Ultrafast and broadband photodetectors based on a perovskite/organic bulk heterojunction for large-dynamic-range imaging

Perovskites peer into near-infrared Novel photodetectors developed by researchers in China provide imaging in the near-infrared (NIR) region with record-breaking efficiency and speed. A new class of semiconducting materials called organic-inorganic hybrid perovskites (OIHPs) display excellent optical and electrical properties for thin-film solar cells, LEDs and light detectors. To expand their detection range to NIR, which is useful for biomedical applications, OIHPs can be combined with structures called organic bulk-heterojunctions (BHJs). Now, Weida Hu, Liang Shen and co-workers at Jilin University, Chinese Academy of Sciences and Peking University have designed new OIHP-BHJ photodetectors that efficiently detect a wide range of both visible and NIR radiation. Their prototype sensors have ultra-fast response times of just 5.6 nanoseconds and remain sensitive even in low brightness, suggesting that they could accelerate the movement of OIHP devices from lab tests to commercial imaging. Organic-inorganic hybrid perovskite (OIHP) photodetectors that simultaneously achieve an ultrafast response and high sensitivity in the near-infrared (NIR) region are prerequisites for expanding current monitoring, imaging, and optical communication capbilities. Herein, we demonstrate photodetectors constructed by OIHP and an organic bulk heterojunction (BHJ) consisting of a low-bandgap nonfullerene and polymer, which achieve broadband response spectra up to 1 mu m with a highest external quantum efficiency of approximately 54% at 850 nm, an ultrafast response speed of 5.6 ns and a linear dynamic range (LDR) of 191 dB. High sensitivity, ultrafast speed and a large LDR are preeminent prerequisites for the practical application of photodetectors. Encouragingly, due to the high-dynamic-range imaging capacity, high-quality visible-NIR actual imaging is achieved by employing the OIHP photodetectors. We believe that state-of-the-art OIHP photodetectors can accelerate the translation of solution-processed photodetector applications from the laboratory to the imaging market.