A hybrid quantum dot:MXene bulk heterojunction for an efficient infrared self-powered photodetector

Abstract

Lead sulfide (PbS) quantum dots (QDs) have been widely researched for various optoelectronic devices due to their high absorption coefficient and tunable bandgap. In QD thin films, charge carriers are transported via point-to-point hopping that is sensitive to energy disorders, leading to the non-radiative recombination of excitons and carriers. To resolve this problem, we herein introduce a Ti₃C₂T_x MXene:PbS QD bulk heterostructure (BHJ) with the intermediate halogen bridging at the nano-hybrid interface, which boosts the transfer of charges at the donor/acceptor interface and the transport of electrons via 2D continuous MXene nanosheets. Therefore, we proposed a surface halogen (bromide, Br) bridging to replace the carboxyl and hydroxyl groups on the Ti₃C₂T_x MXene, improving its electrical coupling with PbS QDs. The Br-MXene and PbS QD nanobuilding blocks show an enhanced coordinated interconnection with each other, which is preferentially used as the light-sensitive layer for photovoltaic-type self-powered infrared photodetectors (PDs) that can generate a high specific detectivity of 9.2 × 10¹³ Jones and a responsivity of 810 mA W⁻¹ at 808 nm. These efficient self-powered PDs show potential applications in invisible traffic monitoring as well as near-infrared imaging. Our research demonstrates that constructing a strategic BHJ is a promising way to resolve the charge transport bottleneck in colloidal QDs optoelectronic devices.