A very simple and chromatic-stable white organic light-emitting diode with a colour conversion hole injection layer based on solution process

A chromatic-stable and easily fabricated white organic light-emitting diode with a colour conversion hole injection layer (CC-HIL) has been investigated. The emission layer (EML) was composed of the fluorescent dye p-bis(p ? N,N-diphenyl-aminostyryl)benzene doped into the host 2-(t-butyl)-9,10-di(2-naphthyl)anthracene. A red fluorescent polymer poly(2-methoxy-5-[2'-ethylhexyloxy]-p-phenylenevinylene) (MEH-PPV) with hole transport characteristics and relatively high absorbance to blue electroluminescence was used as the CC-HIL. The CIE colour coordinates at (0.33, 0.35) almost remained unchanged under driving current densities from 20?mA?cm?2 to 400?mA?cm?2 while the current efficiencies reached 3.5?cd?A?1 and 4.65?cd?A?1 at 20?mA?cm?2 and 400?mA?cm?2, respectively. The improved performance was attributed mainly to an enhanced out-coupling efficiency and better carrier balance in the EML.