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Publications (International)

Papers

(The University of Electro-Communications)

  1. B. Sk, S. Hirata*, Symmetry-breaking triplet excited state enhances red afterglow enabling ubiquitous afterglow readout, Adv. Sci. 2024, 11, 2308897.
  2. K. Hayashi, S. Hirata*, High-resolution afterglow patterning using cooperative vapo- and photo-stimulation, Small 2024, 20, 2308103.
  3. E. H. Badriyah, K. Hayashi, B. Sk, R. Takano, T. Ishida, S. Hirata*, Continuous condensed triplet accumulation for irradiance-induced anticounterfeit afterglow,  Adv. Sci. 2023, 10, 2304374.
  4. K. Hayashi, K. Fukumoto, S. Hirata*, Photoinduced triplet depletion allowing higher-resolution afterglow, ACS Mater. Lett. 2023, 5, 1649-1655.    
  5. S. Hirata*, T. Kamatsuki, Role of carbonyl distortions facilitating persistent room-temperature phosphorescence, J. Phys. Chem. C 2023, 127, 3861-3871. Invited Article.   
  6. B. Sk, R. Tsuru, K. Hayashi, S. Hirata*, Selective triplet-singlet Förster-resonance energy transfer for bright red afterglow emission, Adv. Funct. Mater. 2023, 11, 2211604. Inside Front Cover Picture.   
  7. S. Hirata*, S. Reineke*, A. Patra*, W. Z. Yuan*, Metal-free room-temperature phosphorescence, Front. Chem. 2022, 10, 1025674. Editorial.
  8. K. Fukasawa, Y. Sugawara, R. Tsuru, T. Yamashita, S. Hirata*, Enhanced red persistent room-temperature phosphorescence induced by orthogonal structure disruption during electronic relaxation, J. Phys. Chem. Lett. 2022, 13, 7788-7796. Invited Article.   
  9. K. Hayashi, K. Fukasawa, T. Yamashita, S. Hirata*, A rational design of triplet afterglow sensitizer allowing bright long-wavelength afterglow room-temperature emission, Chem. Mater. 2022,34, 1627-1637. Supplementary Cover. 
  10. T. Kusama, S. Hirata*, Thermo-reversible persistent phosphorescence modulation reveals the large contribution made by rigidity to the suppression of endothermic intermolecular triplet quenching, Front. Chem. 2021, 7, 788577.  
  11. I. Bhattacharjee, K. Hayashi, S. Hirata*, Key of suppressed triplet nonradiative transition-dependent chemical backbone for spatial self-tunable afterglow, JACS Au 2021, 1, 945-954. Front Cover Picture. 
  12. K. Hayashi, A. Matsumoto, S. Hirata*, Chiral approach to investigate mechanism of highly efficient thermally activated delayed fluorescence, Chem. Commun. 2021, 57, 1738-1741. Inside Front Cover Picture. 
  13. S. Hirata*, I. Bhattacharjee, Vibrational radiationless transition from triplet states of chromophores at room temperature, J. Phys. Chem. A 2021, 125, 885-894.  
  14. S. Hirata*, H. Hara, I. Bhattacharjee, Phosphorescence quenching of heavy-atom-free dopant chromophores triggered by thermally activated triplet exciton diffusion of conjugated crystalline host, J. Phys. Chem. C 2020, 124, 25121-25132. 
  15. T. Kamatsuki, I. Bhattacharjee*, S. Hirata*, The substituent-induced symmetry-forbidden electronic transition allows significant optical limiting under weak sky-blue irradiance, J. Phys. Chem. Lett. 2020, 11, 8675-8681. 
  16. I. Bhattacharjee, S. Hirata*, Highly efficient persistent room-temperature phosphorescence from heavy atom-free molecules triggered by hidden long phosphorescent antenna, Adv. Mater. 2020, 32, 2001348. 
  17. D. K. Sharma*, S. Hirata, M. Vacha*, Energy localization vs. charge funneling in aggregates of CsPbBr3 perovskite nanocrystals, J. Luminescence 2020, 222, 117119. 
  18. S. Hirata*, M. Nishio, H. Uchida, T. Usuki, T. Nakae, M. Miyachi, Y. Yamanoi,* H. Nishihara*: Effect of rris(trimethylsilyl)silyl group on the fluorescence and triplet yields of oligothiophenes, J. Phys. Chem. C 2020, 124, 3277-3286. 
  19. D. K. Sharma*, S. Hirata, M. Vacha*, Single-particle electroluminescence of CsPbBr3 perovskite nanocrystals reveals particle-selective recombination and blinking as key efficiency factors, Nat. Commun. 2019, 10, 4499. 
  20. S. Hirata*, Roles of localized electronic structures caused by π degeneracy due to highly symmetric heavy atom‐free conjugated molecular crystals leading to efficient persistent room‐temperature phosphorescence, Adv. Sci. 2019, 6, 1900410. Front Species. 
  21. D. K. Sharma*, S. Hirata, V. Biju, M. Vacha*, Stark effect and environment-induced modulation of emission in single halide perovskite nanocrystals, ACS Nano, 2019, 13, 624-632. 
  22. K. Narushima, Y. Kiyota, T. Mori, S. Hirata*, M. Vacha*, Suppressed triplet exciton diffusion due to small orbital overlap as a key design factor for ultralong‐lived room‐temperature phosphorescence in molecular crystals, Adv. Mater. 2019, 31, 1807268. 
  23. K. Kanosue, S. Hirata, M. Vacha, R. Augulis, R. Ishige, V. Gulbinas*, S. Ando*, A colorless semi-aromatic polyimide derived from a sterically hindered bromine-substituted dianhydride exhibiting dual fluorescent and phosphorescent emission, Mater. Chem. Front. 2019, 3, 39-49.  
  24. T. Kameyama, M. Kishi, C. Miyamae, D. K. Sharma, S. Hirata, T. Yamamoto, T. Uematsu, M. Vacha, S. Kuwabata*, T. Torimoto*, Wavelength-tunable band-edge photoluminescence of nonstoichiometric Ag–In–S nanoparticles via Ga3+ doping, ACS Appl. Mater. & Interfaces 2018, 12, 42844-42855.  
  25. S. Hatazaki, D. K. Sharma, S. Hirata, K. Nose, T. Iyoda, A. Kölsch, H. Lokstein*, M. Vacha*, Identification of short- and long-wavelength emitting chlorophylls in cyanobacterial photosystem I by plasmon-enhanced single-particle spectroscopy at room temperature, J. Phys. Chem. Lett. 2018, 9, 6669-6678.  
  26. T. Uematsu, K. Wajima, D. K. Sharma, S. Hirata, T. Yamamoto, T. Kameyama, M. Vacha*, T. Torimoto*, S. Kuwabata*, Narrow band-edge photoluminescence from AgInS2 semiconductor nanoparticles by the formation of amorphous III–VI semiconductor shells, NPG Asia Mater. 2018, 10, 713-726.
  27. S. Hirata*, J. Phys. Chem. Lett. 2018, 9, 4251-4259.
  28. T. Hori, K. Totani*, S. Hirata, T. Watanabe*, Large refractive index variations induced by accumulating triplet excitons under photoexcitation at low power, Chem. Phys. Lett. 2018, 704, 5-10.
  29. N. Nakamura, D. K. Sharma, S. Hirata, M. Vacha*, Intra-chain aggregates as the origin of green emission in polyfluorene studied on ensemble and single chain level, J. Phys. Chem. C 2018, 122, 8137-8146.
  30. M. Liu, S. Hirata, T. Iyoda, M. Vacha, P. Piotrowiak*, Excited state behavior of single strand and bulk P3HT in contact with an Au nanowire array, J. Phys. Chem. C 2018, 122, 7925-7933.
  31. B. J. Lidster, S. Hirata, S. Matsuda, T. Yamamoto, V. Komanduri, D. R. Kumar, Y. Tezuka, M. Vacha*, M. L. Turner*, Macrocyclic poly(p-phenylenevinylene)s by ring expansion metathesis polymerisation and their characterization by single-molecule spectroscopy, Chem. Sci. 2018, 9, 2934-2941.

(Tokyo Institute of Technology, Prof. Vacha Group)

  1. Ł. Bujak*, K. Narushima, D. K. Sharma, S. Hirata, M. Vacha*, Plasmon enhancement of triplet excitons diffusion revealed by nanoscale imaging of photochemical fluorescence upconversion, J. Phys. Chem. C 2017, 121, 25479-25486.
  2. S. Hirata*, M. Vacha, Large reverse saturable absorption at sunlight power level using the ultralong lifetime of triplet excitons, J. Phys. Chem. Lett. 2017, 8, 3683-3689.
  3. K. Narushima, S. Hirata*, M. Vacha*, Nanoscale triplet exciton diffusion via imaging of up-conversion emission from single hybrid nanoparticles in molecular crystals, Nanoscale 2017, 9, 10653-10661.
  4. D. K. Sharma*, S. Hirata, Ł. Bujak, V. Biju, T. Kameyama, M. Kishi, T. Torimoto, M. Vacha*. Influence of Zn on the photoluminescence of colloidal (AgIn)xZn2(1-x)S2 nanocrystals, Phys. Chem. Chem. Phys. 2017, 19, 3963-3969.
  5. K. Kamada*, Y. Sakagami, T. Mizokuro, Y. Fujiwara, K. Kobayashi*, K. Narushima, S. Hirata, M. Vacha, Efficient triplet-triplet annihilation upconversion in binary crystalline solids fabricated by solution casting and operated in air, Mater. Horiz. 2017, 4, 83-87.
  6. Ł. Bujak*, T. Ishii, D. K. Sharma, S. Hirata, M. Vacha*, Selective turn-on and modulation of resonant energy transfer in single plasmonic hybrid nanostructures, Nanoscale 2017, 9, 1511-1519.
  7. S. Hirata*, M. Vacha, White afterglow room‐temperature emission from an isolated single aromatic unit under ambient condition, Adv. Opt. Mater. 2017, 5, 1600996.
  8. D. K. Sharma*, S. Hirata, Ł. Bujak, V. Biju, T. Kameyama, M. Kishi, T. Torimoto, M. Vacha*, Single-particle spectroscopy of I-III-VI semiconductor nanocrystals: spectral diffusion and suppression of blinking by two-color excitation, Nanoscale 2016, 8, 13687-13694.
  9. S. Hirata*, K. Shizu, Organic Light-Emitting Diodes: High-throughput virtual screening, Nat. Mater. 2016, 15, 1056-1057. News & Views.
  10. S. Hirata*, M. Vacha, Circularly polarized persistent room-temperature phosphorescence from chiral aromatics in air, J. Phys. Chem. Lett. 2016, 7, 1539-1545.
  11. S. Hirata*, M. Vacha, Large transmittance change induced by exciton accumulation under weak continuous photoexcitation, Adv. Opt. Mater. 2016, 4, 297-305.
  12. Y. Katsurada, S. Hirata*, K, Totani, T. Watanabe, M. Vacha, Photoreversible on-off recording of persistent room-temperature phosphorescence, Adv. Opt. Mater. 2015, 3, 1726-1737. Back Cover, Highlighted by Materials Views, Feb. 17, 2016.
  13. T. Fukushima, J. Yamamoto, M. Fukuchi, S. Hirata, H. H. Jung, O. Hirata, Y. Shibano, C. Adachi, H. Kaji*, Material degradation of liquid organic semiconductors analyzed by nuclear magnetic resonance spectroscopy, AIP Advances 2015, 5, 087124.
  14. T. Imagawa, S. Hirata*, K. Totani, T. Watanabe, M. Vacha, Thermally activated delayed fluorescence with circularly polarized luminescence characteristics, Chem. Commun. 2015, 51, 13268-13271. Inside Back Cover.
  15. Y. Tsubomoto, S. Hirata*, K. Totani, M. Vacha, T. Watanabe, Long-lived triplet excitons allowed by intermolecular hydrogen bonding in amorphous matrix, J. Photo. Sci. Tech. 2015, 28, 573-577.
  16. K. Shizu, Y. Sakai, H. Tanaka, S. Hirata, C. Adachi, H. Kaji*, Meta-linking strategy for small singlet-triplet energy gap of thermally activated delayed fluorescence emitters, ITE Trans. on MTA 2015, 3, 108-113.
  17. S. Lee, K. Noda, S. Hirata, M. Vacha*, Position-dependent three-dimensional diffusion in nematic liquid crystal monitored by single-particle fluorescence localization and tracking, J. Phys. Chem. Lett. 2015, 6, 1403-1407.
  18. S. Hirata, K. Sakai, K. Masui, H. Tanaka, S. Y. Lee, H. Nomura, N. Nakamura, M. Yasumatsu, H. Nakanotani, Q. Zhang, K. Shizu, H. Miyazaki, C. Adachi*, Highly efficient blue electroluminescence based on thermally activated delayed fluorescence, Nat. Mater. 2015, 14, 330-336. Highlighted by Chemistry World, Dec. 8, 2014.
  19. S. Hirata*, K. Totani, T. Yamashita, C. Adachi, M. Vacha*, Large reverse saturable absorption under weak continuous incoherent light, Nat. Mater. 2014, 13, 938-946. Highlighted by Nat. Mater., 13, 917-918, 2014 and Noteworthy Chemistry, Oct. 27, 2014.
  20. Y. Honmou, S. Hirata, H. Komiyama, J. Hiyoshi, S. Kawauchi, T. Iyoda, M. Vacha*, Single molecule electroluminescence and photoluminescence of polyfluorene unveils the photophysics behind the green emission band, Nat. Commun. 2014, 5, 4666.
  21. K. Katayama, S. Hirata, M. Vacha*, Circularly polarized luminescence from individual microstructures of conjugated polymer aggregates with solvent-induced chirality, Phys. Chem. Chem. Phys. 2014, 16, 17983-17987.
  22. S. Furumaki, F. Vacha, S. Hirata, M. Vacha*, Bacteriochlorophyll aggregates self-assembled on functionalized gold nanorod cores as mimics of photosynthetic chlorosomal antennae: a single molecule study, ACS Nano 2014, 8, 2716-2182.
  23. S. Hirata*, K. Totani, H. Kaji, T. Watanabe, M. Vacha, Relationship between room temperature phosphorescence and deuteration position in a purely aromatic compound, Chem. Phys. Lett. 2014, 591, 119-125.
  24. 平田修造*, 安達千波矢, 渡辺敏行, 戸谷健朗, 常温大気中で高効率蓄光機能を示す有機材料, 高分子論文集 2013, 70, 623-636.
  25. H. Kobayashi, S. Hirata, M. Vacha*, Mechanical manipulation of photophysical properties of single conjugated polymer nanoparticles, J. Phys. Chem. Lett. 2013, 4, 2591-2596.
  26. S. Hirata*, K. Totani, H. Kaji, M. Vacha, C. Adachi*, Reversible thermal recording media using time-dependent persistent room temperature phosphorescence. Adv. Opt. Mater. 2013, 1, 438-442. Front Cover Picture.
  27. K. Totani*, Y. Okada, S. Hirata*, M. Vacha, T. Watanabe, Thermoresponsive persistent phosphorescent color change using efficient thermally activated reverse energy transfer with a large energy difference, Adv. Opt. Mater. 2013, 1, 283-288. Front Species.
  28. S. Hirata*, K. Totani, T. Yamashita, H. Kaji, S. R. Marder, T. Watanabe*, C. Adachi*, Efficient persistent room temperature phosphorescence in organic amorphous materials under ambient conditions, Adv. Funct. Mater. 2013, 23, 3386-3397.

(Kyushu University, Prof. Adachi Group)

  1. S. Hirata*, T. Tsuji, Y. Kato, C. Adachi*, Reversible coloration enhanced by electrochemical deposition of an ultra-thin zinc layer onto an anodic nanoporous alumina layer, Adv. Funct. Mater. 2012, 22, 4195-4201.
  2. K. Kubota, S. Hirata, Y. Shibano O. Hirata, M. Yahiro, C. Adachi*, Liquid carbazole substituted with a poly(ethylene oxide) group and its application for liquid organic light emitting diodes, Chem. Lett. 2012, 41, 934-936.
  3. Q. Zhang, J. Li, K. Shizu, S. Huang, S. Hirata, H. Miyazaki, C. Adachi*, Design of efficient thermally activated delayed fluorescence materials for pure blue organic light emitting diodes, J. Am. Chem. Soc. 2012, 134, 14706-14709.
  4. C. H. Shim, S. Hirata, J. Oshima, T. Edura, R. Hattori, C. Adachi*, Uniform and refreshable liquid electroluminescent device with a back side reservoir, Appl. Phys. Lett. 2012, 101, 113302.
  5. S. Hirata, H. J. Heo, Y. Shibano, O. Hirata, M. Yahiro, C. Adachi*, Improved device lifetime of organic light emitting diodes with an electrochemically stable-conjugated liquid host in the liquid emitting layer, Jpn. J. Appl. Phys. 2012, 51, 041604.
  6. S. Hirata, K. Kubota, H. H. Jung, O. Hirata, K. Goushi, M. Yahiro, C. Adachi*, Improvement of electroluminescence performance of organic light emitting diodes with a liquid emitting layer by introduction of electrolyte and a hole-blocking layer, Adv. Mater. 2011, 23, 889-893.
  7. M. Kashiwagi, S. Hirata, K. Harada, Y. Zheng, K. Miyazaki*, M. Yahiro, C. Adachi*, Enhanced figure of merit of a porous thin film of bismuth antimony telluride, Appl. Phys. Lett. 2011, 98, 023114.

(Ph. D course in Tokyo University of Agriculture and Technology, Prof. Watanabe Group)

  1. S. Hirata*, M. Vacha, T. Watanabe: Investigation of quenching mechanism in thermoreversible fluorescent recording materials of fluorescence using thermochromic fluorescence resonance energy transfer, Jpn. J. Appl. Phys. 2010, 49, 052501.
  2. S. Hirata, K. S. Lee, T. Watanabe*, Reversible fluorescent on–off recording in a highly transparent polymeric material utilizing fluorescent resonance energy transfer (FRET) induced by heat treatment, Adv. Funct. Mater. 2008, 18, 2869-2879.
  3. S. Hirata, T. Watanabe*, Reversible thermoresponsive recording of fluorescent images (TRF), Adv. Mater. 2006, 18, 2725-2729.

 

Reviews, Accounts, and Future Articles

  1. B. Sk, S. Hirata*, Förster resonance energy transfer involving the triplet state, Chem. Commum. 2023, 59, 6643-6659, 2023 Pioneering Investigator Issue, Invited Future Artice.
  2. S. Hirata*, Molecular physics of persistent room-temperature phosphorescence and long-lived triplet excitons, Appl. Phys. Revs. 2022, 9, 011304, Invited Review Artice (Featured).
  3. S. Hirata*, Ultralong-lived room temperature triplet excitons: Molecularred persistent room temperature phosphorescence and nonlinear optical characteristics with continuous irradiation, J. Mater. Chem. C 2018, 6, 11785-11794, 2018 Emerging Investigator Issue, Invited Review Article.
  4. M. Vacha*, D. K. Sharma, S. Hirata, Single-molecule studies beyond optical imaging: Multi-parameter single-molecule spectroscopy, Journal of Photochemistry and Photobiology C: Photochemistry 2017, 34, 121-136, Invited Review Article.
  5. S. Hirata*, Recent advances in materials with room‐temperature phosphorescence: Photophysics for triplet exciton stabilization, Adv. Opt. Mater. 2017, 5, 1700116, Back Cover Picture, Invited Review Article.
  6. 平田修造*, 分子性室温りん光と三重項の光物理化学, 光化学協会誌, 2016, 47, 2, 84-91. in Japanese.

 

Representative Awards

Student

  1. Kikura Hayashi, Chemical Science Presentation Prize (RSC) in 2023 Annual Meeting on Photochemistry
  2. Kikura Hayashi, Student Presentation Award in The 103rd CSJ Annual Meeting (2023)

Staff

  1. 2023 Pioneering Investigator in Chemical Communications (RSC)
  2. 2023 Early-Career and Emerging Researcher in The Journal of Physical Chemistry (ACS)
  3. 2018 Emerging Investigator in Journal of Materials Chemistry C (RSC)
  4. 17th The Japanese Photochemistry Association Award for Young Scientist
  5. 65th Chemical Society Japan (CSJ) Award for Young Chemists
  6. 29th Young Scholar Lectures of Chemical Society Japan (CSJ)