Full‐color nanostructured thin‐film electroluminescent device utilizing ZnS nanocrystals doped with activator‐ions

Abstract

We have studied nanostructured (NS‐) thin‐film electroluminescent (TFEL) devices utilizing the ZnS nanocrystals (NCs) with the mean crystal sizes of ca. 2–4 nm doped with activator‐ions. As compared to the conventional TFEL device, we have achieved a remarkable reduction in the operation voltages by >100 V0–p. Moreover, toward full‐color emissions, EL emissions of three primary colors, i.e., red, green, and blue have been derived from Mn2+, Tb3+, and Tm3+ ions, respectively. In this article, we review the studies on the fundamental properties of ZnS NCs as well as the device performance of the NS‐TFEL devices. We also discuss the excitation mechanisms of the activator‐ions in the ZnS NCs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Structural and electrical properties of Zn1–xCux O thin films

“…Specifically, its application to large-area thin-film devices fabricated on a foreign substrate (e.g. glass and plastic substrates) is attractive because it can serve as an excitation source of phosphors for a lightweight, transparent, and flexible display [3,4]. To realize its application, formation of a highquality p-type ZnO synthesized at a low temperature is desired.…”

An electroluminescence device for printable electronics using coprecipitated ZnS:Mn nanocrystal ink

“…Furthermore, doped II-VI semiconductor NCs with a crystal size (diameter) less than twice the Bohr exciton radius (a exc ) are promising luminescent materials because of their high photoluminescence (PL) efficiencies [4]. ZnS:Mn NCs, in particular, are an attractive candidate for an electroluminescence (EL) material [5][6][7][8][9][10][11][12] because ZnS:Mn phosphor was found to be an efficient emission material for inorganic EL devices [13]. We studied hot-electron-induced EL from ZnS:Mn NCs with a crystal size of 2-4 nm [5][6][7][8][9] using ac voltage driven devices, and demonstrated that the dominant excitation mechanism for EL emission is direct impact excitation [14].…”

On the Large Threshold Voltage Shifts of Nano-structured Thin Film Electroluminescent Devices

“…In both type I and type II NS-TFELD, another peculiar characteristic of the enormous decrease in threshold voltages V th has been reported. 3,[6][7][8] The threshold voltage shift (ÁV th ) of more than 100 V 0{p has been measured 3) and this threshold voltage shift has appeared to a greater extent in type II. 6) Besides, V th of about 11 V 0{p (zero to peak voltage) has been reported.…”