![]() ![]() These results lay the foundation for rational design of QD-LED structure and offer a practicable platform for the realization of transparent QD-based displays and lightings.įigure 1a shows the representative TEM image of the CdSe/CdS/ZnS QDs. Our work offers a simple, reliable and cost-effective approach to fabricate transparent QD-LEDs. The maximum luminance (efficiency) for ITO and AgNWs side is 25,040 cd/m 2 (5.6 cd/A) and 23,440 cd/m 2 (5.2 cd/A), respectively. The device performances, including luminance, efficiency and electroluminescence (EL) spectra, are nearly identical for both sides of the transparent QD-LEDs. The charge carriers are injected into the QD-LEDs through an ITO anode and an AgNW cathode. In this study, we fabricated transparent QD-LEDs through all-solution techniques and not any vacuum processes were involved. ![]() We can anticipate that AgNW film should be a suitable alternative electrode in vacuum-free QD-LEDs. It has been reported that AgNW film with highly average transmittance of 85% and low Rs of 10 Ω sq −1can be achieved using a simple drop casting technique 27. AgNW film are fairly stable and can be prepared with excellent control regarding wire geometry, including nanowire length and diameter 26. Recently, an electronic material, a random silver nanowire (AgNW) network film, has been explored for photoelectric applications 21, 22, 23, 24, 25 where low sheet resistance (Rs) and high optical transparency (T) in the visible and infrared spectral range are required. However, the cathode is still deposited via thermal evaporation in a high-vacuum chamber. At present, the organic/inorganic functional layers used in QD-LEDs, such as poly(N,N’-bis(4-butylphenyl)-N,N’-bis(phenyl)benzidine) (poly-TPD) 7, Poly (TFB) 17, 18, Poly(9-vinylcarbazole) (PVK) 16, 19, ZnO nanopartilces 13 and sol-gel TiO 2 20, can be obtained by a low-cost solution process. In order to meet the commercialization requirement, the manufacturing cost of the QD-LEDs must be dramatically decreased. The high vacuum techniques are expensive and complicated, which increases the cost in mass production and limits the commercialization process of organic LEDs and QD-LEDs. ![]() As common organic LEDs, the vacuum thermal evaporation is often required to obtain organic active layer and metal electrode in QD-LEDs fabrication processes. However, there are still some critical roadblocks, as achieving commercial success will likely require the exploitation of key strengths, such as non-vacuum roll-to-roll type manufacturing and opportunities in flexible applications. Recently, some record performance parameters for QD-LEDs, such as maximum luminance over 200,000 cd/m 2 and high external quantum efficiency of approximately 20.5%, have been reported with an organic/inorganic hybrid device structure 13, 16. ![]() Since the first report on the QD-LEDs 3, great effort has been devoted to achieving highly efficient QD-LEDs through a variety of means and there has been numerous progress in improving the device performance by optimizing both QD materials and device architectures 13, 14, 15. Further, QD-LEDs exhibit significant advantages over liquid crystal displays and organic LEDs 8, 9, 10, 11, 12, including wide gamut and saturated emission. Therefore, QDs light emitting diodes (QD-LEDs) are being pursued with much anticipation as viable alternatives to GaN based LEDs and organic LEDs, which dominate today’s market. During the last two decades, semiconductor quantum dots (QDs) are much attractive as light-emitting materials owing to their unique potential properties, including tunable emission from UV to near infrared, pure emission color, low-cost solution processes and high efficiency 1, 2, 3, 4, 5, 6, 7, 8. ![]()
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