Synthesis of Fluorescent C2-Bridged Teraryls and Quateraryls for Blue, Skyblue and Green Color Light Emitting Devices

Abstract

Highly fluorescent, stable blue, skyblue and green color light emitting teraryls and quateraryls were prepared from a ketene-S,S-acetal under mild conditions. These compounds exhibited photoluminescence both in solid state and in solution phase with good quantum yields, positive solvatochromic behaviour and reversible oxidation and reduction properties. The electronic characteristics of teraryl 6a, and quateraryls 9a, 9b were examined by time-dependent density functional theory (TDDFT) calculations. The light emitting devices of teraryl 6a, quateraryls 9a, 9b with the configuration of ITO/PEDOT:PSS (40 nm)/NPB (20 nm)/ dye (50 nm)/BCP (7 nm)/ LiF (0.7 nm)/Al (200 nm) were fabricated, which exhibited electroluminescence maxima at 455, 480 and 525 nm respectively. These devices operated at substantially low turn-on voltage (3 and 4V) with maximum luminance efficiency of 0.62, 0.57 and 1.9 cd/A and brightness of 59, 160 and 1284 cd/m2 respectively.