Optoelectronic Properties And Stability Of Organic-inorganic Perovskite Materials

Perovskites have very excellent crystallographic characteristics and optoelectronic properties.Organic-inorganic perovskites can combine the respective performance advantages of organic and inorganic components at the molecular level,thus they have been extensively researched because of excellent performance and broad application prospects.Due to the three-dimensional organic-inorganic halide perovskite has been successfully used as the light absorption layer of solar cells,more and more scientific researchers have fabricated new perovskite materials through experimental research and theoretical calculations.Organic-inorganic halide perovskites not only attract the attention of scientist in the field of photovoltaic devices,but also have a wide range of applications in other optoelectronic devices represented by light-emitting diodes and optical sensors.Therefore,a thorough understanding of the carrier dynamics and electric properties of organic-inorganic perovskite materials is essential for the development of optoelectric devices based on perovskite materials.However,one of the challenges hindering the widespread commercialization of perovskite solar cells is the moisture stability of perovskite film.Hence,the problem of moisture stability also needs to be solved urgently.This article mainly does the following work for the above problems:1.This paper mainly researches organic-inorganic perovskites(MA)₂ PdBr₄.Two perovskite films are successfully synthesized with different solvents HBr and DMF,It is found that the carrier recombination process is mainly band-edge recombination by optical pump-terahertz probe spectroscopy,while the carrier recombination time of the sample with HBr as the solvent is shorter because it contains more impurities and recombination rate is faster.2.Then the original material is doped with different amounts of phenethylammonium bromide(PEABr,wherePEA⁺=C₆ H ₅CH ₂CH₂ NH₃⁺)to improve the water stability of the perovskite.Through X-ray diffraction and UV/Vis absorption spectrum,it was found that no matter what exposed to environment of which the relative humidity is 80%or 30%,the perovskite doped-1PEABr has a wonderful water stability about one month,which is greatly improved compared with the original material of which the stability just one day.In addition,by exploring the optical properties of this group of samples,it is found that the 1PEABr sample has strong blue absorption and its photoluminescence spectrum is red-shifted,indicating that the film quality of the sample has improved,which is consistent with scanning electron microscopy images which display 1PEABr has the most uniform and dense surface morphology.3.Next,the complex conductivity of this group of samples are studied by terahertz time-domain spectroscopy,and they are well fitted by Drude-Smith model.Due to the effect of trap passivation and exciton recombination,1PEABr has the highest real part of complex conductivity which reaches 15?^-1c m^-1.Morever,we find that 0PEABr perovskite film has the highest carrier density and 1PEABr has the highest carrier density mobility.Due to the addition of PEABr,the carrier density decreases.4.Finally,we successfully fabricare solar cells using this group of perovskites as the light absorption layer.The current-voltage(J-V)characteristics of devices are investigated under AM1.5G solar irradiance.It was found that OPEABr has the highest short-circuit current density of 0.02174 m A/cm².With the increase of doped-PEABr,the short-circuit current density decreases and the fill factor and photoelectric conversion efficiency have a similar trend.