Abstract
In this thesis, I first studied the exciplex formation in the physically blended organic thin films. By incorporating these exciplex formation organic thin films as the emission layers and the host materials in the devices, a series of organic light emission diodes (OLEDs) were fabricated and optimized. Then, I investigated Br-based organometallic lead halide perovskite films and devices by sequential vacuum deposition process. At last, I studied on perovskite films and devices by solvent engineering. At the beginning, solution-processed organometallic lead halide perovskite solar cells were fabricated and optimized to investigate solvent engineering profoundly. Then, I manufactured and optimized Br-based organometallic lead halide perovskite films by solvent engineering. By utilizing perovskite films as emission layers, I fabricated a series of organic-inorganic hybrid halide perovskite light-emitting diodes (PeLEDs). In the introduction section, I briefly introduced the development, operation principles and measurement methodology of OLEDs. In the second chapter, I studied the photophysics properties of the films composed of physical blending of varios organic materials by solution and vacuum process. The ratios between two carefully selected materials were optimized to enhance the exciplex formation and light-emission properties. The best device showed a luminous efficacy of 36.2 lm/W, a current efficiency of 31.2 cd/A, and an external quantum efficiency (EQE) of 9.9%. I also demonstrated fluorescent and phosphorescent solution-processed and vacuum-processed OLEDs utilizing exciplex-formation hosts. The best phosphorescent OLED showed a luminous efficacy of 50.3 lm/W, a current efficiency of 44.8 cd/A, and an EQE of 19.4%. In the third chapter, I made Br-based organometallic lead halide perovskite films by sequential vacuum deposition, and tried to dope the perovskite materials into organic host materials to realize energy-transfering host-guest system. The light-emitting devices with these perovskite-doped films as the emission layer only exhibited blue light from the organic host materials. There was no trace of energy transfer between the organic-inorganic hybrid halide perovskites and the organic materials. Then, I turned to fabricate vacuum-processed light-emission devices with pure Br-based organic-inorganic hybrid halide perovskite as the emission layer. However, these devices didn’t exhibit any light-emitting property. The reason may be ascribed to the oversize of the perovskite crystals. In the forth chapter, we manufactured solution-processed organometallic lead halide perovskite films with lead acetate (Pb(OAc)2) and methylammonium bromide (MABr) as precursors along with solvent engineering process. First, to understand the mechanism of solvent engineering, organic-inorganic hybrid halide perovskite solar cells were fabricated by solution process along with solvent engineering process. After optimizations, I successfully fabricated uniform perovskite films. The solar cell utilizing these films as the active layer achieved a VOC of 0.852 V, a JSC of 21.73 mA/cm2, a fill factor of 0.635, and a power conversion efficiency of 11.8%. Besides, I found that spin speed of perovskite film strongly influences the property of perovskite film and the performance of the devices Then, I started the study of perovskite film made from Pb(OAc)2 and MABr. After optimizing the ratio between two precursors to prevent the presence of Pb atoms, we fabricated a series of PeLEDs. The optimized PeLEDs with sputtered nickel(II) oxide (NiO) as hole transporting layers exhibited a stable performance and reached a maximum luminance of 906 cd/m2, a luminous efficacy of 3.5 lm/W, a current efficiency of 8.6 cd/A, and an EQE of 2.7%.