Ultrasensitive Solution-Processed Broadband PbSe Photodetectors through Photomultiplication Effect.

Broadband photodetectors have important applications in both scientific and industrial sectors. In this study, we report room-temperature-operated solution-processed photodetectors by PbSe quantum dots (QDs) with spectral response from 350 to 2500 nm. In order to boost both external quantum efficiency (EQE) and projected detectivity ( D*), the hole-trap-assisted photomultiplication effect through the EDT-PbSe QD/TABI PbSe QD double-thin-layer thin film, where EDT-PbSe QDs are 1,2-ethanedithiol (EDT)-capped PbSe QDs and TABI-PbSe QDs are tetrabutylammonium (TABI)-capped PbSe QDs, is applied. To further enhance D*, a thin layer of the conjugated polyelectrolyte, which offers significant hole injection resistance for suppressing dark current but enhancing photocurrent under illumination due to the photoinduced self-doping process, is applied for reengineering the electron extraction layer in PbSe QD-based photodetectors. As a result, at room temperature, PbSe QD-based photodetectors exhibit over 450% EQE and over ∼1012 Jones D* in the visible region and over 120% EQE and D* ∼4 × 1011 Jones in the infrared region. These results demonstrate that our studies provide a simple approach to realize room-temperature-operated solution-processed broadband photodetectors.