Study On The Interface Layer For Fully Printable Mesoscopic Perovskite Solar Cells

In recent years,the performance of perovskite solar cells has been improved continuously,and its latest certified efficiency has exceeded 25%.Therefore,perovskite solar cells have become the next generation potential candidates for technology of high-efficiency and low-cost photovoltaics.Fully printable mesoscopic perovskite solar cells（MPSCs）using carbon electrodes have attracted wide attention of researchers due to its simple preparation,low cost,and strong stability.For fully printable MPSCs,titanium dioxide（Ti O₂）is a commonly used material for the electron transport layer（ETL）,but there are defects and trap states in the Ti O₂ ETL,which will trap the injected electrons and cause recombination,which seriously affects the performance of the device.Therefore,manufacturing Ti O₂ ETL with fewer defects and trapped states is critical to improve the performance of fully printable MPSCs.This paper focuses on the research of Ti O₂ compact layer ETL and how to improve the performance of fully printable MPSCs.By introducing a passivation layer and doped materials,high-efficiency fully printable MPSCs can be obtained.This paper mainly includes two research contents,as follows:（1）A thin layer of magnesium oxide（Mg O）was sprayed on the surface of the Ti O₂compact layer to passivate it and used as an ETL for fully printable MPSCs.By optimizing the concentration of the Mg O precursor solution,a maximum power conversion efficiency of 15.11%was achieved,and the hysteresis effect becomes significantly weaker.The effects of the introduction of Mg O on the surface morphology,optical properties,and electrical properties of Ti O₂ compact layers were systematically studied.It was found that Mg O-passivated Ti O₂ films have better flatness and transmittance,higher electrical conductivity,and lower Density of defect states and better charge extraction capabilities.Further research shows that the carrier recombination at the ETL/perovskite interface is suppressed,the charge transfer resistance is reduced,and the device performance is improved.The results show that the use of Mg O to passivate the Ti O₂ compact layer can improve the performance of the fully printable MPSCs,which has a certain reference value for future research.（2）The Ti O₂ compact layer was doped by introducing aluminum（Al）and indium（In）,and the doped Ti O₂ compact layer was used as the ETL for fully printable MPSCs.By optimizing the doping concentration of Al In,the power conversion efficiency of the device was increased to 15.53%,and it has excellent stability and negligible hysteresis effect.Through a series of characterizations,it was found that when the Ti O₂ compact layer is doped,its transmittance and electrical conductivity increase,and its density of defect states decreases.At the same time,the introduction of Al In changes the energy level of Ti O₂,the ETL/perovskite interface has a better energy level arrangement,the improvement of energy level arrangement and the enhancement of electrical properties promote charge extraction and transport,and the charge transfer resistance of the device is reduced,thus the performance of the device is improved.The results show that the use of Al In to dope the Ti O₂ compact layer can improve the performance of the fully printable MPSCs,which has a certain reference value for future research.