Control Of Photovoltaic Performance And Stability Of Perovskite Solar Cells Based On Multi-ammonium Macromolecules

Perovskite solar cells(PSCs)based on organic-inorganic hybrid lead halide perovskite materials as the light absorption layers have become a new star in the photovoltaic field,because of their excellent photoelectric properties.The efficiency of PSCs has been continuously improved and the certification efficiency has reached23.7%.However,there is still a big challenge to achieve the large-scale commercial application of PSCs.The poor stability of PSCs has greatly hindered the commercialization of PSCs.The stability issues of PSCs mainly include two aspects:the stability of devices and perovskite materials themselves.In this thesis,a kind of multi-ammonium macromolecule iodides–polyethyleneimine iodides(PEI·HI)have been applied to achieve the interface modification of the NiO_x hole transport layers and the grain boundary modification of perovskite active layers in inverted planar PSCs,respectively.The effect of interface engineering and grain boundary engineering based on multi-ammonium macromolecule iodides on the performance of PSCs is discussed.The main research contents are as follows:Firstly,PEI-HI is employed to modify the surface of NiO_x hole transport layers in inverted planar PSCs.The influences of PEI·HI interface modification on the optical properties and surface morphologies of NiO_x films,crystal growth behaviors of perovsite films,as well as device performance of PSCs,are discussed.Especially,the effects of molecular weight of PEI·HI are studied in details.Finally,efficient and stable PSCs based on high-quality perovskite films are obtained.Upon applying the PEI·HI with molecular weight of 10000,the device shows a power conversion efficiency(PCE)of 19.23%with good repeatability and stabilitySecondly,PEI·HI is used as an additive for perovskite active layer,and the influences of PEI·HI incorporation on the crystal quality,micro-morphologies,opto-physical properties and stability are studied systematically.The results show that PEI·HI can inhibit the formation of grain boundary and greatly improve the stability of perovskite films.Compared with 15.62%PCE of the device without PEI·HI,the PCE can be improved to 17.76%with good stability when the concentration of PEI·HI is 5mg/mL.The study on PEI·HI with different molecular weights shows that the device efficiency is the highest when the molecular weight of PEI is 70000,while the stability is also the best.