CuO/Se, Cs₃Sb₂Br₉ Thin Films And Solar Cells

Improving the performance of existing photovoltaic materials and exploring new photovoltaic materials are two basic approaches for the research and development of solar cells.CuO with suitable band gap(～1.4 eV)and the large absorption coefficient of light(106 cm-1)is a promising photovoltaic material.However,since CuO has a high melting point and decomposes near the melting point,it cannot be prepared by vacuum thermal evaporation and improved its crystallinity by high-temperature annealing method.CuO film prepared by the prior technologies(magnetron sputtering,chemical solution,etc.)has poor crystallinity and a lot of defects,which results in the serious carrier recombination and low photovoltaic conversion efficiency.The development of all-inorganic perovskite solar cells is expected to overcome the poor stability of organic-inorganic hybrid perovskite solar cells.In this thesis,the research on improving the crystal quality and photoelectric properties of CuO films and all inorganic Cs3Sb2Br9 double perovskite films and solar cells were carried out.The main study results are as follows:1.A novel CuO/Se composite film was prepared by introducing Se with a low melting point of 221℃ into CuO using low temperature annealing(near the melting point of Se)for the first time.The hollow holes and dangling bonds are reduced or eliminated via infiltrating CuO by molten Se,thereby greatly reducing defects in the film.The CuO/Se composite film combines the advantages of CuO and Se(CuO has strong absorption of light,suitable gap;Se has low melting point 221℃ and is suitable for low temperature preparation and processing.It also has strong photosensitivity),and overcomes their shortcomings(CuO has a high melting point and is easy to decompose;the band gap of Se is too large,～1.8 eV).The CuO/Se film has strong absorption of light throughout the entire solar spectrum(average absorption is close to 80%),and its photo-generated carrier diffusion length is particularly large(3.147 mm),much larger than that of the best p-type single crystal silicon(1.95 mm).The carrier diffusion length of CuO/Se film is also much larger than the organic-inorganic hybrid perovskite material(the carrier diffusion length of single crystal CH3NH3PbI3 is 0.32 mm,and polycrystalline film is 0.014 mm).The photoelectric conversion efficiency of the solar cell Glass/FTO/TiO2/(CuO/Se)/Au has reached 9.11%based on the prepared CuO/Se composite film.2.A method for preparing double perovskite Cs3Sb2Br9 film by annealing a CsBr film in SbBr3 atmosphere is proposed for the first time.The results show that the Cs3Sb2Br9 film has good crystallinity when the CsBr film is annealed at 200℃ for 12 hours.The surface of the film Cs3Sb2Br9 is smooth and compact,and it has no phase change in air for 15 days.The solar cell FTO/TiO2/Cs3Sb2Br9/Au with an efficiency of 0.19%was fabricated for the first time.3.Preparing Sb2Se3 film and solar cells by vacuum thermal evaporation.The Sb2Se3 film with different thickness(300-500 nm)has no obvious change after annealing at different temperatures(400-450℃)and time(5-20 min).The Sb2Se3 film with 500 nm annealed at 450℃ for 10 minutes decomposed.The photoelectric conversion efficiency of the solar cell FTO/TiO2/Sb2Se3/Au is 0.70%,when the thickness of the Sb2Se3 film is 300 nm.