Research On Modification Of Electron Transport Layer And Perovskite Layer In Carbon Electrode Perovskite Solar Cells

As we all know,fossil energy has played an enormously significant role in the development of people.As fossil fuel dwindles and its pollution to the environment intensifies,people are gradually embracing the concept of the new energy sources that are friendly to environment.As a recyclable,large inventory clean energy,solar power can satisfy the demand for green,eco-friendly energy of humans.Among them,perovskite solar cells,both organic and inorganic hybrid,boast remarkable properties,including eco-friendly,low cost,simple preparation conditions,and a photoelectric conversion efficiency that rivals silicon-based solar cells.Perovskite solar cells prepared by traditional methods are prone to produce various defects at the interface of each layer as well as within the perovskite active layer.Especially in the carbon electrode perovskite cell devices without hole transport layer,interface problems between layers,combined with its internal flaws,will have a major effect on its photoelectric performance and steadiness.The commercial development of efficient and inexpensive perovskite solar cells still faces great challenges.To solve these problems,the conversion of carbon electrode perovskite cells without hole transport layer was studied in this thesis,including the following three aspects.（1）Based on the excellent physical,chemical and photoelectric properties of rare earth metals,we choose to introduce Eu³⁺between the electron transport layer and the perovskite layer.The electrical conductivity and ultraviolet absorption tests show that Eu³⁺applied to perovskite solar cells can improve the electrical conductivity of SnO₂electron transport layer and the absorption ability of the perovskite active layer was enhenced.The XRD,PL,SEM and other analysis indicate that the addition of Eu³⁺improved the optoelectronic performance of the film,enhanced the crystallinity and light absorption capacity of perovskite,weakened the non-radiation recombination of charge,ultimately obtaining a photoelectric conversion efficiency of 13.40%.（2）The MAPbI₃solar cells prepared at low temperature with SnO₂as the electron transport layer often form oxygen vacancies and other defects on the surface of SnO₂,which will cause the the interface between the electron transport layer and perovskite to produce non-radiative charge recombination,leading to a decrease of electron mobility and thus reducing the performance of perovskite devices.In this experiment,the problems of oxygen vacancy defect and interfacial contact were solved by mixing L-proline containing bifunctional groups into SnO₂electron transport layer.A bridge between the electron transport layer and the perovskite layer is formed by the bifunctional carboxyl and amino group of L-proline,thus eliminating the flaws of the interface between them.The characterization of EIS and PL proved that the interface charge recombination of perovskite devices was optimized.Based on the inclusion of SnO₂electron transport layer with L-proline,the efficiency was 14.49%with good reproducibility.（3）Although the performance of perovskite solar cells can be improved by modifying the electron transport layer and interface,the internal problems of perovskite active layer are still a hindrance to its development,because the internal defects of perovskite cell devices prepared by solution method are inevitable.In order to solve the defects in perovskite,n-tert-butylacrylamide（TBA）was added into perovskite as an additive material.The C=O and N-H contained in TBA can act as Lewis acid base to coordinate with the free Pb²⁺in perovskite and thus passivate the Pb²⁺defects.At the same time,the large tert-butyl group can avoid the unnecessary polymerization of some groups.Through SEM,UV,PL,TRPL and other characterization,it can be seen that the addition of TBA makes the morphology of perovskite film become good,promotes the crystallization of perovskite,accelerates the transfer rate of carrier,and finally the device based on TBA obtains the efficiency of 15.11%.