Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - WoS: 52Citation - Scopus: 52Multiplexed Patterning of Cesium Lead Halide Perovskite Nanocrystals by Additive Jet Printing for Efficient White Light Generation(Elsevier Science SA, 2020-01) Altintas, Yemliha; Torun, Ilker; Yazici, Ahmet Faruk; Beskazak, Emre; Erdem, Talha; Onses, M. Serdar; Mutlugun, Evren; Serdar Onses, M.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.Article Citation - WoS: 12Citation - Scopus: 13Highly Luminescent ZnCdTeS Nanocrystals With Wide Spectral Tunability for Efficient Color-Conversion White-Light(IOP Publishing Ltd, 2021-09-28) Soheyli, Ehsan; Zargoush, Sirous; Yazici, Ahmet Faruk; Sahraei, Reza; Mutlugun, EvrenCdTe-based semiconductor nanocrystals (NCs) with size and composition-dependent efficient bandgap properties are historically mature nanomaterials for colloidal optoelectronic applications. In this work, we present the highly luminescent quaternary ZnCdTeS NCs with tunable emission across a wide visible spectrum from green to red spectral range. Prepared via a direct aqueous-based approach, a second capping agent of trisodium citrate (TSC) was used to enhance the photoluminescence (PL) emission efficiency, the chemical stability, and to spectrally widen the coverage of the emission spectra of ZnCdTeS NCs. Adding TCS created a remarkable blue shift from 572 nm in the absence of TSC, to 548 nm. On the other hand, upon optimization of experimental parameters, superior ZnCdTeS NCs with a narrow PL profile typically less than 50 nm, the high quantum efficiency of 76%, and tunable emission from 515-to-645 nm were synthesized in an aqueous solvent. The keynotes were the superior and reproducible luminescent properties for the core only NCs, without shell and using relatively low reaction temperatures. It was shown that in the suggested synthesis method, the high efficiency emitted color of ZnCdTeS NCs can be easily controlled from 515-to-650 nm with excellent stability against harsh conditions. The biexponential decay profiles of samples prepared at different reaction temperatures demonstrated that the average recombination lifetime is below 40 ns and increases with the growth of the ZnCdTeS NCs. Results reveal that the excitonic energy levels have the main role in the recombination process. Finally, to demonstrate the functional advantages of the prepared NCs in optoelectronics, the NCs were used to fabricate color-conversion white light-emitting diodes. The color coordinate of the device is recorded as (0.4951, 0.3647) with CRI of 91, CCT of 1954 K, and LER of 251 lm W-1 by employing only two distinct emitters for color conversion.