Eight-segment LED displays were designed and fabricated using quantum dot light-emitting diodes. CdSe/CdS/ZnS core/shell quantum dot were employed as the emitting layer sandwiched by poly(N,N -bis(4-butylphenyl)-N,N -bis(phenyl)benzidine) (Poly-TPD) and an electron transport layer of ZnO nanoparticles. Each segment exhibited luminance, power efficiency and external quantum efficiency of 5380 cd/cm 2 , 2.63 lm/W and 1.2%, respectively. The uniformity of the eight segments was analyzed based on the current-density and luminance versus driving voltage. The good uniformity indicates that the as-designed device is useful and promising for general electroluminescent display applications.Semiconductor quantum dots (QDs) have great potentials as a unique optical material because of their inherent luminescent properties, including narrow spectral emission bandwidths, high photoluminescence quantum yield, good photostability, tunable emission wavelength that covers the entire visible region and extends to the infrared region. 1-6 Many potential applications exploiting the advantages of QDs have been suggested, such as optically or electrically pumped lasers, 7 sensors, 8,9 printable thin-film transistors (TFTs), 10 light-emitting diodes (LEDs), 11-13 and photovoltaics. 14,15 In the past decade, quite a few research groups have demonstrated various LEDs using colloidal QDs as the active emitting layers. [16][17][18][19][20] There have been rapid advances in the specifications of luminance, efficiency, and lifetime of QD-LEDs, 16,17 which are even comparable to the well-developed organic light-emitting devices (OLEDs). The QD displays have a more accurate color representation than OLED displays, 18,21 so QDs are potential to simultaneously improve the material stability, lifetime, efficiency, and color purity of OLEDs, while allowing solution-processing techniques in large-area manufacturing. 22 Frontier Research Lab made a display image of a 4-inch cross-linked QD-LED using an a-Si TFT backplane with a 320×240 pixel array for the active matrix drive. 17 Samsung Electronics Advanced Institute of Technology demonstrated full color QD display using a method of transfer printing which had a good quality of brightness and efficiency. 20,23 In this work, we fabricated bright, efficient eight-segment QD-LED displays using CdSe/CdS/ZnS QDs with a simple drive circuit. The QD-LED exhibited a high luminance and a good quality of uniformity.
ExperimentalChemicals.-Cadmium oxide (CdO, 99.998%), selenium (Se, 99.999%), 1-octadecene (ODE, 90%), oleic acid (OA, 90%), sodium hydroxide (NaOH, 98%), zinc acetate (Zn(CH 3 COO) 2, 99.98%) and octadecylamine (ODA, 98%) were purchased from Alfa Aesar. Trioctylphosphine oxide (TOPO, 90%), hexadecylamine (HDA, 90%) and trioctylphosphorus (TOP, 97%) were purchased from SigmaAldrich. Zinc oxide (ZnO, 99.99%) and sulfur (S, 99.99%) were purchased from Aladdin. All organic solvents were purchased from Sigma-Aldrich. The chemicals were used directly without further treatment.z Synthesis of CdSe Core ...