RESUMEN
Narrowing the emission peak width and adjusting the peak position play a key role in the chromaticity and color accuracy of display devices with the use of quantum dot light-emitting diodes (QD-LEDs). In this study, we developed multinary Cu-In-Ga-S (CIGS) QDs showing a narrow photoluminescence (PL) peak by controlling the Cu fraction, i.e., Cu/(In+Ga), and the ratio of In to Ga composing the QDs. The energy gap of CIGS QDs was enlarged from 1.74 to 2.77 eV with a decrease in the In/(In+Ga) ratio from 1.0 to 0. The PL intensity was remarkably dependent on the Cu fraction, and the PL peak width was dependent on the In/(In+Ga) ratio. The sharpest PL peak at 668 nm with a full width at half maximum (fwhm) of 0.23 eV was obtained for CIGS QDs prepared with ratios of Cu/(In+Ga) = 0.3 and In/(In+Ga) = 0.7, being much narrower than those previously reported with CIGS QDs, fwhm of >0.4 eV. The PL quantum yield of CIGS QDs, 8.3%, was increased to 27% and 46% without a PL peak broadening by surface coating with GaSx and Ga-Zn-S shells, respectively. Considering a large Stokes shift of >0.5 eV and the predominant PL decay component of â¼200-400 ns, the narrow PL peak was assignable to the emission from intragap states. QD-LEDs fabricated with CIGS QDs surface-coated with GaSx shells showed a red color with a narrow emission peak at 688 nm with a fwhm of 0.24 eV.
RESUMEN
I-III-VI-based semiconductor quantum dots (QDs) have been intensively explored because of their unique controllable optoelectronic properties. Here we report one-pot synthesis of Na-doped Ag-In-Ga-S (AIGS) QDs incorporated in a Ga2O3 matrix. The obtained QDs showed a sharp band-edge photoluminescence peak at 557 nm without a broad-defect site emission. The PL quantum yield (QY) of such QDs was 58%, being much higher than that of AIGS QDs without Na+ doping, 29%. The obtained Na-doped AIGS/Ga2O3 composite particles were used as an emitting layer of green QD light-emitted diodes. A sharp electroluminescence (EL) peak was observed at 563 nm, being similar to that in the PL spectrum of the QDs used. The external quantum efficiency of the device was 0.6%.
RESUMEN
Metal oxide TFT fabrication based on a solution-processing method is considered a promising alternative to conventional vacuum processing and has a number of advantages such as low cost, large-area fabrication, and process simplicity. A simple and reliable, direct patterning method for obtaining a carbon-free aqueous metal oxide film is presented herein. Patterning, which is achieved by selective photoreaction of water molecules under ultraviolet irradiation and by a safe, environment-friendly chemical etching process using a non-toxic organic acid, is followed by an annealing process at a temperature of 350 °C to obtain carbon-free metal oxide TFTs. In-Ga-Zn oxide (IGZO), TFTs on SiO2 dielectrics that were fabricated with a direct patterning method exhibited an average mobility of 4.3 cm2/V·s with good uniformity, which is comparable to TFTs formed by conventional photolithography. The TFTs exhibited stable performance with small (within 0.5 V) shifts in switch-on voltage under positive and negative bias stress. Fabrication of flexible IGZO TFTs by direct patterning was also achieved.
RESUMEN
Organic field-effect transistors with hydrogen-bonded diketopyrrolopyrrole-thiophene co-oligomers were fabricated by a solution-process method with annealing at 200 °C, showing ambipolar charge-carrier transfer with field-effect mobilities up to µ(h) = 6.7 × 10(-3) cm(2) V(-1)s(-1) and µ(e) = 5.6 × 10(-3) cm(2) V(-1) s(-1).