Theoretical Study Of Electron For The Hole Transport Layer Of Perovskite Solar Cells

As an essential part of perovskite solar cells,the hole transport layer plays a key role in the transmission of hole carriers.Due to the advantages of adjustable energy level,easy synthesis,easy film formation and high efficiency after the preparation of devices,organic small molecule hole transport materials have become the most widely studied hole transport materials.In this paper,the density functional theory is used to study the properties of three different systems of hole transport materials,which provides a reliable theoretical basis for the development of low cost and high efficiency hole transport layer materials.The research content of this paper is mainly carried out from the following three aspects:(1)Based on diphenylamine for electronic group,fluorene rings as the core group has designed four hole-transporting materials with different replace groups T1-T4,the purpose is to explore diphenylamine donor groups on different substituent effect on the properties of hole-transporting materials,and by studying their electronic,optical and hole-transporting property to get the following conclusion:Compared with the four cavity-transport materials,it was found that the introduction of methoxy group would raise the HOMO level of the cavity-transport materials,while the introduction of methoxy group would lower the HOMO level of the cavity-transport materials.T4 has a lower HOMO level and the highest hole migration rate,so the application of T4 as a hole transport layer in perovskite devices can theoretically make the devices obtain higher open-circuit voltage or short-circuit current and fill factor,so as to improve the PCE of the devices.(2)By reducing the symmetry of the spiral ring,C3 and C4 with high twisted structure were designed based on the cavity transport materials C1 and C2 with high planar structure,and the performance of cavity transport materials with planar structure and high twisted structure was compared by using thick ring as the core.The influence of highly twisted structure on cavity-transport materials was investigated.By studying their electronic,optical and hole transport properties,the following conclusions can be drawn:(3)Based on the second chapter of C4 hole-transporting materials,and designed the condensed nucleus for the center,three aniline for electronic based on the three groups with different replace W1-W3,explore the triphenylamine donor groups on different substituent effect on the properties of hole-transporting materials,and by studying the nature of this several kinds of electronic,optical and hole-transporting get the following conclusion: W3 has a lower HOMO level and the highest hole migration rate,so the application of W3 as a hole transport layer in perovskite devices can theoretically enable the devices to obtain higher open-circuit voltage or short-circuit current and fill factor,thus improving the PCE of the devices.