Improved Performance of Organic Light-Emitting Device with Anatase TiO2 Anode

An organic light-emitting device (OLED) with a Nb-doped anatase TiO2 thin film on a LaAlO3 substrate as an anode shows higher performance than OLEDs with a rutile TiO2 anode. The OLED structure is TiO2/poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/N,N'-di-[(1-naphthalenyl)-N,N'-diphenyl]-(1,1'-biphenyl)-4,4'-diamine (α-NPD)/tris(8-hydroxyquinoline) aluminum (Alq3)/LiF/Al. The maximum luminance is about 3200 cd/m2 at 20 V, and the current efficiency is approximately 2–3 cd/A, which is comparable to that of a reference OLED with an Sn-doped In2O3 (ITO) anode. We speculate that the improvement of the OLED performance comes from the low resistivity with a relatively low electron density of anatase TiO2.