Preparation And Photoelectric Conversion Performance Of Perovskite Solar Cells Based On Inorganic P-type Cuprous Iodide

Because of the energy crisis and environmental issues,humans have an urgent need to seek renewable energy to satisfy the requirements of the sustainable development of society.The solar energy is undeniably considered as an inexhaustible clean energy which received extensive attention of the whole society.In the past seven years,the photoelectric conversion efficiency of solar cells with the halogen lead system（CH₃NH₃PbI₃）has rapidly enhanced from3%to 23%,and its application prospect is very promising.The rapid development of perovskite solar cells is mainly arise from its numerous intriguing attributes,including facile solution method preparation,cost-effective,remarkable properties of light absorption,the appropriate band gap,long exciton diffusion length,bipolar transmission property,and direct band gap,and these properties satisfy all the requirements of high efficiency solar cell devices.This thesis aims to study the photoelectric performance controllable perovskite solar cells based on the inorganic cuprous iodide hole transporting film which prepared by through vacuum thermal evaporation method,reactive sputtering and solution method.We also studied the influence of n-i-p and p-i-n structure on the photoelectric properties of the perovskite solar cells.To further simplify the preparation process,we designed and prepared of the CuI/perovskite bulk-heterojunction solar cells,and explored the effect of the constitution water and chlorine on perovskite crystal grown thermodynamics and kinetics.We obtained the high efficiency devices.The main conclusions are as follows:1.Copper iodide（CuI）thin film grown by a direct vacuum thermal evaporation method is utilized as inorganic hole transport layer in regular structure perovskite solar cell,and the impact of CuI deposition rate on the performance of perovskite solar cells was studied.As the iodine possesses higher vapor pressure than copper,it can easily escapes from the evaporation source and deposit on the substrate,which result in various ratio of I/Cu in CuI film.It is found that the element ratio,morphology and electronic property of the CuI films are all sensitive to the deposition rate.The precise deposition rate was controlled by the applied heating electrical current and monitored.We obtained unique and compact CuI films.The different devices were measured by using transient photovoltage（TPV）and transient photocurrent（TPC）measurements.We draw a conclusion that the extra iodine element can induce significant photocarrier interface recombination,which severely decrease the V_OC of the perovskite solar cells Meanwhile,the photocarriers extraction and transportation were also impaired by the extra iodine element,leading to low FF and PCE.So,extra iodine is not beneficial for the devices’photoelectric property.Furthermore,we prospect that controlling the iodine and its distribution in CuI film is potentially a new way to further improve the performance of CuI based perovskite solar cell.The CuI films prepared by reactive sputtering and solution method were used to assemble p-i-n structure perovskite solar cells.Finally,we achieved an optimal perovskite solar cell with the PCE of 16.56%and no hysteresis effect.2.Proposed hole-transporting materials mixed with perovskite precursor solution,preparation of CuI/perovskite bulk-heterojunction solar cell structure,and researched the effect of incorporated CuI on perovskite grain nucleation,crystallization tendency,and grain growth.We found that the perovskite film blend with CuI component is beneficial for promoting the exciton separation and extraction in heterogeneous interface,high-efficiency transport hole,and,could also passivate perovskite intergranular defects,reduce the radiative recombination,and thereafter improve device photoelectric conversion efficiency.In addition,the impact of different amount of CuI components on the photoelectric physical properties of perovskite films was studied,and 14%photoelectric conversion efficiency was obtained under the optimal preparation conditions.3.We put forward a co-doping strategy of hydrate water and chlorine to obtain the high crystallization orientation,and crystalline perovskite film with annealing time just for 5 min,which greatly shorten the devices’preparation time.The photoelectric conversion efficiency16.59%was achieved under optimal preparation parameters.The effect of hydrate water on perovskite films is a double-edged sword,and the excessive hydrate water seriously impair the crystallinity of perovskite films.The incorporative Cl elements improves the film-forming and crystallization quality of perovskite films.Large grain size is obtained by using the co-doped strategy,which reduces the grain boundary,greatly improves the carriers extraction and transmission rate,and significantly suppress the non-radiative recombination of the photonic carrier.In addition,a simple one-step preparation process is beneficial to the preparation of large area devices.The long-term stability measurement is equally important parameters for evaluation of devices performance.We store the unpackaged devices in the glove box for the long-term stability measurement,and the remaining 80%of the initial efficiency after more than 20 days was achieved,which shows desirable long duration stability.