Efficiency enhancement of 1,1,2,3,4,5-hexaphenylsilole-based organic light-emitting dioades by post-packaging annealing

Organic light-emitting diodes based on the emission of 1,1,2,3,4,5-hexaphenylsilole (HPS) peaking at ~492nm have been fabricated and experienced post-packaging annealing in oven at 70degC for 5 hours. The electroluminescent (EL) characteristics were measured and compared in between the devices with and without annealing. The turn-on voltage (defined as the voltage to require 1 cd/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), luminous efficiency and power efficiency of devices were much improved after this thermal treatment. Crystallization of the HPS film due to annealing and therefore the photoluminescence (PL) quantum yield (Oslash <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PL</sub> ) enhancement and electron mobility increase there of were proposed as the main factors accounting for the EL performance improvement