Controllable Preparation Of Organic-inorganic Hybrid Perovskite Materials And Its Application In Luminescent Devices

Organic-Inorganic Hybrid Perovskite Materials have increasingly received considerable attention due to their exceptional optoelectronic properties.This upsurge was initially driven by the perovskite solar cell,which achieved a remarkable power conversion efficiency above 20% in the short term.As people's understanding and awareness of new materials,based on research areas of perovskite material has begun to expand,Its potential applications in the field of luminescence allowed the researchers to see new hope in the preparation of high-brightness light-emitting diode?LED?and lasers.As they have an optical bandgap that is tunable in the visible to near-infrared regions,combined with their low-temperature solution-processed method,so these materials can also be deemed as ideal candidates for light-emitting devices applications.The appealing properties of such emerging materials that might enable advances in perovskite-based electroluminescent devices are a high quantum efficiency,wavelength-tunable emissions,ambipolarcharge transport characteristic,and a rather high color purity.It is possible to be widely used in the fields of display,lighting and optical communication in the future.In this paper,we prepared organic-inorganic hybrid perovskites CH3NH3 Pb I3 and CH₃NH₃PbBr₃,optimized material synthesis conditions and analyzed its properties of morphology,crystal and optical.We further designed and prepared the CH₃NH₃PbBr₃ based green LED,and its electrical properties and stability were investigated.The main research results include:1.We have synthesized perovskite thin film CH₃NH₃PbI₃ by using a two-step spin-coating technique.Prepared a high quality CH₃NH₃PbI₃ thin film by varying the high spinning speed of Pb I2,of CH₃NH₃PbI₃ and the ratio of CH3NH3 I to Pb I2.The results show that the prepared thin film have low defect density,high phase purity and excellent luminescence properties,and are suitable for being used as luminescent layer in light-emitting devices.Further,temperature-dependent photoluminescence measurement was performed,and a structural phase transition and the exciton radiative recombination process were revealed,which lead us have a deeper understanding of perovskite materials.2.We have synthesized perovskite thin film CH₃NH₃PbBr₃ by using a one-step spin-coating technique.Optimized conditions such as varying the spinning speed and the annealing temperature of the film or using DMF/HBr cosolvent can not make the films both have a good morphology and optical properties.So the gas assisted solution method was used,and by varying the time and temperature in the evaporation process,the CH₃NH₃PbBr₃ thin film which have a high coverage density and excellent luminescence properties were prepared.3.The CH₃NH₃PbBr₃ thin film has a remarkable morphology and optical properties prepared by using a two-step spin-coating technique.Furthermore,green LEDs based on ZnO/CH₃NH₃PbBr₃/PEDOT:PSS were fabricated.The electrical characteristics were analyzed,and a turn-on voltage of the device is 2.8V,and the EQE of the device reaches 0.0645% under the voltage of 9.0V were obtained.Although the results were far from expected,it still has a room for improvement.In addition,the stability of the diode is investigated and analyzed.It is found that the performance of the device has a high sensitivity to the ambient atmosphere,and the decay of the luminous efficiency is irreversible.We believe that the effectively solution on the problem that the luminescent layer is sensitive to the environment,more optimization on the structure design of the device and increasing the device stability,the preparation and application of perovskite based light-emitting diodes will be full of hope in real life.