Passivation Of SrCl₂ On Perovskite Films Adjusted With MACl For Highly Efficient And Stable Organic-inorganic Perovskite Solar Cells

Organic-inorganic perovskite solar cells?PSCs?have attracted exceptional attention over the past few years due to its outstanding light absorption,high carrier mobility,long diffusion length,flexible band-gap adjustment and superior ambipolar transport.With a series of research applications such as doping engineering,solvent engineering,and interface engineering,the photoelectric conversion efficiency?PCE?of PSCs have exceeded 25%by now since the first report in 2008.Thus,PSCs have been expected to be a powerful competitor for silicon-based solar cells soon in the photovoltaic market.Moreover,perovskites have been widely applied in LEDs,transistors,and photodetectors.However,perovskites could be affected by light,moisture,temperature,and ion migration,which might accelerate the decomposition of perovskite devices and limit the commercialization.Although simple encapsulation can rule out the negative influence of moisture and oxygen,it cannot mitigate the deterioration caused by other intrinsic factors.In this dissertation,strontium chloride?Sr Cl₂?passivation on methylamine chloride?MACl?adjusted perovskite films for highly efficient and stable organic-inorganic PSCs is systematically demonstrated.On the basis of controlling the grain size of perovskite with MACl,Sr Cl₂ was doped to passivate the internal defects of perovskite films.Due to the advantage of similar radius of Sr²⁺and Pb²⁺ions,Sr Cl₂ promoted the transition of perovskite from delta to alpha phase in the annealing process due to defect passivation.Perovskites doped with a certain proportion of Sr Cl₂ showed superior charge-transport and improved PCE in devices.Besides,we have ameliorated the stringent ambient preparation technology and produced highly efficient devices in the air by adjusting rotate speed and perovskite compositions systematically.Beyond the control of perovsktie films with MACl,we covered the Sr Cl ₂ layer on FA-based perovskite by one-step spin-coating method and elucidated the microstructure,carrier diffusion length and PCE under 40?55%humidity.It was found that the Sr Cl₂-locking layer prevented ion migration of cations and inhibited non-radiative recombination of carriers efficiently.The PCE of PSCs has risen from the original 18.80%to current 21.11%and showed over 90%retention of the initial value during the test of 1000 h storage in the dry air.Passivation of inorganic small molecules on perovskite films significantly improved the stability and PCE of PSCs.This approach avoided the environmental requirement of glove box system and might accelerate the practicality and commercialization of devices,providing new insight into research in this area.