Highly Efficient Organic Light Emitting Diodes with Hole Injection Layer of Thermally Evaporated Molybdenum Oxide

Abstract

LiNi1−yM{y}O{2} specimens with compositions of LiNiO2, LiNi0.975Ga0.025O{2}, LiNi0.975Al0.025O2, LiNi0.995Ti0.005O2 and LiNi0.990Al0.005Ti0.005O2 were synthesized by wet milling and solid-state reaction method. All the synthesized samples possessed the α-NaFeO structure of the rhombohedral system (space group; \(R\bar 3m\)) with no evidence of any impurities. Among the α-LiNiO2 cathodes prepared with the weight ratios of LiNiO2: acetylene black: binder = 85≠10≠5, 85≠12≠3 and 90≠7≠3, the cathode with the weight ratio of 85≠10≠5 had the best cycling performance, with a discharge capacity degradation rate of 1.06 mAh/g/cycle and a discharge capacity at n=20 of 143.5 mAh/g. Among all the samples, LiNi0.990Al0.005Ti0.005O2 had the highest first discharge capacities at 0.1 C, 0.2 C and 0.5 C rates. That sample had the smallest R-factor value, indicating that it had the lowest degree of cation mixing. Among all the samples, LiNi0.975Al0.025O2 showed the lowest rate of decrease in the first discharge capacity with C rate. The first discharge capacities at 0.1 C, 0.2 C and 0.5 C rates were 170.5 mAh/g, 155.0 mAh/g and 124.2 mAh/g, respectively.