Chuan-Hsi Liu

General hot-plate heating is used to form a crystal structure of films; however, how to achieve a homogeneous and regulated crystal formation will be a crucial challenge in the future. In this study, based on perovskite-series materials, organic methylamine lead trioxide (MAPbI₃) films doped with inorganic lead iodide (CsPbI₃) quantum dots (QDs) are treated using the rapid thermal annealing (RTA) process in argon gas to break the crystallization barrier. These RTA-treated perovskite quantum dot (PQD) films at various temperatures of 100–160 °C are detected using X-ray diffraction, X-ray spectroscopy, and absorbance measurements to investigate their structural and optical properties as well as their binding states. The experimental results demonstrate that the PQD film annealed at 120 °C has optimized characteristics, revealing better crystallinity and the lowest content of oxygen atoms (31.4%) and C-O-C bonding (20.1%). A too-high RTA temperature, more than 140 °C, causes severe degradation with the existence of PbI₂. A proper RTA process, an alternative to normal heating and annealing, can effectively inhibit the occurrence of degradation and even usefully improve the performance of PQD films.

In this study, a composite perovskite film composed of lead cesium triiodide (CsPbI₃) quantum dots (QDs) and methylammonium lead iodide (CH₃NH₃PbI₃; MAPbI₃) was proposed. The CsPbI₃ QDs prepared by hot-injecting were used as an anti-solvent in precursors to passivate the surface of this composite perovskite film. The further argon (Ar) plasma treatment improves the surface of the film. The effects of the powers from 100 to 200 W on the composite perovskite film structure, chemical element composition, and optical properties were studied. The experimental results demonstrate that the CsPbI₃ QDs passivation boosts the ultraviolet light absorption (350–450 nm) and inhibits the formation of the PbI₂ phase. Furthermore, Ar plasma treatment effectively improved CsPbI₃ QDs passivation on MAPbI₃ film. The powers lower than 140 W cause C=O bonds to dissolve and coordination bonds to form between OA carboxyl moieties and undercoordinated Pb²⁺ ions. At 160 and 140 W, the obvious crystal phase segregation and a decrease in light absorption are observed, respectively. Meanwhile, the strong bombardment of Ar ions at higher than 160 W causes the severe degradation of MAPbI₃ film.

This article demonstrates changes in the structures of poly (3,4-ethylene dioxythiophene): polystyrene sulfonate (PEDOT: PSS) with the addition of organic additives. The mechanisms of PEDOT: PSS are analyzed using X-ray photoelectron spectroscopy (XPS), cross-sectional images obtained from scanning electron microscopy (SEM), and contact angles. In this paper, a bond-breaking reaction and phase separation are successfully found to occur between PEDOT: PSS molecules and the organic additives. Our research also finds that this bond-breaking reaction and phase separation exist in the PEDOT: PSS–sorbitol–maltitol film at the same time. The addition of organic additives will improve the optical properties and the moisture stability of PEDOT: PSS films.

In this study, the inorganic perovskite cesium lead triiodide (CsPbI₃) quantum dots (QDs) produced by hot-injection method were added into the hybrid perovskite methylamine lead triiodide (CH₃NH₃PbI₃; MAPbI₃) to form composite perovskite film. It is not easy for argon (Ar) to react with perovskite. Therefore, argon plasma was used to optimize the properties of the surface. However, methylamine lead triiodide molecular will be degraded by excessive wattage. Therefore, the influence of plasma power acting on composite perovskite film was investigated. The experimental results show that the light absorption capacity can be increased by argon plasma power of 140 watt (W) acting on the surface of films because organic impurities are removed and surface morphology of film is changed.

This article demonstrates the change of structural and optical properties of poly (3,4-ethylene dioxythiophene): polystyrene sulfonate (PEDOT: PSS) by organic additive and acid treatment. The addition of sorbitol and maltitol can disperse the micelles of PEDOT: PSS. The mechanism of the bond-breaking reaction was investigated and a model for the bond-breaking reaction is also proposed. Furthermore, multiple formic acid treatments were found to reduce the PSS content of PEDOT: PSS, resulting in an enhancement in conductivity (4.2 × 10⁴ S/m).

After the preparation of inorganic perovskite cesium lead iodide quantum dots (CsPbI₃ QD) by ligand-assisted reprecipitation (LARP), CsPbI₃ QD was added to the organic perovskite methylamine lead triiodide (CH₃NH₃PbI₃; MAPbI₃) to successfully form composite perovskite film. To obtain better perovskite quantum dot (PQD) crystal characteristics, this research used different annealing temperatures to discuss the crystallinity changes of perovskite quantum dots (PQD). Through X-ray diffraction (XRD) analysis, it was found that the preferred peak (110) of MAPbI₃ had maximum peak intensity when the annealing temperature increased to 120 °C. Based on the measurement results of PQD’s Ultraviolet-Visible spectrum, it was shown that the maximum absorption area was obtained at the wavelength of 350 nm~750 nm at the annealing temperature 120 °C. From the scanning electron microscope (SEM) measurement, it was found that the grain size was the largest at the annealing temperature 120 °C, and the grain size was 60.2 nm. The best crystallization characteristics of PQD were obtained at the annealing temperature 120 °C.

In recent years, the study of organic–inorganic halide perovskite as an optoelectronics material has been a significant line of research, and the power conversion efficiency of solar cells based on these materials has reached 25.5%. However, defects on the surface of the film are still a problem to be solved, and oxygen plasma is one of the ways to passivate surface defects. In order to avoid destroying the methylammonium lead iodide (MAPbI₃), the influence of plasma powers on film was investigated and the cesium triiodide (CsPbI₃) quantum dots (QDs) were doped into the film. In addition, it was found that oxygen plasma can enhance the mobility and carrier concentration of the MAPbI₃ film.

In this study, adding CsPbI₃ quantum dots to organic perovskite methylamine lead triiodide (CH₃NH₃PbI₃) to form a doped perovskite film filmed by different temperatures was found to effectively reduce the formation of unsaturated metal Pb. Doping a small amount of CsPbI₃ quantum dots could enhance thermal stability and improve surface defects. The electron mobility of the doped film was 2.5 times higher than the pristine film. This was a major breakthrough for inorganic quantum dot doped organic perovskite thin films.