| The development and utilization of clean energy has always been a frontier scientific issue in the field of energy science,and solar energy has become a hot topic for researchers because of its inexhaustible advantages.Since perovskite solar cells were first reported in 2009,the device photoelectric conversion efficiency has grown rapidly from 3.8%to 25.7%,which is almost the same as that of crystalline silicon solar cells.However,high-efficiency devices are mainly prepared by organic-inorganic hybrid perovskites,which contain thermally unstable organic cations（such as methylamine（MA+）,formamidine（FA+））,and expensive hole transport layers and noble metal electrodes are required in the devices.For the commercial application of the devices,the stability and cost are also important,so carbon-based all-inorganic perovskite solar cells came into being.So this thesis takes carbon-based all-inorganic perovskite solar cells with low cost and excellent stability as the research object.In order to improve the efficiency of the device,the key point for the preparation of high-quality all-inorganic perovskite films are systematically explored by controlling the crystallization process of perovskite films and passivating the interface defects.The main research contents can be listed as follows:（1）Firstly,Cs Pb I2Br and Cs Pb I2.2Br0.8 perovskite films were prepared by adjusting the composition of the precursor and corresponding perovskite solar cells were prepared by using FTO/Sn O2/PVK/Carbon structure.It is concluded that Cs Pb I2.2Br0.8 C-PSCs has higher short-circuit current density and photoelectric conversion efficiency.Secondly,Cs Pb I3 perovskite solar cell devices were prepared by using FTO/c-Ti O2/m-Ti O2/PVK/Carbon structure.By optimizing the annealing time,it is concluded that the perovskite film annealed for 5 minutes has higher crystal quality,lower defects and appropriate Pb I2 passivator.The corresponding device has higher performance and also exhibits excellent reproducibility.（2）Cs Pb I2.2Br0.8 perovskite films with high quality,large grain size and few defects were prepared by using Pb（Ac）2 doped perovskite precursor and H2O doped IPA antisolvent.The results show that Pb（Ac）2 doping into the perovskite precursor solution will regulate the crystallization growth process of the perovskite film during the high temperature annealing process of the perovskite film and promote the Ostwald ripening process in the perovskite film,so that the small grains grow into large grains.The participation of H2O in the antisolvent IPA will enable the perovskite to quickly form a large number of nuclei in the wet film state,which can provide the necessary conditions for the subsequent Ostwald ripening.The perovskite thin film with large grain size,dense surface and high quality was obtained by the above method.The perovskite solar cells prepared by this film showed a high photoelectric conversion efficiency of 14.31%.（3）A multifunctional interface modifier octylammonium iodide（OAI）is introduced into Cs Pb I3/carbon interface,which can not only reduce the amount of residual Pb I2 at grain boundaries by converting Pb I2 to（OA）2Pb I4 2D phase,but also passivate defects located at the surface and grain boundaries of Cs Pb I3 film.Consequently,greatly reduced defect density of Cs Pb I3 film as well as matched energy-level alignment of Cs Pb I3/carbon interface are achieved,which significantly boost the PCE of Cs Pb I3 C-PSC from 12.97%to 14.64%.Moreover,due to the reduced amount of Pb I2 at grain boundaries and the hydrophobic property of long-chain alkyl in OAI,the unencapsulated Cs Pb I3 C-PSC demonstrates excellent long-term ambient stability,which can retain 91%of its initial PCE after 30 days storage in air. |
