Study of efficient and stable organic light-emitting diodes with 2-methyl-9,10-di(2-naphthyl)anthracene as hole-transport material by admittance spectroscopy

An organic light-emitting device with enhanced efficiency sby employing 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) as hole-transport material (HTM) has been developed. The admittance spectroscopy studies indicate that using MADN as HTM can reduce the amount of hole carriers injected into the device leading to a well-balanced carrier recombination. The green fluorescent 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-benzo[l]pyrano-[6,7,8-ij]quinolizin-11-one doped tris(8-quinolinolato)aluminum device achieved a current efficiency of 21.8 cd/A and a power efficiency of 10.4 lm/W at 20 mA/cm(2) that are 65% higher than those of the control device. The green-doped device also achieved a long half-decay lifetime of 22 000 h at an initial brightness of 500 cd/m(2).