Reducing Dark Current Density of PbS Quantum Dot Short-Wave Infrared Photodetectors by Polymer Buffer Layer Modification

Lead sulfide (PbS) quantum dot (QD) photodetectors have received intensive attention due to their great potential in short-wave infrared photodetection. The hole transport layer commonly employed in the PbS QD photodetector consists of passivated PbS QDs with 1,2-ethanedithiol (PbS-EDT). However, EDT causes a severe chemical erosion to the PbS QDs active layer (PbS-AL), which will hinder carrier extraction and increases dark current density. Here, we introduce a PbS QD photodetector modified with a polymer material PTQ10[(thiophene)-alt(6,7-difluoro-2-(2-hexyldecyloxy) quinoxaline)] as a buffer layer at the interface between the PbS-EDT and PbS-AL. The PTQ10 can provide protection for PbS-AL against EDT and facilitating carrier extraction. At a working voltage of −0.5 V, the optimized device with PTQ10 exhibits a low dark current density of 360 nA/cm2, a high detectivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${5}.{4}\times {10}^{{11}}$ </tex-math></inline-formula> Jones at 1080 nm, and a fast response time of 4.90/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.76~\mu $ </tex-math></inline-formula> s.