Preparation And Characterization Of Solar Cells Based On Crystal Regulation Of Organic And Inorganic Hybrid Perovskite

In the past decade,organic-inorganic hybrid metal halide perovskite materials have attracted much attention due to their excellent photoelectric performance,low raw material cost,and applied for flexible device.But its long-term stability cannot meet the requirements of industrialization yet.This is mainly due to the fact that the perovskite films prepared by solution method have a large number of defects such as dislocations,vacancies,impurities and suspension bonds.In addition,the halogen ions in its crystal structure may move under working condition,accumulating charges at the interface and intensifying the recombinations.Thus,the long-term stability of the device is affected.In order to improve the performance of perovskite solar cells,this paper mainly uses the strategy of perovskite crystallization regulation to prepare high-quality perovskite thin film,and then carries out the preparation and characterization of the corresponding solar cells,main work is as follows:（1）Firstly,multiple factors affecting the open circuit voltage,short circuit current,filling factor and photoelectric conversion efficiency of perovskite solar cells were analyzed,including series resistance,shunt resistance,interface-defect and bulk-defect assisted recombinations.Secondly,the characterization of technology and methods of perovskite films and devices are introduced,including the chatacterization of photoelectric properties,such as the transient absorption spectrum applied to the transfer of carrier between different layers,photoluminescence technology to perovskite films;Defect characterization,such as the Mott-Schottky method used to testing the built-in voltage,X-ray diffraction,deep-level bulk defect characterization,etc.Charge transport performance characterization,such as electrochemical impedance spectroscopy to characterize the recombination impedance of different devices and carrier transport resistance,transfer resistance,etc.（2）The influence of guanidine hydriodate on the properties and structure of MAPb I₃perovskite film was explored.It was found that there exists strong chemical reaction ability between GA and Pb I₂,and there was almost no lead iodide phase in the film.GA would partially replace MA to expand the lattice and widen the band gap of the film.Secondly,the perovskite solar cells with the stoichimetries of GA（MA）_nPb_nI_3n+1（n=19）and GA_0.14MA_0.86Pb I₃were studied.For the former,isopropyl potassium xanthate was added into the precursor solution of perovskite to improve the quality of the GA-doped films.The photovoltaic conversion efficiency reached 21.3%.For the latter,we adopted the two-component solution method to reduce aging effect of the solution,improving the film formation of GA_0.14MA_0.86Pb I₃perovskite film.At the same time,the deposition of PCBM between Sn O₂and perovskite eliminated the hysteresis and improved the stability of the device for lighting test,which made the SPO reach 17.6%after 250s.（3）The additive assisted film forming strategy was adopted to improve the crystal quality of perovskite by introducing dimercaptan additive into the perovskite precursor solution,thus improving the PCE and stability of the solar modules.The results show that the chemical bond tends to form between Pb²⁺and dimercaptan after the introduction of dimercaptan additive,which makes perovskite crystals coarser during thermal annealing.The addition of dimercaptan inhibits the formation of inactive impurities such as yellow hexahexagonalδ_Hphase and Pb I₂.Therefore,the carrier lifetime perovskite films containing dimercaptan additives（especially for the hexan-1,6-dimercaptan）is increased by more than 4times,and the PCE of perovskite solar modules reach 18.1%.Compared with the modules without additives,the stability of perovskite solar modules is also significantly improved.