Fabrication Of Light Emitting Diodes Based On CdSe Quantum Dots And Their Optoelectronic Characteristics

Quantum dots have attracted widely attention due to their application in the aspect of biotechnology, solar cells and light-emitting diodes. The advantages of colloidal quantum-dot light-emitting diodes are low turn-on voltage, color purity, energy saving, color size-tunable and low-cost solution method preparation, which show great potential applications in solid-state lighting and display areas. But it also needs to improve the brightness and lifetime to meet the commercial requirement. Currently, the main routines to improve the performance of device including adapt new device structure, develop novel quantum dots and charge transport materials to optimize carriers injection. This article mainly focuses on the performance of QLED influenced by charge transport layers(CTLs) and quantum dot layers.At first, we successfully fabricated all inorganic CTLs QLED through solution spin-coating method. All inorganic CTLs can avoid the degradation of organic CTLs in air, which can enhance the stability of device. We analyzed the main reasons of low performance of device. The solution spin-coating method provides a low-cost way to fabricate all inorganic charge transport layers QLED.At second, the performances of hybrid structure QLED influenced by different electron and hole transport layers were investigated. For ETLs, the QLED based on ZnO ETL showed improved luminance and lower turn-on voltage compared with TiOx ETL based QLED. For HTLs, the QLED based on polymer Poly-TPD HTL are superior to PVK HTL based QLED. We also investigate small molecule TPD doped in polymer Poly-TPD and PVK as HTLs. On the contrary, polymer doped small molecule TPD as HTLs decreased the performance of QLED. The reasons were analyzed by combination the test results.Thirdly, we attempted to synthesis CdSeZnS alloyed quantum dots with chemical composition gradients by single-step method. The CdSeZnS alloyed quantum dots emission peak of PL spectrum was 481 nm, which located in the blue wavelength range. Then the CdSeZnS alloyed quantum dots were used as emission layer in hybrid structure QLED and the photoelectric properties of QLED were measured.