Study On The Photo-Stability Of Perovskite Materials And Solar Cells

Organic-inorganic hybrid perovskite is generally applied to the optoelectronic devices profit from its remarkable photoelectric performance and economic cost.Perovskite material was first used in dye-sensitized solar cells as a photoactive layer,which evolved perovskite solar cells.After continuous endeavor by researchers in developing materials,designing devices and adjusting interface energy band,the efficiency of 25.5%of perovskite solar cells has caught up with that of monocrystalline silicon photovoltaic cells.However,the actual employ of perovskite solar cells is still hindered by many factors,which impede its commercialization process.A successful photovoltaic technology not only requires high efficiency at low cost,but also maintains long-term stable power output under working conditions.Because perovskite materials are prone to degradation and failure in outside air environment,the working life of perovskite solar cells is difficult to satisfy actual application requirements.Optimizing the packaging process can effectively isolate the contact of the perovskite with water and oxygen,but perovskite solar cells as photoelectric devices,the impact of light illumination can not be avoided in their working state.Therefore,it is crucial to realize the degradation mechanism of perovskite materials and devices under light illumination.Because the space environment is not affected by water and oxygen,and the advantage of high power per weight and resistance to high-energy particles of perovskite solar cells specifically satisfy the demand of power equipment in spacecrafts.Perovskite solar cells are expected to replace current gallium arsenide solar cells and are used in satellites,high-altitude drones.This paper takes CH₃NH₃Pb I₃perovskite as the research object,and explores the phenomenon of light illumination of perovskite materials and devices in a vacuum environment and the mechanism behind it.The research content of this thesis is mainly divided into two parts:1.The degradation rate and decomposition products of the perovskite film are significantly diverse under red,green and blue light illumination.Through a series of analysis of crystals morphology,chemical constituents and photoelectric properties,etc.this degradation otherness is imputed to the absorption difference of light with disparate photo wavelengths by perovskite film and the photolysis power of Pb I₂.The perovskite crystalline gradually dissociat under continuous light illumination,and numerous defect appear in the grain crevice,which give rise to the attenuation of devices photoelectric performance.In addition,the vacuum affects the gas permeability of the perovskite surface,separate gaseous decomposition products from perovskite,and expedite the decomposition process of the perovskite film.2.The photo induced performance decay of perovskite solar cells is brought about multiple factors.When the device is in the working state,and the defect state at the perovskite grain boundary triggers the nonradiative recombination of current carriers,resulting in the decrease of charge energy.Perovskite organic cations and anions diffuse and migrate outward,which excited by light illumination energy.The ion migration process not only causes the reversible transformation between the perovskite crystal and the Pb I₂crystal,but also causes the bending of the energy band of the device interface,the obstruction of charge transport and the corrosion of the electrode,which seriously affects the performance of the device.This work provides insights for understanding the synergistic effects of vacuum and light irradiation on perovskite,and has guiding function for subsequent methods to enhance the stability of perovskite solar cells.