Improving the Performance of InAs Colloidal Quantum Dot Photodetectors Through Zinc Doping

NIR photodetection is the key technology for emerging applications such as bioimaging, autonomous driving, and augmented reality. Owing to their tunable bandgap, solution processibility, and non-toxic components, InAs colloidal quantum dots (CQDs) are attractive materials for the NIR photodetector. Recently, there have been attempts to employ InAs CQDs solids as active layers in p-n junction photodiodes. [1] For these devices to achieve high performance, control over carrier type, concentration, and removal of traps are fundamental but it remains a challenge since InAs CQDs are generally reported to exhibit n-type with high trap density. [2] Here, we incorporated environmentally benign Zn on InAs CQDs via post-synthesis doping process. Through this treatment, we were able to switch the n-type property of original InAs CQDs into p-type with a controlled doping level, demonstrated by field-effect transistors, and inductively coupled plasma mass spectroscopy. Then, using the Zn doped InAs CQD solids capped with short ligands, we fabricated InAs CQD photodiode including n-type metal oxide for the electron transport layer. To study the impact of doping, the device with n-type InAs CQD was also implemented. Finally, device performance was compared evaluating the current-voltage curve, external quantum efficiency, and detectivity. We believe that this study introduced an effective strategy for improving the performance of nanocrystal-based optoelectronic devices and laid the groundwork for their commercialization.<br/>[1] Nano Lett. 2021, 21, 14, 6057–6063<br/>[2] Nat comm 9, 4267 (2018)