Acid-base Stability And Large-area Coating Of Active Layer Of Organic Solar Cells

Organic solar cells have the advantages of excellent mechanical flexibility,printability and coating,etc.,which are the research hotspots in recent years.The photoactive layer is the core part of the organic solar cells,its chemical properties and film-forming behavior will directly affect the efficiency and stability of the organic solar cells.This paper takes the non-fullerene photoactive layer as the research object,and studies the chemical stability of the non-fullerene active layer in the acidic and alkaline environment that are often introduced in the coating process.And then,for the problem of uneven film distribution that the active layer film commonly meets in knife coating,a solution to dilute the solution for multiple blade-coating is proposed.The main results are as follows:Firstly,the chemical stability of the non-fullerene active layer under different acidity and alkalinity was studied,and it was found that the non-fullerene active layer would lose its original photoelectric properties in an alkaline environment,while it was stable in an acidic environment.The characterization revealed that the active layer material is prone to undergo an addition reaction with alkali,which destroys the original chemical structure and electronic structure in the material.It is further discovered that adding acid to the system can reverse this addition reaction and regain the original photoelectric properties.This discovery provides guidance for the design of the interface layer and the all-solution printing of organic solar cells;Secondly,a new film coating method is proposed,which adopts the method of diluting the solution and multiple blade coatings to obtain a uniform film than a single blade coating.In the process of increasing the frequency of blade coatings from one to four,the average efficiency of the standard device with an effective area of 0.04 cm~2 is increased to 14.0%,which is equivalent to the 14.3%efficiency of the spin-coated reference device,and the efficiency standard deviation of the device has also been greatly decreased;Finally,a single-cell large-area organic solar cell with an area of 10.0 cm~2 was prepared based on the method of multiple blade coatings,with an efficiency of 7.3%;and an 8-cells organic solar module with an area of 10.0 cm~2 was prepared at the same time,achieving the efficiency of 12.0%;The large-area organic solar cell prepared by this method has also a greatly improved yield compared with the organic solar cell obtained by a single blade coating.