Study On Mechanism And Application Of Solution-Processable Interfacial Materials In Polymer Solar Cells

In recent years,with the development of non-fullerene acceptor materials,the spectrum utilization range of organic solar cells has been greatly broadened,and the power conversion efficiency of solar cells has been greatly improved,reaching 18.2%at present.However,in organic solar cells,because the Ohmic contact between active and electrode cannot be formed directly,it is necessary to use interface materials to modify the electrode to improve the efficiency of charge extraction and power conversion efficiency.Therefore,the modification of interface materials is an effective way to improve the efficiency of organic solar cells.The modification of the interface is based on the deep understanding of the properties of the interface material,such as the influence of its own defects,the interaction between the interface material and the active layer,such as mechanical contact and electrical contact.Therefore,this paper focuses on the interface modification of organic solar cells to improve the photoelectric conversion efficiency.The main achievements are as follows:1.Three kinds of ZnO materials with different photoluminescence performance were prepared and tested as electron transport layer in different organic solar cell systems.The results show that the residual by-products in the synthesis process of ZnO have a great negative impact on the performance of the device,and the existence of hygroscopic by-products will worsen the contact between ZnO and the active layer,thus affecting the power conversion efficiency of the device.The residual hygroscopic substance can be effectively removed by rinsing with polar solvent after thermal annealed.After the removal of hygroscopic materials,ZnO materials with different fluorescence performance show similar device performance in three representative OPV device systems.More detailed characterization also proves that these intrinsic defects do not bring about different effects on device performance.2.Chloroplatinic acid doped PEDOT:PSS hole transporting layer improves the photoelectric conversion efficiency of organic solar cells.The results show that the active layer will form a tight molecular lock at the interface through the carbonyl group on the polymer donor and platinum ion coordination in the process of thermal annealing,and make the polymer donors close to the anode interface layer to form a more orderly molecular stacking.After doped,the carrier lifetime is increased from 60μs to 165μs.The carrier extraction probability increases from 81.5%to 88.4%at the maximum power point,and the device efficiency increases from 15.7%to 16.5%.3.Using bis（catecholato）diboron（B₂Cat₂）to dope molybdenum oxide hydrogen peroxide solution,using the coordination of boron and bridge oxygen and the alcohol solubility of B₂Cat₂,the alcohol soluble molybdenum oxide（S-MoO_X）was prepared and applied to inverted solar cells.High short circuit current density nearly 26mAcm^-2 was obtained without post-treatment and the power conversion efficiency of 15.2% are realized,which is one of the highest efficiency of solution processed molybdenum oxide.Result show that the S-MoO_X has a broad band gap of 4.13eV and high work function of 5.54eV.The quantum efficiency of S-MoO_X based device is obviously improved in the range of 300～500 nm than its thermal evaporated counterpart（E-MoO_X）.The decreased intensity of the reflection spectrum in S-MoO_X based device suggests that more incident light is captured in OPV device.In addition,the photoluminescence quenching test of donor materials proves that the S-MoO_X has more advantages in charge extraction.