Abstract:As a new generation of solid-state film cells, the organic solar cells have become the research focus in the field of renewable energy sources, and the reported power conversion efficiencies are close to 15%. The hole transport material (HTM), a critical component of the organic solar cells, has a major impact on the power conversion efficiency and stability of the organic solar cells. At present, the hole transport materials (HTMs) used in organic solar cells can be divided into two main categories:the inorganic hole transport materials (IHTMs) and the organic hole transport materials (OHTMs). The organic solar cells with IHTMs can achieve satisfing efficiencies, however, these IHTMs are not suitable for the large-scale printing because they need high-temperature vacuum evaporation process. Recently, a large number of OHTMs have been synthesized and used in the organic solar cells successfully. To explore the OHTMs with matched energy levels and higher hole mobility is an effective way to increase the power conversion efficiency and stability of organic solar cells. Therefore, the OHTMs are the present research hotspots of the development of HTMs. Currently, poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) is one of the most commonly used OHTMs. Unfortunately, due to its acidity and hygroscopicity, PEDOT:PSS is unfavorable for the long-term stability of organic solar cells, hindering its long-term manufacturing and application. Meanwhile, OHTMs based on conjugated electrolytes have been evaluated, which can increase the power conversion efficiency of the organic solar cells significantly. In this paper, the effects of molecular structure of conjugated electrolyte-based OHTMs on the power conversion efficiency, fill factor, open-circuit voltage, short-circuit current, and stability are summarized. Furthermore, the energy level, hole mobility, and use of additives are discussed thoroughly. Although some problems still exist in the application of OHTMs, their solution-processing and flexible modification can provide wide space to the development of organic solar cells. The coexistence of challenge and opportunity in this field suggests that with the innovation of OHTMs, the organic solar cells with high power conversion efficiency, high stability, and large-scale manufacturing will emerge in near future, and such organic solar cells posses excellent commercialization prospect.