Advances in Bipolar Photodetectors: Working Principles, Constructions, and Applications

Abstract As a special type of photodetectors, the bipolar photodetectors (BPDs) have attracted extensive attention because of their unique positive and negative bipolar outputs, endowing them attractive applications, such as optical communication, logic gate, and imaging. However, there is still insufficient understanding of the working mechanisms and device structures of BPDs, which limits their optoelectronic performances and practical applications. This review focuses on the working principles, constructions, and applications of BPDs. First, the fundamental working principles of BPDs are analyzed based on device structures, including photoconductors, photodiodes, phototransistors, photoelectrochemical photodetectors, and others. Second, the constructions of BPDs based on different materials (2D materials, organic semiconductors, perovskites, III–V compounds, oxides, and selenides) are reviewed, and their optoelectronic performances are discussed. Third, various applications of BPDs are summarized, including optical communication, logic gate, and imaging. Finally, the challenges and prospects are delivered for developing the state‐of‐the‐art BPDs. It can be expected that this review will provide valuable insights and guidance for future research on BPDs.