Organic solar cells are one of the best ways to use solar energy reasonably and efficiently in the future owing to their advantages of low cost, light weight and flexibility etc. The hole transport layer can improve the collection and transport of hole carriers, adjust the energy barrier between the active layer and the electrode, and block electrons to reduce charge recombination, which is a key component of the organic solar cells. The poly(3, 4-ethylene dioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) is widely used organic solar cell hole transport layer materials at present, which has the outstanding advantages of solution processing, high transparency and suitable work function. However, PEDOT: PSS also has some defects, such as low conductivity, strong acid and sensitive to water and air. The modifications of organic solvents, acids, ionic liquids, and salts, which can reduce the interaction between PEDOT and PSS, and promote the phase separation of PEDOT and PSS. Crosslin-king agent was introduce to reduce the water absorption of PEDOT: PSS, the modified layer introducd between PEDOT: PSS and the electrode was to avoid corroding the electrode. In this paper, the modifications of improving conductivity, acidity and sensitivity to water and air for PEDOT: PSS in recent years are reviewed, such as doping, compounding and supplementary modification of post-treatment methodsetc. Although post-treatment methods can overcome a certain defect of PEDOT: PSS, there are great differences among different post-treatment processes, and the process universality is limited. The relationship between modified PEDOT: PSS and battery performance is discussed, and the modification principle of PEDOT: PSS is expounded. We propose to regulate the phase separation of PEDOT and PSS during pretreatment methods improving morphology and uniformity of the PEDOT: PSS film, and can avoid the shortcomings of current post-processing methods, as well as the change of PEDOT chain conformation method to overcome the PEDOT: PSS low electrical conductivity, corrosion, water and air sensitive electrode defects, promoting industrialization of large-area production processes based on PEDOT: PSS organic solar cells. © 2021, Materials Review Magazine. All right reserved.
