Effect of Hole Mobility Through Emissive Layer on Temporal Stability of Blue Organic Light‐Emitting Diodes

Abstract

Light‐emitting conjugated oligomers comprising anthracene, naphthalene, and fluorene units have been synthesized to investigate three configurations of blue organic light‐emitting diodes (OLEDs) that are designed to identify the origins of device instability. The transient OLED technique is employed to measure hole mobilities, which are found to be 3.1 × 10–4, 8.9 × 10–5, and 3.6 × 10–5 cm2 V–1 s–1 for three different blue‐light‐emitting model compounds with varying fluorene content. A higher hole mobility through the emissive layer results in a wider recombination zone, which, in turn, is responsible for a longer device lifetime and a lower drive voltage at the expense of luminance yield.

The Simple Way to Solution‐Processed Multilayer OLEDs – Layered Block‐Copolymer Networks by Living Cationic Polymerization

“…This counter ion has to be provided by the PEDOT layer, but this is highly unlikely for the polymeric PSS -. It is known that under acidic conditions aromatic sulfonic acids may decompose generating HSO 4 À and SO 4 2À ions. [27] Generation of sulfate ions has been detected in PEDOT-films at temperatures > 100 8C.…”

Highly Luminous Sky-Blue Organic Light-Emitting Diodes Based on the Bis[(1,2)(5,6)]indoloanthracene Emissive Layer

“…77 A higher mobility through the emissive layer provides a wider recombination zone, which is found to be responsible for longer OLED lifetimes and lower drive voltage at the expense of luminance yield. 78 Solid films of 4 indicate the hole mobility equal to μ = 10 -3 cm 2 V -1 s -1 (Figure 5a). Such a hole mobility allows 4 to be used as the hole-transport layer 90V 85V 80V 75V 70V 65V 60V 55V 50V 45V 40V 35V 30V 25V 20V 15V 10V 5V T ime, s C urrent dens ity, mA /cm where the interplane distance was found to be equal to 3.55 Å and taking into account the broad nature of the corresponding XRD reflex.…”

Color Pure and Stable Blue Light Emitting Material Containing Anthracene and Fluorene for OLED

“…Fluorene also has a number of advantages, including its capability to emit in the blue part of the visible spectrum, chemical and photochemical stability, easy synthesis with high purity, liquid crystalline properties and durability under operation in a LED. [12][13][14][15][16] Recently, we reported 9, 10-bis-(9',9'-diethyl-7'-diphenylamino-fluoren-2'-yl)anthracene (BDDFA) which are composed of antharcene and diphenylamino-fluorene group. The multilayer organic EL device constructed using 2% BDDFA as dopant in host produces a bright blue emission with maximum efficiency of 4.17 cd/A and exhibits a blue CIE (Commission Internationale de l'Eclairage) chromaticity coordinates.…”