Research On The Novel Organic Solar Cells With Alcohol-soluble Cathode Interfacial Layer

Organic photovoltaic（OPV）technology provides an imperative approach for the effective utilization of clean solar energy,organic solar cells（OSCs）become one of the most vibrant research in the field of OPV due to the potential advantages of light weight,low cost,easy of fabrication and highly tunable properties.Kinds of novel materials,several of cell structures and preparation technics have unremittingly been developed in the past thirty years,and the power conversion efficiency（PCE）of OSCs has already been over 10%.Interfacial materials afford guarantee in improving the PCE of cells and in reducing the cost.In this thesis,certain alcohol-soluble small molecular materials are applied as cathode interfacial modifier to improve the performance of OSCs,and the primary study contents are presented as follows:（1）A derivative of natural chlorophyll,called chlorophyllin（CuCN）,is firstly used as a cathode interfacial layer（CIL）of both fullerene and non-fullerene based OSCs.The results indicate that the performance of PCEs is dramatically improved as the charge-carrier mobility and collection of OSCs is effectively enhanced,with the insertion of CuCN modifier,and the exciton recombination in charge transportation is effectively suppressed,the leakage current of the devices is reduced.As a result,the excellent PCE of 8.35%and 10.55%is achieved for PTB7:PC₇₁BM-based devices and PBDB-T:IT-M-based devices,respectively,which is higher than Ca-modified ones by 12%.Moreover,the raw materials of low-cost chlorophyllin are abundant and the extraction process is rather simple,which makes it a promising cathode modifier of OSCs.（2）The effect of two sulfonate-based small molecular materials（pyrocatechol-3,5-disulfonic acid disodium salt and chromotropic acid disodium salt）in optimizing the properties of OSCs is preliminarily studied.In the experiment,several interlayer modifiers’solution with different concentrations is prepared to explore their impact on photoelectric properties of devices with different interlayer thicknesses;the UV-vis absorption and morphology of active layer(PTB7:PC₇₁BM)with or without the modification or interfacial material are investigated to verdict the function of CILs.The results prove that both two materials play a positive role in improving the properties of OSCs,especially for tiron modified ones,which shows a higher PCE of9.48%for PTB7:PC₇₁BM-based devices.In conclusion,the PCEs of OSCs modified by the alcohol-soluble small material in this thesis are optimized and the preparation costing of devices is reduced,which will promote the commercialization of OSCs.