As a promising strategy for enhancing light utilization, constructing cell with tandem structure exhibits great potential in achieving high efficiency, which encourages the field of organic solar cells. Here, we develop an advanced interconnecting layer for tandem organic solar cell, which is composed of electron beam evaporated TiO x and PEDOT:PSS. By using electron beam evaporation, a sharp, smooth, and dense TiO x /PEDOT:PSS interface is obtained. By exquisite controlling the O 2 flux during evaporation, efficient electron extraction and low Schottky barrier are obtained in PBDB-TF:GS-ISO/TiO 1.76 and TiO 1.76 /PEDOT:PSS, which guarantee the charge recombination between two subcells. The tandem cell with interconnecting layer of TiO 1.76 /PEDOT:PSS shows 20.27% efficiency, which is certified as 20.0% by National Institute of Metrology, China. Therefore, our result marks the arrival of 20% era in the field of organic solar cells.