Highly efficient MEH-PPV-POSS based PLEDs through optimization of charge transport

We demonstrated highly efficient devices based on well-known poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] end capped with POSS (MEH-PPV-POSS) polymer by combining of two approaches: (i) inserting of electron transport material (ETM) either between the emissive layer and cathode or into the emissive polymer, and (ii) doping of polymer with quantum dots (QDs). In order to overcome some handicaps, such as interchain interaction and imbalanced charge carrier fluxes, copper indium disulfide (CuInS2) QDs were incorporated into the polymer matrix, while N-arylbenzimidazoles trimer (TPBi) and 4,7-dipheyl-1,10-phenanthroline (Bphen) were used as ETMs. The best charge carrier balance and color purity were achieved by inserting 0.3 wt% CuInS2 into the polymer and 40 nm Bphen between the polymer and cathode with a current efficiency of 5.1 cd/A and an external quantum efficiency of 1% which is above the average of literature.

► MEH-PPV-POSS based single and double layer devices optimization were investigated.
► CuInS2 or TPBi in the emissive layer reduces FWHM, enhances device efficiency.
► Optimum TPBi doping ratio in MEH-PPV-POSS for enhanced charge transport is 50 wt%.
► 40 nm Bphen between polymer:CuInS2 and cathode leads best charge carrier balance.