Browsing by Author "Beskazak, Emre"

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Arrays of multi-color emitting cesium lead halide perovskite nanocrystals and efficient white light generation by tailored anion exchange reactions and electrohydrodynamic jet printing
(Optica Publishing Group (formerly OSA), 2018) Altintas, Yemliha; Torun, Ilker; Yazici, Ahmet Faruk; Beskazak, Emre; Onses, M. Serdar; Mutlugun, Evren; 0000-0003-2747-7856; 0000-0003-3715-5594; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Altintas, Yemliha; Yazici, Ahmet Faruk; Beskazak, Emre; Mutlugun, Evren
We employ highly efficient and narrow band emitter Cesium-lead-halide perovskite nanocrystals, optimized by the anion exchange method, for efficient white light generation by patterning multiple lines of different colors via proposed electrohydrodynamic jet printing.
Color Simulation and Demonstration of Perovskite Nanocrystal Filters for Wide Color Gamut Displays
(Institute of Electrical and Electronics Engineers Inc., 2018) Genc, Sinan; Yazici, Ahmet Faruk; Beskazak, Emre; Uran, Can; Mutlugun, Evren; 0000-0002-6909-723X; 0000-0003-2747-7856; 0000-0003-3715-5594; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü; Genc, Sinan; Yazici, Ahmet Faruk; Beskazak, Emre; Mutlugun, Evren
In this study, we define spectral parameters of perovskite nanocrystals to improve LCD color gamut, replacing color filters (CFs) with perovskite based subpixels. The optimization of the CFs has been enhanced 15.8% (98.43% of Rec.2020) in simulation and 13.8% experimentally, with 97.37% color gamut coverage.
Multiplexed patterning of cesium lead halide perovskite nanocrystals by additive jet printing for efficient white light generation
(ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND, 2020) Altintas, Yemliha; Torun, Ilker; Yazici, Ahmet Faruk; Beskazak, Emre; Erdem, Talha; Onses, M. Serdar; Mutlugun, Evren; 0000-0001-9820-6565; 0000-0003-2747-7856; 0000-0001-6898-7700; 0000-0003-3905-376X; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü
Inorganic perovskite nanocrystals (PNCs) offer the ability to precisely but also flexibly control the peak emission wavelength while also possessing narrow-band emission spectra and high quantum yields. Owing to these features, PNCs have been already employed as color converters on LEDs. Nevertheless, the anion exchange reactions that prevent the blending of perovskites of different colors remain as an important bottleneck. As a remedy to this issue, here we employ additive jet printing to form separated stripes of these nanocrystals. Within this framework, we first present the synthesis of CsPbBr3 and CsPbBrxI3-x nanocrystals spanning the whole visible regime and optimize the cleaning procedure to obtain PNCs possessing photoluminescence quantum yields as high as 91% and emission linewidths as narrow as 15 nm, making them suitable for high quality white light generation. Next, we employ electrohydrodynamic jet printing to form closely spaced stripes of PNCs of various colors and integrated these films with a blue LED to create a white LED. Our proof-of-concept LED achieves high photometric performance as it possesses a color rendering index of 91.3, luminous efficacy of optical radiation > 300 lm/W-opt, and correlated color temperature of ca. 7000 K. We believe that additive jet printing technique will pave the way for a ubiquitous use of these PNCs in light-emitting devices in the near future.
Plasmon Enhanced Emission of Perovskite Quantum Dot Films
(CAMBRIDGE UNIV PRESS, 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA, 2018) Dadi, Seyma; Altintas, Yemliha; Beskazak, Emre; Mutlugun, Evren; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü
We propose and demonstrate the photoluminescence enhancement of CsPbBr3 perovskite quantum dot films in the presence of Au nanoparticles. Embedded into a polymer matrix, Au nanoparticle-quantum dot film assemble prepared by an easy spin coating method enabled the photoluminescence enhancement of perovskite quantum dot films up to 78%. The properties of the synthesized perovskite QDs and gold nanoparticles have been analysed using high resolution transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, UV-Vis absorption spectrophotometer, steady state and time-resolved photoluminescence spectrometer.