Improved efficiencies in light emitting diodes made with CdSe(CdS) core/shell ty

2019-10-14 14:39:01

The CdS CdSe dependent nanocrystal

责任者: Schlamp, M.C.;Peng, X.;Alivisatos, A.P. 单位: Dept. of Chem., California Univ., Berkeley, CA, USA 来源出处: Journal of Applied Physics(J. Appl. Phys. (USA)),1997/12/01,82(11):5837-42 摘要: We report experiments on bilayer light emitting diodes made with organically capped CdSe(CdS) core/shell type semiconductor nanocrystals and an electroluminescent (EL) semiconducting polymer [poly(p-phenylenevinylene) or PPV]. The devices emit from red to green with external quantum efficiencies of up to 0.22% at brightnesses of 600 cd/m2 and current densities of 1 A/cm2. They have operating voltages as low as 4 V and lifetimes under constant current flow of hundreds of hours. Most of these numbers are significant improvements over similar devices made with CdSe nanocrystals. The devices show either nanocrystal-only EL or a combination of nanocrystal and PPV EL, depending on nanocrystal layer thickness. The nanocrystal EL is dependent on nanocrystal size. Some devices show a voltage dependent spectral output. The spectral output is consistent with a field dependent electron range in the nanocrystal layer limited by carrier trapping 关键词: cadmium compounds;electroluminescence;electron traps;hole traps;II-VI semiconductors;light emitting diodes;nanostructured materials;organic semiconductors;polymers;CdSe-CdS core/shell type nanocrystals;semiconducting polymer;light emitting diodes;poly(p-phenylenevinylene);ITO-PPV-CdSe-CdS-Mg;external quantum efficiencies;brightness;current densities;lifetime;voltage dependent spectral output;carrier trapping;4 V;CdSe-CdS