Application of Buffer Layer to Improve the Efficiency of Organic Solar Cells

Organic solar cells (OSCs) are widely studied for their advantages such as simple production, low cost, good flexibility, and large‐area printing. The buffer layer between electrodes and the photoactive layer has a significant impact on the efficiency and stability of OSCs. In order to lower the energy barrier height at the interface, provide an Ohmic contact with lower series resistance, and increase the charge collection efficiency of the corresponding electrodes for either holes or electrons, suitable electrode buffer materials can be chosen. The selection of electrode buffer layer has an important effect on the photoelectric conversion efficiency. Therefore, the study of buffer layer characteristics has certain guiding significance for the improvement of device structure and performance optimization. At present, the buffer layer materials used in OSCs are mainly organic polymer materials, organic small molecule materials, metal fluoride, metal oxides, and so on. Herein, the structure and working principle of OSCs are introduced first. Then, the properties and function of buffer layer in OSCs are summarized and discussed. Finally, the application of common buffer layer materials in OSCs is summarized, and how to improve the performance of the device is described.