F.; Lin, F.; Chen, Y.; Cai, Z.; Wang, Y.; Chen, X. Synthesis of CsPbCl3-Mn Nanocrystals via Cation Exchange. Adv. Opt. Mater. 2017, 5, 1700520−1700524. (16) Xu, K.; Lin, C. C.; Xie, X.; Meijerink, A. Efficient and Stable Luminescence from Mn2+ in Core and Core-Isocrystalline Shell CsPbCl3 Perovskite Nanocrystals. Chem. Mater. 2017, 29, 4265− 4272. (17) Das Adhikari, S.; Behera, R. K.; Bera, S.; Pradhan, N. Presence of Metal Chloride for Minimizing the Halide Deficiency and Maximizing the Doping Efficiency in Mn(II)-Doped CsPbCl3 Nanocrystals. J. Phys. Chem. Lett. 2019, 10, 1530−1536. (18) Zhu, J.; Yang, X.; Zhu, Y.; Wang, Y.; Cai, J.; Shen, J.; Sun, L.; Li, C. Room-Temperature Synthesis of Mn-Doped Cesium Lead Halide Quantum Dots with High Mn Substitution Ratio. J. Phys. Chem. Lett. 2017, 8, 4167−4171. (19) Acharya, S.; Sarma, D. D.; Jana, N. R.; Pradhan, N. An Alternate Route to High-Quality ZnSe and Mn-Doped ZnSe Nanocrystals. J. Phys. Chem. Lett. 2010, 1, 485−488. (20) Norris, D. J.; Efros, A. L.; Erwin, S. C. Doped nanocrystals. Science 2008, 319, 1776−1779. (21) Pradhan, N.; Sarma, D. D. Advances in Light-Emitting Doped Semiconductor Nanocrystals. J. Phys. Chem. Lett. 2011, 2, 2818− 2826. (22) Nag, A.; Chakraborty, S.; Sarma, D. D. To Dope Mn2+ in a Semiconducting Nanocrystal. J. Am. Chem. Soc. 2008, 130, 10605− 10611. (23) Shen, S.; Zhang, Y.; Liu, Y.; Peng, L.; Chen, X.; Wang, Q. Manganese-Doped Ag2S-ZnS Heteronanostructures. Chem. Mater. 2012, 24, 2407−2413. (24) Pradhan, N.; Peng, X. Efficient and Color-Tunable Mn-Doped ZnSe Nanocrystal Emitters: Control of Optical Performance via Greener Synthetic Chemistry. J. Am. Chem. Soc. 2007, 129, 3339− 3347. (25) Manna, G.; Jana, S.; Bose, R.; Pradhan, N. Mn-Doped Multinary CIZS and AIZS Nanocrystals. J. Phys. Chem. Lett. 2012, 3, 2528−2534. (26) Pradhan, N.; Battaglia, D. M.; Liu, Y.; Peng, X. Efficient, Stable, Small, and Water-Soluble Doped ZnSe Nanocrystal Emitters as NonCadmium Biomedical Labels. Nano Lett. 2007, 7, 312−317. (27) Thakar, R.; Chen, Y.; Snee, P. T. Efficient Emission from Core/ (Doped) Shell Nanoparticles: Applications for Chemical Sensing. Nano Lett. 2007, 7, 3429−3432. (28) Santra, P. K.; Kamat, P. V. Mn-Doped Quantum Dot Sensitized Solar Cells: A Strategy to Boost Efficiency over 5%. J. Am. Chem. Soc. 2012, 134, 2508−2511. (29) Erickson, C. S.; Bradshaw, L. R.; McDowall, S.; Gilbertson, J. D.; Gamelin, D. R.; Patrick, D. L. Zero-Reabsorption DopedNanocrystal Luminescent Solar Concentrators. ACS Nano 2014, 8, 3461−3467. (30) Sarkar, S.; Bose, R.; Jana, S.; Jana, N. R.; Pradhan, N. Doped Semiconductor Nanocrystals and Organic Dyes: An Efficient and Greener FRET System. J. Phys. Chem. Lett. 2010, 1, 636−640. (31) Dong, Y.; Choi, J.; Jeong, H.-K.; Son, D. H. Hot Electrons Generated from Doped Quantum Dots via Upconversion of Excitons to Hot Charge Carriers for Enhanced Photocatalysis. J. Am. Chem. Soc. 2015, 137, 5549−5554. (32) Pradhan, N. Red-Tuned Mn d−d Emission in Doped Semiconductor Nanocrystals. ChemPhysChem 2016, 17, 1087−1094. (33) Erwin, S. C.; Zu, L.; Haftel, M. I.; Efros, A. L.; Kennedy, T. A.; Norris, D. J. Doping Semiconductor Nanocrystals. Nature 2005, 436, 91−94. (34) Pradhan, N.; Goorskey, D.; Thessing, J.; Peng, X. An Alternative of CdSe Nanocrystal Emitters: Pure and Tunable Impurity
efficient exciton energy transfer, obtaining bulk-scale materials without compromising the quality, and processing these in making different light-emitting devices remain challenges and can be addressed in future research. In summary, a brief history of the development of lightemitting Mn-doped nanocrystals in the last 25 years is reported. Several important findings on the concept of doping and the developed methodology for obtaining doped nanocrystals are discussed. In addition, future prospects for potential doping materials, the challenges ahead for understanding more about doping, and the implementation of doped nanocrystals are also stated briefly.
Narayan Pradhan*
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School of Materials Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. ORCID
Narayan Pradhan: 0000-0003-4646-8488 Notes
The author declares no competing financial interest.
■
REFERENCES
(1) Bhargava, R. N.; Gallagher, D.; Hong, X.; Nurmikko, A. Optical Properties of Manganese-doped Nanocrystals of Zinc Sulfide. Phys. Rev. Lett. 1994, 72, 416−19. (2) Murray, C. B.; Norris, D. J.; Bawendi, M. G. Synthesis and Characterization of Nearly Monodisperse CdE (E = sulfur, selenium, tellurium) Semiconductor Nanocrystallites. J. Am. Chem. Soc. 1993, 115, 8706−15. (3) Mikulec, F. V.; Kuno, M.; Bennati, M.; Hall, D. A.; Griffin, R. G.; Bawendi, M. G. Organometallic Synthesis and Spectroscopic Characterization of Manganese Doped CdSe Nanocrystals. J. Am. Chem. Soc. 2000, 122, 2532−2540. (4) Norris, D. J.; Yao, N.; Charnock, F. T.; Kennedy, T. A. HighQuality Manganese-Doped ZnSe Nanocrystals. Nano Lett. 2001, 1, 3−7. (5) Acharya, S.; Pradhan, N. Insertion/Ejection of Dopant Ions in Composition Tunable Semiconductor Nanocrystals. J. Phys. Chem. C 2011, 115, 19513−19519. (6) Vlaskin, V. A.; Janssen, N.; van Rijssel, J.; Beaulac, R.; Gamelin, D. R. Tunable Dual Emission in Doped Semiconductor Nanocrystals. Nano Lett. 2010, 10, 3670−3674. (7) Beaulac, R.; Archer, P. I.; van Rijssel, J.; Meijerink, A.; Gamelin, D. R. Exciton Storage by Mn2+ in Colloidal Mn2+-Doped CdSe Quantum Dots. Nano Lett. 2008, 8, 2949−2953. (8) Beaulac, R.; Archer, P. I.; Liu, X.; Lee, S.; Salley, G. M.; Dobrowolska, M.; Furdyna, J. K.; Gamelin, D. R. Spin-Polarizable Excitonic Luminescence in Colloidal Mn2+-Doped CdSe Quantum Dots. Nano Lett. 2008, 8, 1197−1201. (9) Rossi, D.; Parobek, D.; Dong, Y.; Son, D. H. Dynamics of Exciton-Mn Energy Transfer in Mn-Doped CsPbCl3 Perovskite Nanocrystals. J. Phys. Chem. C 2017, 121, 17143−17149. (10) Liu, W.; Lin, Q.; Li, H.; Wu, K.; Robel, I.; Pietryga, J. M.; Klimov, V. I. Mn2+-Doped Lead Halide Perovskite Nanocrystals with Dual-Color Emission Controlled by Halide Content. J. Am. Chem. Soc. 2016, 138, 14954−14961. (11) Das Adhikari, S.; Dutta, S. K.; Dutta, A.; Guria, A. K.; Pradhan, N. Chemically Tailoring the Dopant Emission in Manganese-Doped CsPbCl3 Perovskite Nanocrystals. Angew. Chem., Int. Ed. 2017, 56, 8746−8750. (12) Das Adhikari, S.; Dutta, A.; Dutta, S. K.; Pradhan, N. Layered Perovskites L2(Pb1‑xMnx)Cl4 to Mn-Doped CsPbCl3 Perovskite Platelets. ACS Energy Lett. 2018, 3, 1247−1253. 2576
DOI: 10.1021/acs.jpclett.9b01107 J. Phys. Chem. Lett. 2019, 10, 2574−2577
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The Journal of Physical Chemistry Letters Emissions in ZnSe Nanocrystals. J. Am. Chem. Soc. 2005, 127, 17586− 17587. (35) Yang, Y.; Chen, O.; Angerhofer, A.; Cao, Y. C. Radial-PositionControlled Doping in CdS/ZnS Core/Shell Nanocrystals. J. Am. Chem. Soc. 2006, 128, 12428−12429. (36) Eilers, J.; Groeneveld, E.; de Mello Donegá, C.; Meijerink, A. Optical Properties of Mn-Doped ZnTe Magic Size Nanocrystals. J. Phys. Chem. Lett. 2012, 3, 1663−1667. (37) Yang, J.; Fainblat, R.; Kwon, S. G.; Muckel, F.; Yu, J. H.; Terlinden, H.; Kim, B. H.; Iavarone, D.; Choi, M. K.; Kim, I. Y.; et al. Route to the Smallest Doped Semiconductor: Mn2+-Doped (CdSe)13 Clusters. J. Am. Chem. Soc. 2015, 137, 12776−12779. (38) Guria, A. K.; Dutta, S. K.; Das Adhikari, S.; Pradhan, N. Doping Mn2+ in Lead Halide Perovskite Nanocrystals: Successes and Challenges. ACS Energy Lett. 2017, 2, 1014−1021. (39) Das Adhikari, S.; Guria, A.; Pradhan, N. Insights of Doping and the Photoluminescence Properties of Mn-Doped Perovskite Nanocrystals. J. Phys. Chem. Lett. 2019, 10, 2250−2257. (40) Yuan, X.; Ji, S.; De Siena, M. C.; Fei, L.; Zhao, Z.; Wang, Y.; Li, H.; Zhao, J.; Gamelin, D. R. Photoluminescence Temperature Dependence, Dynamics, and Quantum Efficiencies in Mn2+-Doped CsPbCl3 Perovskite Nanocrystals with Varied Dopant Concentration. Chem. Mater. 2017, 29, 8003−8011.
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