Amorphous ZnO/PbS quantum dots heterojunction for efficient responsivity broadband photodetectors.

The integration of lead sulfide quantum dots (QDs) with high conductivity material that is compatible with a scalable fabrication is an important route for the applications of QDs based photodetectors. Herein, we firstly developed a broadband photodetector by combining amorphous ZnO and PbS QDs forming a heterojunction structure. The photodetector showed detectivities up to 7.9x1012 jones and 4.1x1011 jones under 640 nm and 1310 nm illumination, respectively. The role of oxygen background pressure on the electronic structure of ZnO films grown by pulsed laser deposition was systematically studied, and it was found to play an important role on the conductivity, associated to the variation of oxygen vacancy concentration. By increasing the oxygen vacancy concentration, the electron mobility of amorphous ZnO layers dramatically increased and work function decreased, which were beneficial for the photocurrent enhancement of ZnO/PbS QDs photodetectors. Our results provide a simple and highly scalable approach to develop broadband photodetectors with high performance.