Preparation Of Solar Cells Absorption Layers And Devices Based On In-situ Gas-solid Reaction Method

As a new type of clean energy,solar cells have a broad application prospect.Selecting a suitable approach to fabricate absorption layers of solar cells plays an important role in optimizing the performance of devices.Sulfide quantum dots and perovskite materials,with appropriate bandgap and good photoelectric performance,have become the most potential absorption materials.Chemical bath deposition（CBD）and successive ion layer adsorption reaction（SILAR）,which are main methods to synthesize sulfide quantum dots,have the disadvantages of slow reaction rate and uneven deposition.The most widely-used anti-solvent approach to prepare perovskite films shows poor repeatability and is not suitable for large-scale production.In this thesis,a novel in-situ gas-solid reaction method was developed to prepare the homogeneous binary cadmium sulphide（Cd S）,perovskite CH₃NH₃Pb I₃（MAPb I₃）,ternary I₃-V-VI₄-typed Cu₃SbS₄,ternary I-I-VI₂-typed CuSbS₂ and Ag SbS₂ quantum dots films by controlling the deposition condition and reaction atmosphere,and the structure,morphology of the films and the photoelectric performance of the devices were also explored.In-situ gas-solid reaction method was developed,which includes two main steps of precursor salt solution deposition and gas-solid reaction.By this method,binary cadmium sulfide quantum dots（QDs）with particle size of 2～3nm were successfully deposited on porous titanium dioxide（TiO₂）film,and the obtained TiO₂/Cd S films present smooth surface and uniform distribution.Besides,the liquid and solid Cd S QDS sensitized solar cells by in-situ gas-solid reaction method with the optimized precursor solution concentration of 0.3 M Cd（NO₃）₂ exhibited higher photocurrent densities and photoelectric conversion efficiencies（PCEs）than those by traditional SILAR method.Based on the first-synthesized perovskite crystal（n-C₃H₇NH₃）₆Pb₄I₁₄,methylamine（MA）gas exchanged with the organic cation of（n-C₃H₇NH₃）₆Pb₄I₁₄ by in-situ gas-solid reaction method,and the two-dimensional precursor films converted to three-dimensional（3D）perovskite CH₃NH₃Pb I₃ structure films with large crystal particles（～1μm）and low defect densities.The redundant intermediate products were removed and the precursor converted to 3D perovskite completely with the help of the following heating treatment.The planar perovskite solar cells prepared by the in-situ gas-solid reaction method presented the highest photoelectric conversion efficiency of19.19%,which was significantly higher than those by traditional one-step approach,and they can maintain stable output over 90%of initial power under continuous illumination for 300 s.Pure ternary I₃-V-VI₄-typed Cu₃SbS₄ quantum dots films were fabricated by in-situ gas-solid reaction through optimizing the mixed proportions of precursor solutions CuCl₂ and SbCl₃,heating temperature and heating atmosphere.The Cu₃SbS₄quantum dots with the particle size of 3～4 nm,evenly distributed on porous TiO₂films.In addition,the Cu₃SbS₄ devices prepared by in-situ gas-solid reaction method show good photoelectric response under the illumination,indicating the ternary I₃-V-VI₄-typed Cu₃SbS₄ quantum dots can be used as potential absorption material of solar cells.Ternary I-V-VI₂-typed CuSbS₂ and Ag SbS₂ quantum dots films and devices were prepared by in-situ gas-solid reaction method through optimizing the precursor solutions and spin-coating sequence.In addition,both of the CuSbS₂ and Ag SbS₂devices prepared by the in-situ gas-solid reaction method present excellent photoelectric performance and sensitive photoelectric response under AM1.5illumination.