摘要
High-efficient saturated red light-emitting diodes are realized based on a bilayer of phenyl-substituted poly [p- phenylene vinylene] derivative （P-PPV） and copolymer （PFO-DBT15） of 9,9-dioctylfluorene （DOFF） and 4,7-di- 2-thienyl-2,1,3-benzothiadiazole （DBT）. External electrolurninescent （EL） quantum efficiency of PFO-DBT15 is increased from 1.6% for a single-layer device to 4.7% for the bilayer device by insertion of a P-PPV layer between PEDOT （polyethylene dioxythiophene-polystyrene sulfonic acid） and PFFO-DBT15 at the current density of 35 mA/cm^2. The luminescence efficiency reaches 0.83 cd/A, and the Commission Internationale de PEelairage coordinates （CIE） become nearly x = 0.700 and y = 0.300. In comparison with the devices from PFFO-DBT15 and P-PPV blend films, the P-PPV/PFO-DBT15 bilayer device shows higher EL quantum efficiency and better stability under high current density, The improved device performance can be attributed to the charge-confinement effect at the interface of the P-PPV/PFO-DBT15 bilayer structure.
High-efficient saturated red light-emitting diodes are realized based on a bilayer of phenyl-substituted poly [p- phenylene vinylene] derivative （P-PPV） and copolymer （PFO-DBT15） of 9,9-dioctylfluorene （DOFF） and 4,7-di- 2-thienyl-2,1,3-benzothiadiazole （DBT）. External electrolurninescent （EL） quantum efficiency of PFO-DBT15 is increased from 1.6% for a single-layer device to 4.7% for the bilayer device by insertion of a P-PPV layer between PEDOT （polyethylene dioxythiophene-polystyrene sulfonic acid） and PFFO-DBT15 at the current density of 35 mA/cm^2. The luminescence efficiency reaches 0.83 cd/A, and the Commission Internationale de PEelairage coordinates （CIE） become nearly x = 0.700 and y = 0.300. In comparison with the devices from PFFO-DBT15 and P-PPV blend films, the P-PPV/PFO-DBT15 bilayer device shows higher EL quantum efficiency and better stability under high current density, The improved device performance can be attributed to the charge-confinement effect at the interface of the P-PPV/PFO-DBT15 bilayer structure.
基金
Supported by the National Key Basic Research and Development Programme of China under Grant No 2002CB613405, and the National Natural Science Foundation of China under Grant No 50433030.
