Mühendislik Fakültesi

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Browsing Mühendislik Fakültesi by Author "0000-0001-5215-9740"

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    Management of electroluminescence from silver-doped colloidal quantum well light-emitting diodes
    (Cell Press, 2022) Liu, Baiquan; Sharma, Manoj; Yu, Junhong; Wang, Lin; Shendre, Sushant; Sharma, Ashma; Izmir, Merve; Delikanli, Savas; Altintas, Yemliha; Dang, Cuong; Sun, Handong; Demir, Hilmi Volkan; 0000-0001-9375-7683; 0000-0001-5215-9740; 0000-0001-6183-4082; 0000-0002-2261-7103; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Altıntaş, Yemliha
    Impurity doping is a promising strategy to afford colloidal nanocrystals exhibiting novel optical, catalytic, and electronic characteristics. However, some significant properties of noble metal-doped nanocrystals (NMD-NCs) remain unknown. Here, we report the electroluminescence (EL) from NMD-NCs. By doping silver impurity into cadmium selenide colloidal quantum wells (CQWs), dual-emission emitters are achieved and a light-emitting diode (LED) with a luminance of 1,339 cd m−2 is reported. In addition, the proposed energy gap engineering to manage exciton recombination is a feasible scheme for tunable EL emissions (e.g., the dopant emission is tuned from 606 to 761 nm). Furthermore, an organic-inorganic hybrid white LED based on CQWs is realized, reaching a color rendering index of 82. Moreover, flexible CQW-LEDs are reported. The findings present a step to unveil the EL property of NMD-NCs, which can be extended to other noble metal impurities, and pave the pathway for NMD-NCs as a class of electronic materials for EL applications.
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    Record High External Quantum Efficiency of 19.2% Achieved in Light-Emitting Diodes of Colloidal Quantum Wells Enabled by Hot-Injection Shell Growth
    (WILEY-V C H VERLAG GMBH, POSTFACH 101161, 69451 WEINHEIM, GERMANY, 2020) Liu, Baiquan; Altintas, Yemliha; Wang, Lin; Shendre, Sushant; Sharma, Manoj; Sun, Handong; Mutlugun, Evren; Demir, Hilmi Volkan; 0000-0003-3715-5594; 0000-0002-2261-7103; 0000-0001-5215-9740; 0000-0003-1793-112X; 0000-0001-9375-7683; AGÜ, Mühendislik Fakültesi, Elektrik - Elektronik Mühendisliği Bölümü
    Colloidal quantum wells (CQWs) are regarded as a highly promising class of optoelectronic materials, thanks to their unique excitonic characteristics of high extinction coefficients and ultranarrow emission bandwidths. Although the exploration of CQWs in light-emitting diodes (LEDs) is impressive, the performance of CQW-LEDs lags far behind other types of soft-material LEDs (e.g., organic LEDs, colloidal-quantum-dot LEDs, and perovskite LEDs). Herein, high-efficiency CQW-LEDs reaching close to the theoretical limit are reported. A key factor for this high performance is the exploitation of hot-injection shell (HIS) growth of CQWs, which enables a near-unity photoluminescence quantum yield (PLQY), reduces nonradiative channels, ensures smooth films, and enhances the stability. Remarkably, the PLQY remains 95% in solution and 87% in film despite rigorous cleaning. Through systematically understanding their shape-, composition-, and device-engineering, the CQW-LEDs using CdSe/Cd0.25Zn0.75S core/HIS CQWs exhibit a maximum external quantum efficiency of 19.2%. Additionally, a high luminance of 23 490 cd m(-2), extremely saturated red color with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.715, 0.283), and stable emission are obtained. The findings indicate that HIS-grown CQWs enable high-performance solution-processed LEDs, which may pave the path for future CQW-based display and lighting technologies.