Field-modulated quantum dot solids enable exceptional gain–bandwidth product of infrared photodetector

Solution-processed shortwave infrared (SWIR) photodetectors are crucial for a wide range of applications, including autonomous systems and quantum technologies. To meet the demands of these applications, achieving both high gain and high bandwidth at 1550 nm—comparable to that of commercial InGaAs photodetectors—is essential. In this study, we present a universal strategy for enhancing gain in photodiode structures via carrier multiplication. We employ solution-processed heterogeneous colloidal quantum dot (CQD) solids to tailor the internal electric field distribution within the device. Notably, by harnessing quantum confinement effects, we demonstrated the localized electric field concentration that facilitates efficient carrier multiplication. The resultant CQD photodetector yields an exceptionally high gain exceeding 3000 at an operating voltage of approximately − 7.6 V, along with a record-high gain–bandwidth product of 72.7 GHz among all previously reported solution-processed infrared photodetectors.