Performance optimization in PbS quantum dot based infrared thin-film photodetectors

Because of its applications in areas ranging (e.g. remote sensing, cameras), imaging in the infrared (IR) range has garnered considerable attention. Photons in the short wave infrared (SWIR) range are less scattered by the particles in the atmosphere. As a result, SWIR light has strong penetrating qualities, allowing for sharp imaging even under poor weather conditions. Silicon, on the other hand, as significant in electronics, is commonly deployed in the industry for detection and imaging. However, because silicon's absorption capacity decreases dramatically beyond 1100 nm, imaging at SWIR requires alternate materials to be integrated atop silicon. Because of its size and tunable bandgap, solution-processable quantum dot (QD) photodetectors provide SWIR sensitivity. They are compatible with silicon substrates. They may be connected to silicon substrates utilizing low-cost and diverse technologies such as spin coating. However, in order to achieve good performance, QD photodetectors must have low dark current and high external quantum efficiency. To that aim, charge transport layers should be tuned properly since they play an important role in suppressing dark current. In this thesis performance optimization was done by employing different hole transport layers and electron transport layers into the lead sulfide (PbS) quantum dot based photodetectors. Various characterization methods (e.g., external quantum efficiencyvoltage/ wavelength, current-voltage, absorbance measurements) were used to characterize fabricated devices that include novel transport layers. Followingly, best performing materials as transport layers were used in the structure of the photodetector which is on a silicon substrate that mimics CMOS ROIC structure. As a final step, studies were carried out to thin the absorber layer in order to reduce the cost of the product and make the production process easier.