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Yasufumi Fujiwara
Researcher at Osaka University
Publications - 270
Citations - 3038
Yasufumi Fujiwara is an academic researcher from Osaka University. The author has contributed to research in topics: Photoluminescence & Luminescence. The author has an hindex of 26, co-authored 266 publications receiving 2737 citations. Previous affiliations of Yasufumi Fujiwara include Hokkaido University & Nagoya University.
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Room-Temperature Red Emission from a p-Type/Europium-Doped/n-Type Gallium Nitride Light-Emitting Diode under Current Injection
TL;DR: In this article, the first lowvoltage operation of current-injected red emission from a p-type/Eu-doped/n-type GaN light-emitting diode (LED) at room temperature was demonstrated with an applied voltage as low as 3 V under normal lighting conditions.
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Efficient carrier multiplication in CsPbI3 perovskite nanocrystals.
Chris de Weerd,Leyre Gomez,Antonio Capretti,Delphine Lebrun,Eiichi Matsubara,Eiichi Matsubara,Junhao Lin,Masaaki Ashida,Frank C. M. Spoor,Laurens D. A. Siebbeles,Arjan J. Houtepen,Kazutomo Suenaga,Yasufumi Fujiwara,Tom Gregorkiewicz,Tom Gregorkiewicz +14 more
TL;DR: It is demonstrated that carrier multiplication commences at the threshold excitation energy near the energy conservation limit of twice the band gap, and has step-like characteristics with an extremely high quantum yield of up to 98%.
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Perspective: Toward efficient GaN-based red light emitting diodes using europium doping
Brandon Mitchell,Brandon Mitchell,Brandon Mitchell,Volkmar Dierolf,Tom Gregorkiewicz,Tom Gregorkiewicz,Yasufumi Fujiwara +6 more
TL;DR: In this article, the challenges of attaining red luminescence from GaN under current injection and the methods that have been developed to circumvent them are addressed and a large emphasis is placed on the recent developments of doping GaN with Eu3+ to achieve an efficient red GaN-based LED.
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Direct Observation of Band Structure Modifications in Nanocrystals of CsPbBr3 Perovskite
Junhao Lin,Leyre Gomez,Chris de Weerd,Yasufumi Fujiwara,Tom Gregorkiewicz,Tom Gregorkiewicz,Kazutomo Suenaga +6 more
TL;DR: This work establishes an intimate relation between quantum dot size and even shape and its bandgap energy on a single object level and shows the presence of an effective coupling between proximal dots in an ensemble, leading to band structure modification.
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Improved luminescence properties of Eu-doped GaN light-emitting diodes grown by atmospheric-pressure organometallic vapor phase epitaxy
TL;DR: In this paper, the luminescence properties of Eu-doped GaN (GaN:Eu) grown by atmospheric-pressure organometallic vapor phase epitaxy were investigated.