Cesium carbonate can be used as a modified layer between the active layer of the solar cell and the Al electrode to improve the conversion efficiency of the device, generate Al-O-Cs compounds, reduce the series resistance of the battery, and improve the short-circuit current and photoelectric conversion efficiency of the solar cell, and Due to the compactness of the cesium carbonate layer itself, the stability of the device has also been significantly improved. The strong metallic n-type heavy doping effect of cesium in cesium carbonate, the Al/CsCO cathode modified with cesium carbonate nano-interface can greatly increase the injection of electrons, and significantly improve the performance of the inverted top-emitting structure OLED device. Cesium carbonate is also used as a catalyst for the synthesis of alkyl aryl ethers.