Preparation Of CsPbI₃ Perovskite Solar Cell Based On SnO Hole Transport Layer

Organic-inorganic hybrid perovskite materials have excellent photoelectric characteristics,and the photoelectric conversion efficiency?PCE?of the corresponding solar cells?PSCs?has been comparable to traditional crystalline silicon solar cells.However,there are still many challenges to achieve the commercial application of PSCs:On the one hand,the commonly used organic hole transport layers materials?HTLs?have high cost and low stability,which need to be replaced by suitable inorganic materials.On the other hand,the current organic-inorganic hybrid perovskite materials have poor moisture and thermal stability,which affect the performance of the devices.For those reason,-the research of all inorganic PSCs has become a hot spot rapidly,among which Cs Pb I₃is the leader.However,in order to obtain high-efficiency Cs Pb I₃-based PSCs,it is necessary to solve the phase instability problem of the Cs Pb I₃itself and explore carrier transport layer materials with matching the energy levels of Cs Pb I₃.In this thesis,p-type Sn O thin films were first prepared by electron beam evaporation,and the effects of deposition parameters and annealing conditions on the properties of the thin films were studied.Then,the Cs Pb I₃thin films were prepared using the solution method,and the effect of PVP additive on the stability of the films was studied mainly.Finally,the Sn O thin films were used as HTLs to construct the Cs Pb I₃solar cell,and the characteristics of the cell were analyzed through theory and experiment.The paper mainly includes the following contents:?1?Preparation and properties of Sn O thin films.The p-type Sn O thin films can be obtained by increasing the substrate temperature or vacuum annealing temperature.At the substrate temperature of 400?,the hole mobility of the film is1.27cm²·V^-1·s^-1with growth preferentially of?001?crystal phase.With the extension of the growth time,the films change from nano-stacked junction growth to nano-sheet growth;Annealed in the air atmosphere,the conductivity type of Sn O films gradually changes from p-type to n-type with the increase of annealing temperature;Sn O₂heterophase appears when the annealing temperature reaches 500?.?2?The effect of additives on the stability of Cs Pb I₃thin films.The phase transition temperature of the pure Cs Pb I₃film is 330?,and it quickly changes to a non-perovskite phase upon air atmosphere.After adding 5%Ca I₂,the black metastable phase was formed at the annealing temperature of 163?,and then changed to yellow phase at 188?.The phase transition temperature of the Cs Pb I₃film added with 66?l of HI solution is reduced to 100?,and it can be stable in the air with a humidity of 60-70%for certain time.The phase transition temperature of the PVP-added Cs Pb I₃film is 140?,and the stability of the perovskite phase of the Cs Pb I₃film in air increases with the increase of the concentration of PVP.?3?Preparation and performance study of Cs Pb I₃-PSCs.Theoretical simulation results show that the valence band of the p-type Sn O thin film matches the valence band of the Cs Pb I₃layer,which is beneficial to the extraction of holes and high PCE can be obtained.The experimentally prepared inverse Cs Pb I₃-PSCs,because of the large amount of PVP remaining in the absorption layer,increase the series resistance of the cells,which is not conducive to the transmission of photo-generated carriers,leading to a small J_SC.However,due to the passivation of PVP on the grain surface,the surface recombination is reduced,and the high V_OCof the PSCs is obtained.