Research On Transport Properties Of Perylene Diimide Dimer Derivatives In Photovoltaic Devices

Up to now,perovskite solar cells?PerSCs?and organic solar cells?OPV?are considered to be the two most promising areas of photovoltaics.The n-type material which plays a role in charge transfer has a direct influence on the photovoltaic performance of the device.Efficient electron transport materials require properties such as high electrical conductivity,high electron mobility,and good film formation.Perylene diimide derivatives,as typical electronic transport materials,have the advantages of simple synthesis,low price,adjustable energy levels and stable properties.Therefore,a more representative perylene diimide dimer derivative?Bis-PDI-T-EG?was selected as the research object in this paper.However,compared with traditional fullerene materials,its charge transfer ability still needs to be improved.Firstly,as the electron transport layer?ETL?of PerSCs,the effects of four different solvent additives and graphene doping on the electron transport properties of Bis-PDI-T-EG were studied.It was found that 1,8-diiodooctane?DIO?had little effect on the morphology of the films,but the film particles doped with1-chloronaphthalene?CN?,1-phenylnaphthalene?PN?and 1-methylnaphthalene?MN?were significantly reduced.Then,PerSCs devices were prepared by doping Bis-PDI-T-EG with DIO,CN,PN and MN,respectively.The results show that the performance of the device doped with additives is improved,especially by using MN as a solvent additive for Bis-PDI-T-EG.This is attributed to the excellent solubility of MN to Bis-PDI-T-EG,which can easily form a high quality film on the perovskite layer,and the film conductivity is improved.Based on the addition of MN,the conductivity of the film was further improved by graphene doping Bis-PDI-T-EG.The planar inverted perovskite solar cell achieved a power conversion efficiency?PCE?of 15.11%,and the hysteresis was significantly weakened compared to the undoped device.The current was stable at 20.91mA·cm^-2 for 100 s.Hence,doping MN and graphene is a highly efficient method for improving the electron transport properties of perylene diimide dimer derivatives.On the other hand,using Bis-PDI-T-EG as the acceptor material of polymer solar cells?PSC?in OPV,the effect of different polymer donors on the electron transport properties of Bis-PDI-T-EG in PSC was studied.In this paper,two typical electron donors,PBDTTT-EFT?PCE10?and PBDB-T?PCE12?,were combined with Bis-PDI-T-EG to make PSC.The study found that the combination of PCE10 has better quality film,high electron mobility and achieves superior device performance than PCE12.Therefore,high electron mobility is a key factor leading to efficient charge transfer and extraction.The difference in membrane morphology of the blend determines the difference in electron mobility.Consequently,the Bis-PDI-T-EG based blend membrane can achieve higher electron transport performance only if it has favorable phase separation morphology.