| A lot of attention has been drawn to nanomaterials due to their unique sizes and properties as well as potential applications. Up till now, a large number of reports on nanomaterials have been available, however, nanomaterial is a tremendous research field, and there is still a big room to be explored and expanded. One of the most important targets that fabricated nanomaterials using simple and low-cost techniques will be applied in their related fields, a great number of works will still demand to be carried out, and many related problems are necessary to be solved in this area.In this dissertation, several small-molecule organic nanomaterials and ZnO nanomaterials with low-dimensional nanostructures were fabricated, their optical properties were investigated. In addition, several photodiodes and inverted solar cells were achieved by fabricated ZnO nanomaterials combined with several organic semiconductors. The main points are listed as follow:1. Three small-molecule organic nanomaterials include perylene, DCM, DPA were fabricated by reprecipitation, under proper fabrication conditions, perylene nanosheets, DCM nanoparticles and DPA nanocrystals can be formed, their optical properties were investigated. The results showed that the absorption spectra of DCM nanoparticles compared to that of a diluted solution, the intramolecular charge transfer (CT) peak was blue-shifted due to H-aggregation. Moreover, the fluorescence quenching of DCM nanoparticles was observed, resulting from H-aggregates and the twisted conformations of chromophores in the nanoparticles. The change of lattice-state in perylene nanosheets and the formation of J-aggregation in DPA nanocrystals were obtained.2. ZnO nanoparticle has some advantages such as high surface area, superior photoelectric properties and facile synthesis. Using the chemical reflux route, ZnO nanoparticles with various sizes ranging from 5 to 40 nm were synthesized by tailoring reflux time, their crystalline structures and optical properties were investigated. The mechanism of ZnO nanoparticles formation with different sizes was also illustrated.3. Well-aligned ZnO nanorod or nanowire arrays are highly desirable for potential applications in large-area, low-cost and high performance optoelectronic devices. Well-aligned ZnO nanowire arrays (ZNWAs) were grown on ITO-coated glass substrates by chemical bath deposition method. We investigated the effect of concentration of precursors, growth temperature and time, pH value as well as seed layer on the sizes (diameter and length) and packing density of ZnO nanowires. At the same time, well-aligned ZnO nanorod arrays (ZNRAs) were grown on ITO-coated glass substrates, the effect of growth time on the diameter of ZnO nanorods was studied. Additionally, their crystalline structure and optical properties were investigated,. Some factors that were used to regulate diameter, length and packing density of ZnO nanowires or nanorods, and ZnO nanowire or nanorod arrays with high optical transmission in visible light region were achieved.4. The inorganic/organic hybrid optoelectronic device is an interesting field. We fabricated six photodiodes using as-prepared ZnO nanoparticles and well-aligned ZNWAs combined with CuPc, pentacene and P3HT, respectively, their characteristics in dark and under illumination were investigated in detail. The results showed that their J-V characteristics in dark and under various illumination intensity exhibited good rectifying behaviors. Moreover, ITO/ZNWAs/spin-coated P3HT/Ag device displayed an ideality factor of 1.8 and a rectification ratio (RR) of 3211 in dark, this device had the best diode properties among them. Such a high value of RR is attributed to two main factors. One is that the well-aligned ZNWAs display good transport properties consisting of high electron mobility and providing the electrons with a direct electrical pathway. The other is the formation of large intimate ZNWAs/P3HT interface in the device, there are few leakage pathways in this device. A low value of ideality factor indicates that the charge transport mechanism in this device only consists of recombination and diffusion.5. Organic solar cells have stimulated intense research interests due to their noticeable advantages, e.g. low cost, light weight and flexible substrates. However, the short operational stability and lifetime in the ambient atmosphere still remain one of the key problems of organic solar cells that will need to be solved. We fabricated four solar cells with inverted structure using as-prepared ZnO nanoparticles, ZnO nanocrystals (nc-ZnO), well-aligned ZNWAs and ZNRAs combinated with P3HT:PCBM, respectively. The initial power conversion efficiencies (PCE) of these devices were 0.28%, 0.89%, 0.91% and 1.11%, respectively, after they stored in the ambient atmosphere for 4416 h, their PCE were 0.42%, 0.75%, 1.21% and 1.98%, respectively. Besides the PCE of ITO/nc-ZnO/P3HT:PCBM/MoO3/Ag device slightly decreased, the PCE of the other devices increased, suggesting that these solar cells showed long-term good operational stability in the ambient atmosphere. In additon, the reasons that resulted in these solar cells with long-term good operational stability in the ambient atmosphere were systematically analyzed and investigated. Meanwhile, the performances of all devices were compared, the reasons that resulted in the difference from their performances were systematically analyzed and investigated.
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