Research On The Preparation And Photoelectric Properties Of Perovskite Solar Cells Based On Tin Dioxide

As the conventional energy resources are limited and environmental problems are becoming prominent gradually, new energy resources, being environmental friendly and renewable, are paid more and more attention by all the countries. In recent years, the development of organic inorganic hybrid halide perovskite leads us into a new era of photovoltaic technology. Its distinctive attributes mainly include the carrier mobility is high, the spectra absorption range is appropriate, the diffusion length is long and the simplicity of preparation, thus creating the photovoltaic, a light emitting diode and laser most has the market competition of optoelectronic materials.The Ti O2-based the perovskite solar cells（PSCs） has been extensively studied, mature,but other metal oxides such as the study of SnO₂ is incomplete. SnO₂ due to its excellent property is expected to become a new generation of electron transport layer.In the wide band gap of semiconductor oxides, band gap of SnO₂ is close to that of Ti O2, and the electron mobility and electron diffusion coefficient of SnO₂ are higher than that of Ti O2, which has the potential to be applied in the PSCs field. In this paper,four kinds of SnO₂ morphology were prepared: two-dimensional nanosheets,one-dimensional nanorods & nanoneedles,zero-dimensional nanoballs, respectively and assembled into PSCs. Additionally, photoelectric properties were studued systematically.The details of the research are as following:（1） With stannous chloride dihydrate as the source of tin, SnO₂ nanosheets were synthesized using hydrothermal method and the morphology and crystal were characterized. By spin-coating, the ultrathin SnO₂ nanosheets are introduced into PSCs as the support layer and the light absorbing material. By optimizing the crystallization time of CH3NH3 Pb I3, the best performance of PSCs can be obtained.The experimental results show that the size of CH3NH3 Pb I3 is about 400 nm and the7.81 % photoelectric conversion efficiency is obtained when the crystal time of CH3NH3 Pb I3 is 10 min. Using Ti Cl4 solution to modify the surface of SnO₂ nanosheets, it is found the photoelectric conversion efficiency improves from 6.86%to 7.81 %. After optimization of SnO₂ film, the total devices get the average efficiency for 7.9 % during the repeatability and stability test, and more than 80 % ofthe efficiency of the devices is greater than 7.5 %. It shows the device has good reproducibility. After the test, the device is placed in the glove box. In 240 h, the device stability is not bad and the device PCE decreasesby 5.2 %.（2） Using tin（IV） chloride pentahydrate as the source of tin, under alkaline conditions via hydrothermal method, SnO₂ nanoneedles and SnO₂ nanorods were synthesized by controlling the additives and were to be assembled into structure of FTO/SnO₂/CH3NH3 Pb I3/Spiro-OMe TAD/Au. The results display the average stability of SnO₂ nanorods is higher than that of SnO₂ nanoneedles, and photoelectric conversion efficiency of SnO₂ nanorods is better. The average photoelectric conversion efficiency of SnO₂ nanorods reaches 3.67 %, significantly higher than that of SnO₂ nanoneedles based PSCs. When SnO₂ nanorods is treated by Ti O2 before and after, the photoelectric conversion efficiency of PSCs reaches 6.08 %, and the average efficiency reaches 5.9 %. In 240 h, in PCE falls 4.4 %, indicating the preparation device is high stability, and the attenuation rate is low.（3） With stannous chloride dihydrate as the source of tin, SnO₂ nanoballs were synthesized by hydrothermal method and morphology and crystal were characterized.The SnO₂ nanoballs with a diameter of about 50–60 nm were introduced into PSCs as a support layer and an electron transport layer. The average photoelectric conversion efficiency of 12.65 % is obtained by optimizing the rotational speed of the Pb I2. The effect of PVP on preparation of SnO₂ nanballs and the influence of the PSCs has been demonstrated and it is found with the addition of PVP, efficiency of the PSCs are higher. After being treated by Ti Cl4 solution, photoelectric conversion efficiency enhances from 8.47 % to 12.11 %. After optimized SnO₂ nanoballs-based PSCs, the PSCs’ average efficiency is 12.12 %, and more than 83% of the efficiency of the devices is over 11.5 %. After the test, the device is placed in the glove box. In 240 h,the device stability is not bad and the device PCE decreases by 9 %.