Performance Optimization Of Quantum Dot LED

Quantum dot materials have been used in the field of luminescence because of their high efficiency and adjustable band gap.The brightness,EQE of QLED(Quantum Light Emitting Diodes)have reached the market-oriented requirements,recently.But QLED want to be truly practical,we also need to consider the stability and work-life of the device;and the QLED device structure determines whether it can be produced on a large scale.From the two aspects,we first improve the all-inorganic hole transport layer and electron transport layer materials,and verify the advantages of the whole all-inorganic QLED in stability and work-life.Then we designed the TOP emission QLED,which greatly improved the efficiency of QLED light emission.And the following are details:1.We modified inorganic hole transport layer and electron transport layer materials to fabricate all-inorganic QLED devices.Due to the mismatch of the material transport ability of the traditional inorganic hole transport layer and the electron transport layer,there has been no obvious breakthrough in the performance of the all-inorganic QLED.We doping Mg elements into common inorganic hole transport layer material NiOx to obtain solution-prepared Mg-NiOx nanoparticles,which improved the carrier transport capacity on the hole side and improved the energy level matching between the hole transport layer and the quantum dots.Meanwhile,we model and analyze the device,match different inorganic electron transport layer materials with Mg-NiOx,compare the change of carrier concentration and carrier recombination rate,and obtain the best all-inorganic QLED device structure.The brightness of all-inorganic red,green and blue QLED devices reaches 38444 cd/m2?177825cd/m2?3103cd/m2,respectively,which is the highest value reported at present.The stability of all-inorganic QLED devices is tested,and its work-life is much higher than that of organic-inorganic QLED hybrid devices,which proves the superiority of all-inorganic QLED devices in stability and work-life,and has broad application potential.2.We prepared the TOP emission QLED.The microcavity structure of the TOP emission QLED is modeled and analyzed to obtain the TOP emission structure suitable for red,green and blue QLED,which maximizes the microcavity effect to improve the light extraction efficiency.We used the self-assembled compound material Hf(ACB1)4 as the capping layer.Through the electrochemical spectral angle offset test and the angular emission intensity test,it is proved that the addition of the Hf(ACB1)4 capping layer effectively improves the shifting of the TOP emission QLED emission spectrum,and makes the emission of the TOP emission close to that of the Lamber light source.