Study On Control Of Interface Charge Behavior Of Organic-inorganic Perovskite Solar Cells And Its Influence On Photovoltaic Performance

Perovskite solar cells(PSCs)have been widely researched owing to their high power conversion efficiency(PCE),low cost and large-scale production.In just a few years,PCE has rapidly increased from the initial 3.8%to 25.5%,showing great application potential.Ideal carrier transport layer,high quality perovskite active layer,and good interface(carrier transport layer/perovskite)contact characteristics are the necessary conditions to obtain high efficiency PSCs.The ideal electron transport layer(ETL)should be able to transport electrons,block carrier recombination,and facilitate the growth of perovskite crystal.The high-quality perovskite active layer should have large grain size,low defects and good crystallinity.The good interface contact characteristics of ETL/perovskite layer must satisfy the characteristics of inhibiting interface recombination and improving charge transfer.In this paper,we focus on the photo-electrical properties of ETL,the contact characters of the ETL/perovskite hetero-interface,and quality of the perovskite layer.The affect of above three factors on the photovoltaic performance of the PSCs has been revealed and the related interface charge behavior has also been interpreted.The main contents of research and results in this thesis are as follows:1.To enhance the charge transfer ability of traditional mesoporous titanium dioxide(m-TiO₂)electron transport layer(ETL),hemispherical AgO_x@Ag nanoparticles(HOAPs)were introduced between m-TiO₂and perovskite layer to fill the defect recombination centers in m-TiO₂with the hot carriers generated by HOAPs to improve the charge transfer performance of m-TiO₂and the charge transfer efficiency of m-TiO₂/perovskite interface.The efficiency of the PSCs is promoted significantly from17.87%to 20.33%under the premise of suppressing the charge loss of PCE.2.To solve the problem of mutual restriction between optical gain and electrical loss of device interface,amorphous titanium nitride(a-TiN_x)interface modification layer(IML)was prepared on textured substrate by magnetron sputtering.Using the high light scattering ability of textured substrate to improve the photoelectric characteristics of the PSCs and the light absorption of perovskite;the unique energy level distribution and high electron mobility of a-TiN_xIML contribute to the construction of interface cascade energy levels conducive to photogenerated charge transfer,which can effectively improve the efficiency of interface charge transfer and suppresses ETL/perovskite interface recombination.The results demonstrate that the photovoltaic performance of device can be evidently improved by the combination of textured substrate and a-TiN_xIML(the PCE is 21.64%,and the open circuit voltage(V_oc)is 1.17 V).This study provides a technical and theoretical reference for the development of metal nitride electron transport layer of PSCs.3.In addition to the above charge transfer layer and interface characteristics,the defects of perovskite layer are also the key factors affecting the efficiency of PSCs.Aiming at the deep level defects caused by the dangling bond of lead ion(Pb²⁺),the?-amino-?-Butyrolactone hydrobromide(?-AHBr)is added to the perovskite precursor solution to terminate the perovskite film defects by the-NH₂and-COO^-of the?-AHBr.The crystallization of perovskite thin films was promoted,including achieve uniform,flat and large grains.The charge transport efficiency of perovskite/charge transfer layer interface was improved and the interface recombination was inhibited.The results show that using?-AHBr can significantly improve the photovoltaic performance of the device,and increase the PCE from 18.30%to 20.87%.