Diketopyrrolopyrrole semiconductor/carbon quantum dots based planar heterojunctions for high-performance organic phototransistors
In this work,planar-heterojunction organic phototransistors(OPT)have been constructed from solu-tion process,by combining a semiconducting diketopyrrolopyrrole polymer PDVT-10 and a novel carbon nano-material-carbon quantum dots(CQDs).The PDVT-10/CQDs planar heterojunction films,possessing the opti-cal properties of both PDVT-10 and CQDs,reveal strong optical absorption in a wide spectral region from ultra-violet to near infra-red.Compared with pristine PDVT-10 phototransistors,such planar-heterojunction OPTs exhibit a remarkably higher performance on broad-spectrum photo-detection,with a photoresponsivity of 2.6 × 104 A/W,a specific detectivity of 2.4× 1013 Jones,and maximum light sensitivity higher than 104 under the 450-nm laser irradiation,as well as with a responsivity of 4.4×104 A/W and a specific detectivity of 1.2×1013 Jones under the 808-nm laser irradiation.Based on the study of the photo-response mechanism for these devices,the performance improvement of the PDVT-10/CQDs based OPTs should be attributed to the favorable energy level alignment at the PDVT-10/CQDs interfaces,which enhances interfacial exciton dissociation and charge separa-tion,meanwhile effectively suppresses the hole-electron recombination in the light-absorption layer.Further-more,the formation of efficient carrier conduction pathway is benefited from high hole-mobility of PDVT-10 for the OPT performance enhancement.Our work offers a valuable avenue for the development of high performance light detectors.
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